[Radio Sets Scr-399-a and Scr-499-A]
[From the U.S. Government Publishing Office, www.gpo.gov]
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WAR DEPARTMENT TECHNICAL MANUAL
NON-CIRCUUTING
RADIO SETS
SCR-399 -A AND
SCR-499-A
WARNING: This manual is the property of the United States Government, and is printed and distributed solely for the use of the •military, naval, and civilian personnel of the War and Navy Departments, and may not be published or reproduced in whole or in part, or in any manner or form (except by lawful copyright holders who may reproduce their copyrighted material in its original form) unless specifically approved by authorized military public relations agencies.
1EAR DEPARTMENT ■ MARCH 1945
WAR DEPARTMENT TECHNICAL MANUAL
TM 11-281
THIS MANUAL SUPERSEDES TM 11-281, 4 SEPTEMBER 1943; TB 11-281-1, 13 OCTOBER 1944, AND TB 11-281-2, 25 NOVEMBER 1944.
RADIO SETS
S C R - 3 9 9 - A A N D
S C R - 4 9 9 - A
WAR DEPARTMENT • MARCH 1 <) 4 5
WARNING: This manual is the property of the United States Government, and is printed and distributed solely for the use of the military, naval, and civilian personnel of the War and Navy Departments, and may not be published or reproduced in whole or in part, or in any manner or form (except by lawful copyright holders who may reproduce their copyrighted material in its original form) unless specifically approved by authorized military public relations agencies.
United States Government Printing Office
Washington: 1945
WAR DEPARTMENT Washington 25, D. C., 31 March 1945
TM 11-281, Radio Sets SCR-399-A and SCR-499-A, is published for the information and guidance of all concerned.
[AG 300.7 (8 Jan 45)]
By order of the Secretary of War :
Official :
J. A. TJLIO
Major General
The Adjutant General
G. 0. MARSHALL
Chief of Staff
Distribution :
AAF (5) ; AGF (5) ; ASF (2) ; T of Opn (5) ; Dept (5) ; Def Comd (2) ; Base Comd (5) ; AAF Comd (2) ; Arm & Sv Bd (2) ; S Div ASF (1) ; Tech Sv (2) ; SvC (5) ; Area ASvC (2) ; WDGS Lib (5) ; PC&S (2) ; PE (2) ; Dep 11 (2) ; Gen Oversea SOS Dep (Sig Sec) (2) ; GH (2) ; M Cone C (2) ; Air Base Hosp (2) ; Gen Sv Sch (5) ; Sp Sv Sch (10) ; USMA (10) ; ROTC (5) ; Lab 11 (2) ; Sig AS (2) ; Rep Shop 11 (2) ; A (5) ; D (2) ; AF (2) ; Two (2) copies to each of the following: T/O & E 1-12; 1-27; 1-37; 1-47; 1-117; 1-127; 1-137; 1-147; 1-157S; 1-167; 1-252; 1-257; 1-267; 1-312; 1-317; 1-452T; 1-460-1S; 1-469S; 1-487; 1-487S; 1-547; 1-637; 1-637S; 1-757; 1-758; 1-759; 1-767; 1-768; 1-777S; 1-779; 1-1027; 30-47; Five (5) copies to each of the following: T/O & E 2-2; 2-22; 4-232; 4-240-1S; 5-512S; 11-7; 11-7S; 11-15; 11-18; 11-47; 11-57; 11-97; 11-107; 11-127; 11-147S; 11-157T; 11-217; 11-237; 11-247; 11-257; 11-287; 11-317; 11-338; 11-460-1S; 11-477S; 11-517; 11-537S; 11-557; 11-557T; 11-587; 11-592; 11-597; 44-7; 44-147S.
Refer to FM 21-6 for explanation of distribution formula.
ii
CONTENTS
i
CHAPTER I. GENERAL
Section I. Description. Paragraph Page
General............................................................................ 1 3
Radio Set SCR-399-A...................................................................... 2 4
Radio Set SCR-499-A...................................................................... 3 5
Technical characteristics ............................................................... 4 6
List of components and packaging data.................................................... 5 9
Major components ........................................................................ 6 12
Radio Transmitter BC-610-E............................................................... 7 14
Speech Amplifier BC-614-E................................................................ 8 14
Junction Box JB-70—A..................................................................... 9 15
Radio Receivers BC-342-( ) and BC-312-( )................................................ 10 15
Antenna Tuning Unit BC-939-A....................................................... 11 15
Antenna system .......................................................................... 12 15
Power Unit PE-95-( )..................................................................... 13 16
Other components ........................................................................ 14 17
Chest CH-120-A (main operating).......................................................... 15 17
Chest CH-121-A .......................................................................... 16 17
Chest CH-89-A ......................r.............................................. 17 17
Chest CH-119-A .......................................................................... 18 18
Chest CH-88-A ...........................................................:......... 19 18
Frequency Meter Set SCR-211-( ).......................................................... 20 18
Rectifier RA-63-(*) ..................................................................... 21 19
Cordage ................................................................................. 22 20
Remote control equipment................................................................. 23 23
Batteries ............................................................................... 24 23
Crystals ................................................................................ 25 24
II. Installation.
Siting .................................................................................. 26 25
Uncrating, unpacking, and checking Radio Set SCR-399-A................................... 27 25
Uncrating, unpacking, and checking Radio Set SCR-499-A................................... 28 26
Installation of Radio Set SCR-399-A...................................................... 29 29
Installation of Radio Set SCR-499-A...................................................... 30 31
Connections and interconnections of Radio Set SCR-399-A.................................. 31 32
Connections and interconnections of Radio Set SCR-499-A.................................. 32 32
Installation of antennas on Radio Set SCR-399-A.......................................... 33 33
Installation of antennas on Radio Set SCR-499-A.......................................... 34 34
Installation of dry batteries............................................................ 35 34
Placing storage batteries in service..................................................... 36 34
Repacking ............................................................................... 37 34
CHAPTER 2. OPERATING INSTRUCTIONS.
Section I. Controls and their use.
General.................................................................................. 38 37
Transmitter controls..................................................................... 39 37
Tuning unit controls..................................................................... 40 40
Antenna tuning unit controls............................................................. 41 40
Junction Box JB-70-A controls............................................................ 42 41
Speech Amplifier BC-614-E controls....................................................... 43 42
Junction Box JB-60-A controls............................................................ 44 43
Rectifier RA-63-( ) controls............................................................. 45 43
II. Tuning. Preliminary steps ......................................................................... 46 44
Tuning Radio Transmitter EC-610-E for c-w operation [master-oscillator control] ... 47 46
Tuning Radio Transmitter BC—610-E for c-w operation [crystal-control]............... 48 51
Tuning Radio Transmitter BC-610—E for voice operation................................ 49 53
iii
III. Normal operation. Paragraph Page
C-w operation........................................................................ 50 55
Voice operation...................................................................... 51 55
Changing type of emission............................................................ 52 58
Changing frequency .................................................................. 53 58
Presetting tuning units.............................................................. 54 59
Additional operating instructions.................................................... 55 59
IV. Remote control operation. Connection of remote stations............................................................. 56 60
Remote voice operation............................................................... 57 61
Remote c-w operation................................................................. 58 61
Remote receiver operation............................................................ 59 61
V. Power source operation. Operation from commercial power source................................................... 60 62
Operation of trailer 100 feet from truck............................................. 61 62
Operation of trailer 200 feet fyom truck............................................. 62 62
Use of Power Unit PE-95-( ) to supply power to auxiliary equipment................... 63 62
Operation of low-voltage power supply system......................................... 64 63
VI. Equipment performance check list. Purpose and use............................................................................ 65 63
Check list.......................................................................... 66 64
CHAPTER 3. PREVENTIVE MAINTENANCE.
Section I. Preventive maintenance techniques. Meaning of preventive maintenance................................................................ 67 71
Description of maintenance techniques................................................ 68 71
Recommended lubricants .............................................................. 69 72
Vacuum tubes......................................................................... 70 72
Capacitors ......................................................................... 71 73
Resistors ........................................................................... 72 73
Fuses . ............................................................................. 73 73
Bushings and insulators.............................................................. 74 74
Relays......................< m. ................................................ 75 74
Switches ............................................................................ 76 74
Coils ............................................................................... 77 75
Rheostats and potentiometers......................................................... 78 75
Terminal blocks ..................................................................... 79 75
Multiple connectors ................................................................. 80 75
Cords and cables..................................................................... 81 76
Meters ............................................................................. 82 76
Pilot lamps ......................................................................... 83 76
Jacks................................................................................ 84 76
Dynamotors and motors................................................................ 85 76
Cabinets, chassis, and mountings..................................................... 86 77
Headsets, microphones, keys, and loudspeakers........................................ 87 77
Couplings and control shafts......................................................... 88 77
Gears .'............................................................................. 89 77
Antennas ............................................................................ 90 77
Reels .................’.......................................................... 91 78
II. Itemized preventive maintenance. General................................................................................. 92 78
Common materials needed.......................................................... 93 78
Item 1. Exterior of Radio Sets SCR-399-A and SCR-499-A........................... 94 78
Item 2. Headsets, microphones, keys, and loudspeakers.............................. 95 79
Item 3. Cords, cables, and connectors.............................................. 96 79
Item 4. Antennas .................................................................. 97 79
Item 5. Accessories .....................-........................................ 98 79
Item 6. Interior of Radio Sets SCR-399-A and SCR-499-A............................. 99 79
Item 7. Radio Transmitter BC-610-E................................................. 100 79
Item 8. Antenna Tuning Unit BC-939-A............................................... 101 79
Item 9. Speech Amplifier BC-614-E.................................................. 102 79
Item 10. Junction Box JB-70-A....................................................... 103 79
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Paragraph Page
Item 11. Rectifier RA-63-(*) .............................................. •........ 104 80
Item 12. Heating and ventilating system............................................... 105 80
Item 13. Auxiliary batteries ......................................................... 106 80
Preventive maintenance check list..................................................... 107 80
III. Lubrication.
IV. Special tools. Relay and commutator tools................................................................. 108 80
Construction of special relay and commutator tools.................................... 109 81
Safety shotting stick and jumper wires.............................................. 110 81
V. Moistureproofing and fungiproofing. General................................................................................... Ill 81
Treatment ............................................................................ 112 82
Step-by-step instructions for treating Radio Transmitter BC-610-E.................... 113 82
Step-by-step instructions for treating Speech Amplifiei1 BC-614-E.................... 114 85
Step-by-step instructions for treating Junction Box JB-70-A.......................... 115 86
Instructions for treating Radio Receivers BC—312—( ) and BC-342-( ).................. 116 87
CHAPTER 4. AUXILIARY EQUIPMENT.
Section I. Frequency Conversion Kit MC-509.
Description .......................................................................... 117 91
Installation on Antenna Tuning Unit BC-939-A........................................... 118 91
Erection and installation of antenna mast.............................................. 119 92
Modification of Radio Transmitter BC-610-E....................................-........ 120 93
Operation of Radio Sets SCR-399-A and SCR-499-A in frequency range of 1.0 to 2.0 me................................................................................ 121 93
Theory of equipment.................................................................... 122 94
II. Doublet antenna. Purpose ................................................................................... 123 95
Description ........................................................................... 124 95
Location and erection of mast........................................................ 125 95
Installation in Radio Transmitter BC-610-E............................................. 126 99
Maintenance .......................................................................... 127 101
Differences in coil units.............................................................. 128 102
Theory of equipment.................................................................... 129 102
CHAPTER 5. REPAIR INSTRUCTIONS.
Section I. Simplified block diagrams.
Radio Transmitter BC-610-E, c-w operation.............................................. 130 105
Speech Amplifier BC-614-E............................................................ 131 106
Radio Transmitter BC-610-E and Speech Amplifier BC-614-E [phone operation] .... 132 106
II. Theory of Radio Transmitter BC-610-E.
Oscillator stage ...................................................................... 133 106
Crystal control of master oscillator................................................... 134 109
Buffer-doubler stage .................................................................. 135 110
Intermediate power-amplifier stage..................................................... 136 111
Power-amplifier stage.................................................................. 137 111
Antenna tuning unit.................................................................... 138 112
Modulator section ....',.............................................................. 139 114
Power supplies ........................................................................ 140 115
Switches .............................................................................. 141 117
Relays................................................................................. 142 121
Controls and meters.................................................................... 143 122
III . Theory of Speech Amplifier BC-614-E.
First a-f amplifier.................................................................... 144 123
Second a-f amplifier................................................................... 145 123
Third a-f amplifier and phase inverter................................................. 146 124
Fourth a-f amplifier................................................................... 147 126
Modulation limiter..................................................................... 148 126
C-w sidetone.......................................................................... 149 127
Power supply .......................................................................... 150 128
Jacks, controls, and meters .......................................................... 151 128
v
Paragraph Page
IV . Theory of Junction Box JB-70-A. Transmitter control switch SW203...................................................... 1^2 129
REMOTE CONTROL EE-8 switch SWJ02................................................. 453 130
Relay RY:w ...................................................................... 154 131
Receiver disabling switches SW200 and SW201..................................... 155
Receiver output switch SW204..................................................... 156 133
C.W. SIDETONE switch SW!ro....................................................... 157 133
START-STOP switch SW208.......................................................... 158 I33
Battery source switch SW207...................................................... 159 134
Circuit breaker CB200............................................................ 159 134
Surge filters ................................................................... 151 I34
V. Over-all system function. General............................................................................... 152 135
C-w operation .................................................................. 163
Phone operation.................................................................. 154 HO
Remote operation................................................................. 165 140
Rectifier RA-63-(*) ............................................................. 166 140
VI. Changes in equipment. Changes in Radio Transmitter BC-610-E.................................................. 167 142
Changes in Speech Amplifier BC-614-E............................................. 168 143
Wiring change in Junction Box JB-70-A............................................ 169 143
Change in coupling coils for doublet antenna kit................................. 170 144
VII. Trouble shooting. General trouble-shooting information................................................... 171 144
Voltage measurements ............................................................ 472 145
Resistance measurements.......................................................... I?3 146
Capacitor tests ................................................................. 474 147
Current measurements ............................................................ 175 147
Tube checking.................................................................... 176 148
Analyzer BC-1052-E........................................................... 177 148
Trouble-shooting procedures ................................................... 178 149
Trouble-shooting charts ................................................’........ 179 149
Sectionalizing trouble in Radio Sets SCR-399-A and SCR-499-A..................... 180 151
Localizing trouble in Radio Transmitter BC-610-E................................. 181 152
Localizing trouble in Junction Box JB-70-A....................................... 182 153
Localizing trouble in Speech Amplifier BC-614-E.................................. 183 154
VII I. Repairs. Replacement of parts.................................................................... 184 154
Replacement of tubes............................................................. 185 154
Removal of Antenna Tuning Unit BC-939-A. . . . .................................. 186 155
Removal of top of transmitter cabinet............................................ 187 155
Removal of r-f section........................................................... 188 155
Removal of chests from shelter................................................... 189 155
Removal of Radio Transmitter BC-610-E............................................ 190 156
Replacement of switches in Radio Transmitter BC-610-E........................... 191 156
Replacement of parts in Speech Amplifier BC-614-E................................ 192 156
Removal of Junction Box JB-70-A.................................................. 193 156
Rustproofing and repainting...................................................... 194 156
War Department Unsatisfactory Equipment Report................................... 195 157
IX . Alignment and adjustment. Neutralization........................................................................ 196 157
Modulation limiter............................................................... 197 157
APPENDIX I. MAINTENANCE PARTS LIST.................................................................... 182
II. REFERENCES ...................,.......................................................... 183
vi
LIST OF TABLES
Table Page
Chests and contents................................................................................ I 25
Typical packing list for Radio Set SCR-499-A..................................................... II 28
Tuning components ................................................................................ HI 51
Tuning ranges for long wire antennas when used with Antenna Tuning Unit BC-939-A.................. IV 51
Crystals and operating frequencies................................................................. V 52
Approximate dial settings using Antenna Tuning Unit BC-939-A............................ VI 93
List of components in doublet antenna kit........................................................ VII 96
Continuity checks for cables and terminal strips................................................ VIII 186
Data for checking trans^orpiers, chokes, and inductors............................................ IX 192
Performance characteristics ....................................................................... X 194
Characteristics of vacuurh tubes.................................................................. XI 194
vii
DESTRUCTION NOTICE
WHY — To prevent the enemy from using or salvaging this equipment for his benefit.
WHEN — When ordered by your commander.
HOW —1. Smash — Use sledges, axes, handaxes, pickaxes, hammers, crowbars, heavy tools.
2. Cut — Use axes, handaxes, machetes.
3. Burn — Use gasoline, kerosene, oil, flame throwers, incendiary grenades.
4. Explosives — Use firearms, grenades, TNT.
5. Disposal — Bury in slit trenches, fox holes, other holes. Throw in streams. Scatter.
USE ANYTHING IMMEDIATELY AVAILABLE FOR DESTRUCTION OF THIS EQUIPMENT
WHAT —1. Smash — Crystals, meters, plugs, tubes, tuning controls, capacitors, resistors, sockets, insulators, microphones, headsets, relays, gas engine, and generator.
2. Cut — Cords, wiring, and cables.
3. Burn — Circuit labels, technical manuals, all papers, cords, wiring, cables, capacitors, resistors, and nameplates.
4. Bend — Antenna sections, panels, mounting, and nameplates.
5. Bury or scatter — All of the above pieces after breaking and burning.
DESTROY EVERYTHING
VIU
SAFETY NOTICE
Voltages as high as 2,600 volts are used in the operation of this equipment. These voltages are •dangerous to life.
Do not change tubes or make adjustments inside the set with the high voltage supply ON.
All panels giving access to voltages above 450 volts are provided with interlocks to shut off the dynamotor when opened. A few service checks must be made inside the set with the high voltage on. When making these checks, always have the immediate presence and assistance of another person capable of rendering aid. Keep one hand in your pocket while making high voltage measurements. This will prevent touching the electrical circuit with more than one part of the body at one time.
Be sure that high-voltage plate circuits are dead before performing preventive maintenance on this equipment. High-voltage capacitors in power supplies must be discharged manually before performing preventive maintenance operations.
Servicing should be done with the vehicular battery circuit open. Shorting this battery circuit will cause a flash and severe burns unless the power is turned off.
First Aid for Electric Shock
TL 15339
Radio-frequency voltages as high as 25,000 volts may develop on the antenna of this radio set. Do not touch the antenna while the set is turned on.
Do not add gasoline to the vehicle fuel tank when the transmitter is on. Radio-frequency voltage may cause a spark resulting in an explosion. Turn off the radio transmitter and KEEP it off until refueling is finished.
Do not add gasoline to the vehicle fuel tank when the transmitter is on. Radio-frequency voltage present on the chassis of the vehicle may cause a spark resulting in an explosion. Turn off the radio transmitter and KEEP it off until refueling is finished.
ix
FIRST AID FOR ELECTRIC SHOCK
I. Rescue
In case of electric shock, shut off the high voltage at once and ground the circuits. If the high voltage cannot be turned off without delay, free the victim from contact with the live conductor as promptly as possible. Avoid direct contact with either the live conductor or the victim’s body. Use a dry board, dry clothing, or other nonconductor to free the victim. An ax may be used to cut the high-voltage wire. Use extreme caution to avoid the resulting electric flash.
2. Symptoms
a. Breathing stops abruptly in electric shock if the current passes through the breathing center at the base of the brain. If the shock has not been too severe, the breathing center recovers after a while and normal breathing is resumed, provided that a sufficient supply of air has been furnished meanwhile by artificial respiration.
b. The victim is usually very white or blue. The pulse is very weak or entirely absent, and unconsciousness is complete. Burns are usually present. The victim’s body may become rigid or stiff in a very few minutes. This condition is due to the action of electricity and is not to be considered rigor mortis. Artificial respiration must still be given, as several such cases are reported to have recovered. The ordinary and general tests for death should never be accepted.
3. Treatment
a. Start artificial respiration immediately. At the same time send for a medical officer, if assistance is available. Do not leave the victim unattended. Perform artificial respiration at the scene of the accident, unless the victim’s or operator’s life is endangered from such action. In this case only, remove the victim to another location, but no farther than is necessary for safety. If the new location is more than a few feet away, artificial respiration should be given while the victim is being moved. If the method of transportation prohibits the use of the Shaeffer prone pressure method, other methods of resuscitation may be used. Pressure may be exerted on the front of the victim’s diaphragm, or the direct mouth to mouth method may be
used. Artificial respiration, once started, must be continued, without loss of rhythm.
b. Lay the victim in a prone position, one arm extended directly overhead, and the other arm bent at the elbow so that the back of the
TL I5338A
X
A
B
C
D
hand supports the head. The face should be turned away from the bent elbow so that the nose and mouth are free for breathing, as shown in A and B.
c. Open the victim’s mouth and remove any foreign bodies, such as false teeth, chewing gum, or tobacco. The mouth should remain open, with the tongue extended. Do not permit the victim to draw his tongue back into his mouth or throat.
d. If an assistant is available during resuscitation, he should loosen any tight clothing to permit free circulation of blood and to prevent restriction of breathing. He should see that the victim is kept warm, by applying blankets or other covering, or by applying hot rocks or bricks wrapped in cloth or paper to prevent injury to the victim. The assistant should also be ever watchful to see that the victim does not swallow his tongue. He should continually wipe from the victim’s mouth any frothy mucus or saliva that may collect and interfere with respiration.
e. The resuscitating operator should straddle the victim’s thighs, or one leg, in such a manner that the—
(1) Operator’s arms and thighs will, be vertical while applying pressure on the small of the victim’s back (C).
(2) Operator’s fingers are in a natural position on the victim’s back with the little finger lying on the last rib.
(3) Heels of the hands rest on either side of the spine as far apart as convenient without allowing the hands to slip off the victim (A).
(4) Operator’s elbows are straight and locked.
f. The resuscitation procedure is as follows:
(1) Exert downward pressure, not exceeding 60 pounds, for 1 second.
(2) Swing back, suddenly releasing pressure, and sit on the heels (D).
(3) After 2 seconds’ rest, swing forward again positioning the hands, and apply pressure for another second (B and C).
g. The forward swing, positioning of the hands, and the downward pressure should be accomplished in one continuous motion, which
requires 1 second. The release and backward swing require 1 second. The addition of the 2-second rest makes a total of 4 seconds for a complete cycle. Until the operator is thoroughly familiar with the correct cadence of the cycle, he should count the seconds aloud, speaking distinctly and counting evenly in thousands. Example : one thousand and one, one thousand and two, etc.
h. Artificial respiration should be continued until the victim regains normal breathing, or is pronounced dead by a medical officer. Since it may be necessary to continue resuscitation for several hours, relief operators should be used if available.
4. Relieving Operator
The relief operator kneels beside the operator and follows him through several complete cycles. When the relief operator is sure that he has the correct rhythm, he places his hands on the operator’s hands without applying pressure. This indicates to the operator that he is ready to take over. On the backward swing, the operator moves and the relief operator takes his position. The relieved operator follows through several complete cycles to be sure that the new operator has the correct rhythm. He remains alert to take over instantly if the new operator falters or hesitates on the cycle.
5. Stimulants
a. If an inhalant stimulant is used, such as aromatic spirits of ammonia, the individual administering the stimulant should first test it himself to see how close he can hold the inhalant to his own nostrils for comfortable breathing. Be sure that the inhalant is not held any closer to the victim’s nostrils, and then for only 1 or 2 seconds every minute.
b. After the victim has regained consciousness, he may be given hot coffee, hot tea, or a glass of water containing i/2 teaspoon of aromatic spirits of ammonia. DO NOT GIVE ANY LIQUIDS TO AN UNCONSCIOUS VICTIM.
Cautions: 1. After the victim revives, keep him lying quietly. Any injury a person may have received may cause a condition of shock. Shock is present if the victim is pale and has a cold sweat, his pulse is weak and rapid, and his breathing is short and gasping.
2. Keep the victim lying flat on his back, with
xi
his head lower than the rest of his body and his hips elevated. Be sure that there is no tight clothing to restrict the free circulation of blood or hinder natural breathing. Keep him warm and quiet.
3. A resuscitated victim must be watched
carefully as he may suddenly stop breathing. NEVER LEAVE A RESUSCITATED PERSON ALONE UNTIL IT IS CERTAIN THAT HE IS FULLY CONSCIOUS AND BREATHING NORMALLY.
xii
ch^r 1
This manual supersedes TM 11-281, 4 September 1843; TB 11-281-1, 13 October 1944, and TB 11-281-2, 25 November 1944.
CHAPTER J
GENERAL
Section I. DESCRIPTION
I. General
a. This manual covers Radio Sets SCR-399-A and SCR-499-A. There are no differences in the operating components and power sources of the two sets, but Radio Set SCR-399-A is usually installed as a mobile station (fig. 1) and Radio Set SCR-499-A is ordinarily set up as a fixed station (fig. 2). To facilitate its use as a mobile station, Radio Set SCR-
399-A is shipped with the operating components and the power source installed in Shelter HO-17-A and Trailer K-52-( ), respectively. A shelter and trailer are not provided with Radio Set SCR-499-A, since it is not intended for mobile use. Its components are shipped in 23 boxes from which they can be unpacked and set up as a fixed station at any suitable site.
-------- receiving antenna MAST SECTIONS
MS-51,52,53
^Transmitting antenna s' / \
MAST SECTIONS ________-/ I
MS-49,50,51,52,53-" / I
/ //'f/ MAST BASE MP-48
’MAST BASE MP-47-A* —-X-- / --- ■__________-
/ , \ I 1 // ______. MAST BASE MP-50-A
SHELTER HO-I7-Ay* i V 7/
_____/] / / \ \ 7/ TRAILER K-52-C )WlTH \ / \ / \ // POWER UNIT PE-95-( )
ayL Z[^ M j| /\ / -
’* A J/^\ w r
TRUCK 2jTON 6X6 CORD CO-335 CORD CO-3IO TLI732Q
Figure 1. Radio Set SCR-399-A installed as a mobile station.
3
4
’ •• | j ANTENNA TUNING ^’ e' i
J CHEST CH-feO-A UNIT BC*939*A
/ / RADIO TRANSMITTER ?■?
/ / BC-6I0-E
If CHEST CH-I2I-A / / / CHEST
iSP’flBi / CH-88-a
£/-■ • -I. r---------k
—x " vT?- , '■_ i? • chest
***r\ * 1 U c~'’1 -’9
" ’■■*•*>*x BK-___________-
fix L, - ...*• ■ ;S
f t ' < '-■■ is &k ■
•<3 ' ;hest . . _ w. £se< xwo
CH-IO9-A |Jk ! I |y- b',
U7 Uf \ In* • ' ' BL--
// ’ \ • j x£*^HEATER I / 1 I W i
n -«;RA-63-( ) • T I 1 ■
<%■>’ ■S-*-;;-'?-‘* 1 r frame j
FM-59-A
—■ ?—:
CHEST CH-89-A / I r l 15 • > ■■ 0 ,j
Figure 2. Radio Set SCR-499-A, operating and accessory components arranged as a fixed station.
b. The following Technical Manuals are issued with the radio sets and contain detailed information on the various components as listed below:
TM 11-333, Telephone EE-8-( ).
TM 11-850, Radio Receivers BC-312-( ), BC-314-( ), BC-342-( ), and BC-344-( )•
TM 11-904, Power Unit PE-95-( ).
TM 11-300, Frequency Meter Set SCR-211-( ).
Parts List for Shelter HO-17-A.
c. Trailer K-52-( ) and Power Unit PE-95-( ), used with Radio Set SCR-399-A, are also supplied with Radio Sets SCR-299-C and -D.
d. Official nomenclature followed by ( ) is used in this manual to indicate reference to all models of the item of equipment. Official nomen-
clature followed by (*) refers to all models included in one Technical Manual. Therefore, Rectifier RA-63-(*) refers to Rectifiers RA-63-A and -C, treated together in this manual.
2. Radio Set SCR-399-A
Radio Set SCR-399-A is a relatively high-power radio communications station. Under all conditions of atmosphere and terrain, the radio set will provide voice or c-w (continuous-wave) communication over a range of more than 100 miles from a stationary position, or while moving at high speed. For mobile use, Shelter HO-17-A should be mounted on a 2^-ton, 6x6, cargo truck. (See fig. 1.) Two seats in the truck cab carry the driver and his alternate. In the shelter (fig. 3), two operators may sit at the radio station operating positions. Power Unit PE-95-( ) may be started and stopped by remote control or at the trailer. The transmitting
5
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CH-121-A ~~—TUBE
’■ ' ■ ' • • . ' ** / * ■ =:• * "’"j
’ CHEST
| i^H-120-^ (LAMP FIXTURE ' f^EST |
j CH-8S-A|
• ■r ' Sr . I antenna b
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.« -■. ‘ &*.. w-
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BBT.-- TRANSMITTER
*> CHEST 3 ^■bBc eio-t
wr ,k y* ^RSSh^NIM CH-I09-A 5 . -
covers f to
igjgL^ J BG-ylAi-A k J > “EATER’
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FBB 00-335/ ■'• " ’ RA-63-( )... Ml DR-4 Mlyvjt
r / ' - I IP • ■
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■ * ' CHEST J I
| CH-89-AX^J - 1 .
Figure 3. Radio Set SCR-399-A
installed in Shelter H0-17-A.
and receiving controls, tuning units, coils, crystals, and spare parts are all within reach of the operating positions. In cold weather, an electric heater maintains moderate temperature within the shelter. In warm weather, the motor-driven heater fan and a ventilating blower provide adequate air circulation. (See fig. 4.) Chest CH-89-A (seat bench) has a 4-inch cushion on each of the four lids covering its spare parts compartments, and provides sleeping quarters for one person. An additional shelter and sleeping quarters can be made with the wooden frame and tarpaulin from the trailer.
3. Radio Set SCR—499-A
The components of Radio Set SCR-499-A are the same as those of Radio Set SCR-399-A, except that a shelter and trailer are not provided. The components can be quickly assembled and set up as a field station in a tent, a shelter, or in the open. The installed radio set can be easily dismantled into a number of component parts, each of which is small enough for air transportation to a new site. Canvas covers are issued to provide protection for components while they are in transit, as well as to protect them if the station is set up in the open.
6
til > in ti > ml
!;:?•<■■•' CHEST f VENTILATING
■■I ch-88-aWMk ;L^2wer « llifa ____■_[ _________’ ■
—......■... ""?».If'»
---—fe . - / ■ 3 FAIRLEAD &
I ' ’’w ’
4*. z ' ’ - ■ ^k-S'4'A ■•■■ -
I I
CHEST > f _-■ ’
_ CH-H9-A ir\ fev'jLII
j I u’ ’ I
W- - 1 ^IK^!
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Ims
9ft ^Sk. ,- •< - ■ • ~' >■ m * a
gME
CH-89-A K W ■
Ib
sSHES HE& - i
hi 11,[a
Figure 4. Shelter H0-17-A—interior view of right (or curb) side.
4. Technical Characteristics
a. Radio Transmitter BC-610-E (fig. 5).
Frequency range fi
Three channels (1, 2, and 3)........................................
Circuit.................................................................
Types of signals transmitted............................................
2 me to 18 me
master oscillator-power amplifier (mopa)
c-w and voice
Distance range :2
C-w: Stationary ...........................................250 mi
Moving................................................250 mi
Voice: Stationary............................................100 mi
Moving....... ., .....................................100 mi
Type of modulation................................................amplitude
Number of tubes...................................................16
’Refer to the frequency spectrum chart, figure 6.
2Use the best operating frequency for the time of day and season of year.
7
JTLI5940
Figure 5. Radio Transmitter BC-610-E with Antenna Tuning Unit BC—939-A in position.
Antennas:
Whip antenna...................................................
Extended whip antenna......................................
15 ft long. Consists of Mast Sections MS-49 to MS-53, inclusive
25 ft long. Add 1 or 2 Mast Sections MS-54 to Mast Section MS-53
25-100 ft long kit
Straight wire antenna.............................................
Doublet antenna...................................................
Power output:
C-w operation......................................................
Voice operation ...................................................
400 watts (approx)
300 watts (approx)
8
Power input:
115-volt, 50/60-cycle ac Power source...............
Weight.....................
1,700-2,000 watts
PE-95-( ) or commercial
401 lb
FREQUENCY SPECTRUM: cMeqacqc&e
o .5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 12.5 180
1/ i i i i I । i •" r~ i' i 1 i • i m m / cpd.iqq.a transmitter 1.5-12.5 mc / /
\ OUn loo A RECEIVER 1.5-18.0 MC '
/ CCD-QQQ-A CPD-liOQ-A transmitter 2.0-ie.o mc ) \
OUn Ooo r\ Obn *too A receiver i.5-i8.omc f 2
rj L । : j rn 3
CP D-HAQ- f 1 TRANSMITTER 2.0-8.0 MC
Ovn CC77 v / RECEIVER 1.5 18.0 MC JHB tK&ffiwSSx
T - — | । । , ! ■ “
ff.- 1 . ■ - I / ern cnn .(I transmitter 3.8-6.5 mc \
^□bK oy*r \/ RECEIVER 3.8-6.5MC^
NOTE '• avt&u/s a£&uj A------- 1
TlzafOfttcO&'t, ftanqf ifei£ x.- /cr'D.OQ2i-f vRAN5MiTrER3e 58“^\ I 1 ’
7& avuttivs wdccdOe' X——— /
7fe nanyed n£c€a/&M-. 4QE3I a ; /
Ciee arttittitts , / ero-Kii-/ transmitter 3.0-6.0 mc x | ] I
exTChttzd /ia;tqeMC. and receiver 100'156'MC ’rsoooa
Figure 6. Frequency spectrum chart.
b. Radio Receivers BC-312-( ) andBC-342-( ).
Frequency range: Band A ...........................................................
Band B .......................................................
Band C .......................................................
Band D .......................................................
Band E .......................................................
Band F .......................................................
Circuit...........................................................
Types of signals which can be received............................
Number of tubes...................................................
Intermediate frequency ...........................................
Method of calibration.............................................
Antenna (whip) ...................................................
1.5 mc to 3 mc
3 mc to 5 mc
5 mc to 8 mc
8 mc to 11 mc
11 mc to 14 mc 14 mc to 18 mc superheterodyne c-w, tone, and voice
9
470 kc
Frequency Meter Set SCR-211-( )
Mast Base MP-48 mounted in Mast Base Bracket MP-50 and Mast Sections MS-51 to MS-53
9
Power input:
Radio Receiver BC-312-( )...........................................
Radio Receiver BC-342-( )...........................................
Power source ...........................................................
Weight.........................................................
50-55 watts
70-85 watts
12-volt battery for Radio Receiver BC-312-( )
110-volt 50/60 cycle ac for Radio Receiver BC-342-( )
40-50 lb (each)
5. List of Components and Packaging Data
The following is an alphabetical list of items issued with Radio Sets SCR-399-A and SCR-499-A. Note. Running spares are for initial issue only and are not to be requisitioned as a kit or group as shown in
the list of components.
Radio Set Radio Set
SCR-399-A SCR-499-A Component
4 4 Antenna guy assembly (receiver)
2 2 Antenna guy assembly (transmitter)
1 1 Antenna Tuning Unit BC-939-A
1 1 Antenna doublet kit
1 1 Axle RL-27-B
12 12 Battery BA-30; spare
2 2 Battery, storage; 6-volt
2 2 Box BX-19-A
1 1 Box BX-34-B; with crystals
6 0 Bracket for gasoline can
2 2 Brush, high-voltage; for dynamotor of Radio Receiver BC-312-( ) ;
2 2 Brush, low-voltage; for dynamotor of Radio Receiver BC-312 -( ) ; spare
1 1 Bumper clamp (for Cord CO-335)
1 1 Chest CH-88-A (wall)
1 1 Chest CH-89-A (seat bench)
1 1 Chest CH-109-A (12-volt battery)
1 0 Chest CH-112-A
0 1 Chest CH-112-B
1 0 Chest CH-119-A (wall)
0 1 Chest CH-119-B (wall)
1 1 Chest CH-120-A (main operating)
1 1 Chest CH-121-A (auxiliary)
1 1 Cord CX-141/MRQ-2; Junction Box JB-70-A to Speech Amplifier BC-614-E; 3-foot
1 1 Cord CX-143/MRQ-2 (main audio) ; 55-inch (LS-3 branch 21 inches, BC-342 branch 10 inches)
0 1 Cord CD-201-A; Key J-37 to Junction Box JB-70-A
1 1 Cord CX-140/MRQ-2 (auxiliary audio) ; 53-inch (BC-312-( ) branch 11 inches)
1 1 Cord CO-313 (a-c extension) ; 100-foot
1 1 Cord CO-314 (a-c connection) ; 3-foot
2 . Cord CO-316 (power and control) ; 11-foot; 1 in use, 1 spare Cord CD-318-A; for Microphone T-30
1
2 1 Cord CO-335 (power and control) ; 14-foot; 1 in use, 1 spare (SCR-399-A), no spare (SCR-499-A)
2 2 Cord CD-564 (power) ; 3-foot; 1 in use, 1 spare
2 2 Cord CD-565 (control and power) ; 4-foot; 1 in use, 1 spare
2 2 Cord CD-566 (control) ; 4-foot; 1 in use, 1 spare
4 4 Cord CD-605; for Headset HS-30
1 1 Cord CD-652 (power and control extension) ; 100-foot
0 1 Cord CD-1117; for Loudspeaker LS-3
1 1 Cord CD-1177 (audio patch) ; 2-foot
1 1 Cord CD-659 (power) ; 12-volt battery to receiver; shelter connection; 6-foot
10
Radio Set SCR-399-A
1
2
1
1
1
1
1
1
1
2 (sets)
6
1
1
1
1
6
4
7 (sets)
Radio Set SCR-499-A
1
2
2
1
1
1
1
1
1
1
2 (sets)
6
1
0
1
1 .
14
5
7 (sets)
7 7
1 1
4 4
1 1
1 1
1 1
3 3
1 0
10 7
2 2
2 2
1 1
8 8
2 (sets)
1 0
2 2
2 2
2 2
3 3
0 1
3 3
4 4
4 4
6 6
6 6
6 6
2 2
2 2
1 1
1 0
0 1
Component
Cord CD-690 (power) ; 12-volt battery to receiver; field connection; 6-foot
Cord CD-763 (transmitter power) ; 4-foot; 1 in use, 1 spare
Cord CD-764 (transmitter control) ; 15-foot; 1 in use, 1 spare
Cover BG-141-A; for Chest CH-89- ( )
Cover BG-142-A; for Chest CH-119- ( )
Cover BG-143-A; for Chest CH-121- ( )
Cover BG-144-A; for Chest CH-88-( )
Cover BG-145-A; for Chest CH-120- ( )
Cover BG-146-A; for Radio Transmitter BC-610-E and Antenna
Tuning Unit BC-939-A
Counterpoise CP-15-B
Crystals in Crystal Holders FT-171-B
Drums, gasoline; galvanized steel; with handle; capacity 5 gallons
Frame FM-59-A; for Reels DR-4
Frame FM-62-A; for spare tire
Frequency Meter Set SCR-211-( ) ; with spare tubes and batteries
Fire extinguisher; Randolph Laboratories model FF-4
Fuse FU-21-A; for Radio Receivers BC-312-( ) and BC-342-( ) ;
2 in use, 4 spare (SCR-399-A), 12 spare (SCR-499-A)
Fuse FU-27; for Radio Receiver BC-342-( ) ; 1 in use, 3 spare (SCR-399-A), 4 spare (SCR-499-A)
Fuses for Radio Transmitter BC-610-E and Speech Amplifier BC-614-E ; 1 in use, 6 spare, consisting of—
2—25-ampere fuses
1—20-ampere fuse
1— 5-ampere fuse
1— 3-ampere fuse
Fuse; 25-ampere; 1 in use, 6 spare (used in Chest CH-109-A)
Heater, electric; Electromode model AA-15
Headset HS-30-( ) ; 2 in use, 2 spare
Holder for fire extinguisher
Junction Box JB-60-A
Junction Box JB-70-A
Key J-37; 2 in use, 1 spare
Key J-45
Lamp; 50-watt; 115-volt; 3 in use, 7 spare for SCR-399-A; 2 in use, 5 spare for SCR-499-A
Lamp; 50-watt; 12-volt; spare
Lamp, trouble, emergency; 115-volt; with 25-foot extension cord and 50-watt lamp
Lamp, trouble, emergency; 12-volt; with 25-foot extension cord and 50-watt lamp
Lamp LM-27; for radio receivers; 4 spare
Lamp; for Trailer K-52- ( ) ; spare
Lamp fixture (shelter)
Lamp fixture (operating chests)
Loudspeaker LS-3
Mast Base MP-47-A; 1 in use, 1 spare
Mast Base MP-48; 2 in use, 1 spare
Mast Base Bracket MP-59-A; for Mast Base MP-47-A
Mast Base Bracket MP-50-A; for Mast Base MP-48; 2 in use, 1 spare
Mast Section MS-49 ; 1 in use, 3 spare
Mast Section MS-50; 1 in use, 3 spare
Mast Section MS-51; 3 in use, 3 spare
Mast Section MS-52; 3 in use, 3 spare
Mast Section MS-53; 3 in use, 3 spare
Mast Section MS-54
Microphone T-50; dynamic; 1 in use, 1 spare
Microphone T-17
Microphone T-30 (throat)
Microphone T-45
II
Radio Set SCR-399-A
3
1 (set)
Radio Set SCR-499-A
3
1 (set)
1 each
1 each
20
4
4
1 each
7 each
1 each
1 each
20
4
4
1 each
7 each
1
1
1
1
1
2
1
1
1
1
2
1
2
2
2
2
2
2
1
1
1
1
1
1
1
1
2
1
1
0
0
2
3 0
0
2
2
2
2
2
2 0
1
1
Component
Nozzle; for gasoline drums
Parts, spare:
For Radio Transmitter BC-610-E and Speech Amplifier BC-614—E consisting of 33 percent of the number of the following parts used in the radio transmitter and speech amplifier, but not less than 1 each
Fixed and variable resistors
Fixed capacitors
R-f choke coils
Every type relay used in Speech Amplifier BC-614-E, Radio Transmitter BC-610-E, and Junction Box JB-70-A
Every type switch used, except band switch
Each ceramic insulator used for the power-amplifier variable capacitor
Each ceramic insulator used for the power-amplifier coil unit Each ceramic spacer used for the power-amplifier coil unit Circuit breaker for Junction Box JB-70-A
Every pilot lamp and dial lamp used in Radio Transmitter BC-610-E and Speech Amplifier BC-614-E (For itemized list of resistors, capacitors, and chokes supplied as spares, see the maintenance parts list, par. 198)
Power Unit PE-95-( ) ; including tools, 2 batteries (6-volt), and spare parts
Radio Receiver BC-312-( ) ; including Mounting FT-162 and 2 Mountings FT-178
Radio Receiver BC-342-( ) ; including Mounting FT-162 and 2 Mountings FT-178
Radio Transmitter BC-610-E; including 24 tuning units, 14 coil units, 2 Capacitors CA-423, and 2 sets tuning charts
Rectifier RA-63-(*)
Reels DR-4
Rope RP-5; 50-foot
Speech Amplifier BC-614-E
Shelter HO-17-A (mobile)
Speaking tube
Stake GP-8; with 10 feet of copper braid
Strap ST-19-A
Table frame; for mounting Chests CH-120-A and CH-121-A in Shelter H0-17-A
Part List for Shelter HO-17- ( )
TM 11-281; for Radio Sets SCR-399-A and SCR-499-A
TM 11-904; for Power Unit PE-95-( )
TM 11-850; for Radio Receivers BC-312-( ) and BC-342-f )
TM 11-300 ; for Frequency Meter Set SCR-211-( )
TM 11-333; for Telephone EE-8-( )
Telephone EE-8-( )
Tire and wheel; spare for truck and trailer
Tool equipment TE-48
Set tools and repair equipment consisting of—
1 Analyzer BC-1052-E
1 can carbon tetrachloride
1 drill, electric; 110-voltac; ^-inch
1 drill, twist; carbon-steel; %-inch
1 drill, twist; carbon-steel; i/2-inch
2 pair pliers
1 hammer, claw; 16-ounce
1 set hardware, assorted
1 hydrometer; for storage batteries
2 battery lift strap
5 pounds solder, rosin-core
1 can machine oil
1 Soldering Iron TL-120
3 rolls tape, friction; Va-inch
12
Radio Set SCR-399-A
Radio Set SCR-499-A
4 4
16 16
4 4
4 4
2
6
4
6
2
2
6
5
5
2
2
2
2
6
1
1
1
1
2
12
7
12
4
4
10
8
8
4
4
3
3
7
10
1 0
1
1
Component
1 roll tape, rubber; 1/9-inch
1 Torch TL-130
2 No. 6-32 Allen head wrench
2 No. 8-32 Allen head wrench
2 Allen head wrench for 14-inch screw
1 sheet crocus cloth
Tube VT-65-A (JAN-6C5G) ; for Radio Receivers BC-312-( ) and BC-342-( ) ; 4 installed, 4 spare
Tube VT-66-A (JAN-6F6G) ; for Radio Receivers BC-312-( ) and BC-342-( ) ; 2 installed, 2 spare
Tube VT-86-A (JAN-6K7G) ; for Radio Receivers BC-312-( ) and BC-342-( ) ; 8 installed, 8 spare
Tube VT-87-A (JAN-6L7G) ; for Radio Receivers BC-312-( ) and BC-342-( ) ; 2 installed, 2 spare
Tube VT-88-A (JAN-6R7G) ; for Radio Receivers BC-312-( ) and BC-342-( ) ; 2 installed, 2 spare
Tube VT-97 (JAN-5W4) ; for Radio Receiver BC-342-( ); 1 installed, 1 spare
Tube VT-46-A (JAN-866-A/866) ; for Radio Transmitter BC-610-E ; 2 installed, 4 spare (SCR-399-A), 10 spare (SCR-499-A)
Tube VT-95 (JAN-2A3) ; for Radio Transmitter BC-610-E; 2 installed, 2 spare (SCR-399-A), 5 spare (SCR-499-A)
Tube VT-100 (JAN-807) ; for Radio Transmitter BC-610-E; 2 installed, 4 spare (SCR-399-A), 10 spare (SCR-499-A)
Tube VT-107 (JAN-6V6) ; for Radio Transmitter BC-610-E; 1 installed, 1 spare (SCR-399-A), 3 spare (SCR-499-A)
Tube VT-115 (JAN-6L6) ; for Radio Transmitter BC-610-E; 1 installed, 1 spare (SCR-399-A), 3 spare (SCR-499-A)
Tube VT-139 (JAN-OD3/VR-150) ; for Radio Transmitter BC-610-E; 3 installed, 3 spare (SCR-399-A), 7 spare (SCR-499-A)
Tube VT-145 (JAN-5Z3) ; for Radio Transmitter BC-610-E; 2 installed, 3 spare (SCR-399-A), 6 spare (SCR-499-A)
Tube VT-218 (JAN-100-TH) ; for Radio Transmitter BC-610-E;
2 installed, 3 spare (SCR-399-A), 6 spare (SCR-499-A)
Tube VT-220 (JAN-250-TH) ; for Radio Transmitter BC-610-E;
1 installed, 1 spare (SCR-399-A), 3 spare (SCR-499-A)
Tube VT-80 (JAN-80) ; for Speech Amplifier BC-614-E; 1 installed, 1 spare (SCR-399-A), 3 spare (SCR-499-A)
Tube VT-103 (JAN-6SQ7) ; for Speech Amplifier BC-614-E; 1 installed, 1 spare (SCR-399-A), 2 spare (SCR-499-A)
Tube VT-233 (JAN-6SR7) ; for Speech Amplifier BC-614-E; 1 installed, 1 spare (SCR-399-A), 2 spare (SCR-499-A)
Tube VT-94 (JAN-6J5) ; for Speech Amplifier BC-614-E; 2 installed, 2 spare (SCR-399-A), 5 spare (SCR-499-A)
Tube VT-231 (JAN-6SN7GT) ; for Speech Amplifier BC-614-E;
3 installed, 3 spare (SCR-399-A), 7 spare (SCR-499-A)
Typewriter, portable; with telegrapher’s keyboard; includes case
Trailer K-52-( )
Wire, antenna; 100-foot
Wire W-110-B (on Reels DR-4) ; 4,800-foot.
cS""paragraph 27 for Packing data on Radio Set SCR-399-A and Table II (par. 28) for data on Radio Set oLK-4yy~ A.
6. Major Components
The major components of Radio Set SCR-399-A are furnished installed in a shelter and trailer. Shelter H0-17-A contains the components which comprise the radio station, and should be mounted on a 2i/2-ton, 6x6 cargo truck for mobile use. Trailer K—52—( ) contains
Power Unit PE-95-( ). The major components of the set are:
Radio Transmitter BC-610-E (par. 7) Speech Amplifier BC-614-E (par. 8)
Junction Box JB-70-A (par. 9)
Radio Receivers BC-342-( ) and BC-312-( ) (par. 10)
13
Antenna Tuning Unit BC-939-A (par. U)
Antenna (par. 12)
Power Unit PE-95-( ) (par. 13)
R-FOUTPUT
terminals
R-F CHASSIS
MODULATOR CHASSIS
AUDIO INPUT
FROM SPEECH AMPLIFIER BG-6I4-E
A-C POWER
SUPPLY FROM JUNCTION BOX JB-7O-A
■
POWER CHASSIS
iJ TL159221
Figure 7. Radio Transmitter BC-610-E chassis assembly—rear view.
14
7. Radio Transmitter BC-610—E (fig. 7)
a. The transmitter assembly is made up of three chassis. The top chassis is referred to as the r-f (radio-frequency) section and includes all of the r-f components. The center chassis is called the modulator section, since it contains most of the audio and modulator equipment. The bottom chassis includes the high-voltage powersupply and overload relay. It is called the powersupply section. The three chassis are assembled into a sheet steel cabinet with a front panel upon which the external controls and metering instruments are mounted. (See fig. 5.)
b. The transmitter is bolted to the cradle frame shock-mounting base which is anchored to the floor with wrench nuts. The weight of the transmitter is 450 pounds; installed, the over-all weight is approximately 500 pounds.
c. The frequency range of the transmitter is 2 to 18 megacycles. This wide frequency range is covered by means of three sets of plug-in tun
ing units, eight to a set; two sets of plug-in coil units, seven to a set; and Capacitor CA-423. Each tuning unit and associated coil unit, or coil unit with capacitor, covers a portion of the range. (See table III.) The frequency is controlled by the master oscillator or the crystal oscillator, depending on the position of the M.O.-XTAL switch on the tuning unit. The transmitter can be used for radiotelegraph and radiotelephone communication. At frequencies below 8 megacycles the power output of the transmitter exceeds 400 watts on continuous wave and 300 watts on voice. The power output is somewhat less at higher frequencies. The transmitter will operate satisfactorily with input power of 1,700 to 2,000 watts from a 115-volt, 50/60 cycle a-c (alternating-current) source.
8. Speech Amplifier BC-614-E (fig. 8)
a. The amplifier is shock-mounted to the top
Figure 8. Speech Amplifier BC-614-E and Junction Box JB-70-A in Chest CH-120-A —front view.
15
of Junction Box JB-70-A in Chest CH-120-A. For convenient removal, four snap fasteners are used to anchor the speech amplifier to its shock-mounting. The weight of the speech amplifier, less shock-mount, is approximately 31 pounds.
b. The speech amplifier raises the microphone output to a level suitable for voice modulation of the transmitter. It also provides sidetone for headset monitoring of c-w transmissions. Speech Amplifier BC-614-E contains its own plate and filament supply unit which draws approximately 40 watts from the 115-volt, 50/60-cycle, a-c source.
9. Junction Box JB-70-A
a. The junction box is a junction point for most of the cords and cables which interconnect the various components. Power and control cords plug into either the bottom (through the bottom of Chest CH-120-A) or the side of the junction box. Key and headset connections are plugged into the jacks on the front panel.
b. Junction Box JB-70-A serves as a control center for the station. The front panel controls (fig. 8) provide for:
(1) Starting or stopping Power Unit PE-95—( ).
(2) Resetting the circuit breaker in the power mains.
(3) Selection of 12-volt battery source.
(4) Control of transmission and reception.
(5) Remote control operation.
(6) Choice of manual or automatic receiver disabling.
(7) Choice of receiver output to headset.
(8) A sidetone signal to monitor transmission during c-w operation.
10. Radio Receivers BC—342—( )
and BC-3l2-( )
a. Radio Receiver BC-342-( ). Radio Receiver BC-342-( ) is in Chest CH-120-A. It is anchored by Mountings FT-162 and FT-178. This receiver is powered by the 115-volt, 50/60-cycle, a-c source. It is capable of receiving c-w, voice-modulated, or tone-modulated signals over an r-f range of 1.5 to 18 megacycles.
b. Radio Receiver BC-312-( ). Radio Receiver BC-312-( ) is anchored in Chest CH-121-A by Mountings FT-162 and FT-178. It is a d-c (direct-current) receiver with the same receiving characteristics as Radio Receiver BC-342-( ), except that a crystal filter is not in
cluded. The battery in Chest CH-109-A or the battery in Power Unit PE-95-( ) may be used as a source of power. For further information on the receivers, consult TM 11-850.
I I. Antenna Tuning Unit BC-939—A (fig. 9) The tuning unit is mounted on top of Radio Transmitter BC-610-E and is fastened securely by four wingnuts. It couples the output of the transmitter to the transmitting antenna. All controls are mounted on the front panel. The unit weighs 48 pounds.
Caution: WHEN THE TRANSMITTER IS IN OPERATION DO NOT TOUCH ANY PART OF THE ANTENNA TUNING UNIT, EXCEPT THE FRONT PANEL CONTROLS.
12. Antenna System
The antenna system consists of a transmitting antenna and two receiving antennas. (See fig. L)
a. Transmitting Antenna. Mast Base MP-47-A and Mast Sections MS-49 to MS-53, inclusive, form the transmitting antenna (whip). Mast Base Assembly MP-47-A is mounted through the roof of Shelter H0-17-A and is connected to Antenna Tuning Unit BC-939-A. Mast Section MS-53 is screwed into the mast base to form the lowest section, and Mast Section MS-49 forms the top section of the assembly. For mobile use, the antenna is bent backward (fig. 1) and held in a horizontal position by an insulated guy to the rear of the roof. This provides clearance and keeps the antenna from whipping about while the vehicle is in motion. The snap-catches on the guy permit the release of the antenna to a vertical position to provide more uniform radiation while the set is stationary. When the transmitting antenna is operated vertically, one or two additional Mast Sections MS-54 may be added. A doublet antenna is furnished for operation from a fixed site, since it provides a considerably greater range of communication than the whip antenna. (See par. 123.) A straight wire antenna can be used; 100 feet of wire is issued for this purpose. (See table IV.)
Caution: EXTREMELY DANGEROUS VOLTAGES ARE PRESENT ON THE ANTENNA AND ITS INSULATORS DURING TRANSMISSION. DO NOT TOUCH.
b. Receiving Antenna. Mast Base MP-48, mounted in Mast Base Bracket MP-50-A, and Mast Sections MS-51 to MS-53 make up a re-
16
Figure 9. Antenna Tuning Unit BC-939-A.
ceiving antenna. Two receiving antennas are used, since each receiver operates from a separate whip antenna. The antennas are mounted on the upper rear corners of Shelter H0-17-A. (See fig. 1.)
13. Power Unit PE—95—( )
Power Unit PE-95-( ) is a complete, self-contained, gasoline-driven generating unit, capable of delivering 5 kilowatts of a-c power (singlephase 60-cycle at 115 volts) for the operation of Radio Set SCR-399-A, Radio Set SCR-499-
A, or other equipment. Power Unit PE-95-( ) can be:
a. Installed in Trailer K-52-( ). (See fig. 10.)
b. Operated 100 feet from the truck by using the extension cables provided with the set.
c. Operated 200 feet from the truck by using two extension cables. (Under this condition, the power unit must be started and stopped at the trailer.)
d. Used as a source of power for lights, etc., at a distance of up to 200 feet from the trailer.
17
---- POWER
FRAME FM-62-A JNt
\ IMl B ' StT r ELgC- 5-GALLON 4 /GAS 0RuMS
^*7 l'l
A’lW ’ I X •
-’.‘’’r chest CH-II2-A ES t
\/\ tfia i
CORD GO-3I3-A «L I
vMld shz t ' CORD CO-XI6
z Ek */
„ . ' . ..XSl
Figure 10. Power Unit PE-95-( ), installed in Trailer K—52—( ).
14. Other Components
The following paragraphs describe the main chests in the radio set and important components other than the major components described above. The chests and additional components are:
Chest CH-120-A (par. 15)
Chest CH-121-A (par. 16)
Chest CH-89-A (par. 17)
Chest CH-119-A (par. 18)
Chest CH-88-A (par. 19)
Frequency Meter Set SCR-211 (par. 20)
Rectifier RA-63-(*) (par. 21)
Cordage (par. 22)
Remote control equipment (par. 23) Batteries (par. 24)
Crystals (par. 25)
15. Chest CH—120—A (Main Operating)
For field use (Radio Set SCR-499-A), Chest CH-120-A is mounted as shown in figure 11. In Radio Set SCR-399-A, the chest is mounted on a frame against the left (or road) side of Shel
ter HO-17-A and is held in place by a combination of cleats and turnbuckles. (See fig. 3.) All of the necessary radio components (table II) for one operating position are mounted in this chest. Junction Box JB-70-A and Speech Amplifier BC-614-E control transmission and change-over from transmission to reception. Radio Receiver BC-342-( ) and Loudspeaker LS-3 provide for reception. Box BX-19-A contains spare fuses, tubes, and lamps for the receiver. The lower half of the front cover of Chest CH-120-A swings down to form an operating desk large enough for a portable typewriter. Field legs (fig. 11) are strapped to this chest when it is to be set up away from the shelter. The total weight of the chest, including legs and full complement, is 292 pounds.
16. Chest CH-12 l-A (fig. 12)
The chest is mounted beside Chest CH-120-A in Shelter HO-17-A (fig. 3) and provides a second operating position. When removed from the shelter and set up in the field, Chest CH-121-A becomes a remote operating position from which the transmitter can be modulated over Telephone EE-8-( ), or keyed with Key J-45, through Junction Box JB-60-A (fig. 13). Chest CH-121-A contains Radio Receiver BC-312-( ), Loudspeaker LS-3, Box BX-19-A containing spare parts, and other accessories. A set of field legs is also supplied for this chest. The lower front cover of Chest CH-121-A opens to form a desk top. The total weight of the chest, including legs and full complement, is 157 pounds.
17. Chest CH-89-A
Chest CH-89-A is a combination parts compartment and seat bench. (See fig. 14.) In Shelter H0-17-A, the chest is parallel to the operating chest and fastened to the floor by means of wing bolts. (See fig. 3.) It is 6 feet 8 inches long, 141/2 inches high (not including cushions), and 18 inches wide. Fully packed, the chest weighs approximately 300 pounds. Its top is divided into four lids, which can be cushioned to serve as a seat for the operators. The compartment below each lid is subdivided for storage of spare parts, repair equipment, etc., as indicated on the chart attached to the chest. See table I for a typical list of the material packed in Chest CH-89-A. Two movable back rests, together with Straps ST-19-A hooked to Chest CH-89-
18
LAMP FIXTURE
SPEECH AMPLIFIER BC-6I4-E
JUNCTION BOX JB-70-A
COMPARTMENTS containing:
HEADSETS HS'3O CORDS CD-605 MICROPHONE T-5O MICROPHONE T-17
-BOX BX-I9-A
KEYJ-37
Figure 11. Chest CH-120-A with equipment installed—front view.
RADIO RECEIVER BC-342-( )
TELEPHONE
EE"8-( )
MICROPHONE
T-5O
LOUDSPEAKER
LS-3
COMPARTMENT FOR SPARE CORDS
UI5923,
A, secure the operator in place when driving on rough roads.
18. Chest CH-1 19-A (fig. 15)
In Shelter H0-17-A, Chest CH-119-A is placed along the right (curb) wall and is held in position by four, trunk clasps. (See fig. 3.) The chest is 55 inches long, 32% inches high, 12% inches deep and weighs approximately 287 pounds (loaded). Two sliding front panels permit access to the interior compartments in which are stowed the frequency meter, the portable typewriter, box of crystals, Cord CD-652, and tool equipment. Some additional storage space is available for other material. In Radio Set SCR-499-A, the compartment for Cord CD-652 is replaced by compartments for spare tubes, and Chest CH-119-A becomes Chest CH-119-B.
19. Chest CH-88-A (fig. 16)
The chest is mounted inside the shelter and on top of Chest CH-119-A. (See figs. 3 and 4.) It is held to the side of the shelter by four trunk clasps. It is 55 inches long, 18 inches high, and 12% inches deep; fully packed, it weighs approximately 165 pounds. Two sliding front panels permit access to the many compartments in which tuning units and other items are stowed.
20. Frequency Meter Set SCR-21 l-( )
The frequency meter set is carried in Chest CH-119-A where it is firmly held in place by a strap. (See fig. 15.) It serves as a frequency standard for the radio set, so that the operating frequency of the transmitter and the receivers may be determined accurately in the field. TM 11-300 is supplied with the meter and describes its operation in detail.
19
21. Rectifier RA-63-(*) (fig. 17)
Rectifier RA-63-(*) is a selenium type of battery charger which is used for charging the
12-volt battery in Chest CH-109-A. The rectifier also furnishes power to operate the keying and disabling relays when Chest CH-109-A is
RECEIVER ANTENNA (MAST SECTIONS MS-51,-52 AND-53)
CHEST
CH-I2I-A
|CHEST CH-I09-A
TLI5924:
LAMP
LOUDSPEAKER LS-3
B0X-8X-I9-A
TELEPHONE
EE-8-C )
RADIO RECEIVER BC-3I2-C )
Figure 12. Chests CH-121-A and CH-109-A, as used at a remote position.
JUNCTION BOX JB-60-A
CORD
CD-690 V
I STAKE 1 GP-8
20
removed to a remote position. The rectifier unit is fastened to the floor of the shelter, near the left wall and approximately midway between the two operating chests. (See fig. 3.)
Figure 13. Junction Box JB-60-A.
22. Cordage (fig. 155)
a. Cord CD-564 (power) is a 3-foot power cord connecting Radio Receiver BC-342-( ) with the a-c receptacle in the right side of Junction Box JB-70-A.
b. Cord CD-565 (control and power) is a 4-foot power and control cord connecting Radio Receiver BC-312-( ) with its receptacle in the junction box.
c. Cord CD-566 (control) is a 4-foot control cord connecting Radio Receiver BC-342-( ) with its receptacle in the right side of the junction box.
d. Cord CX-141/MRQ-2 (operating control) is 29 inches long and conducts control circuits between Junction Box JB-70-A and Speech Amplifier BC-614-E. The cord terminates in a plug receptacle on the panel of the speech amplifier and at a terminal strip in the junction box.
e. Cord CX-143/MRQ-2 (main audio) carries the audio output from Radio Receiver BC-342-( ) to switching circuits in Junction Box JB-70-A. This same cord also feeds Loud-
speaker LS-3 and Telephone EE-8-( ), both in Chest CH-120-A.
f. Cord CX-140/MRQ-2 (auxiliary audio) carries the audio current from Radio Receiver BC-312-( ) to Junction Box JB-70-A and also feeds Loudspeaker LS-3 in Chest CH-121-A.
g. Cord CD-763 (transmitter power) is 14 feet long. It connects Radio Transmitter BC-610-E with its a-c power receptacle in the junction box.
h. Cord CD-764 (transmitter control) is 15 feet in length. It carries speech and control connections from Speech Amplifier BC-614-E to Radio Transmitter BC-610-E and, in addition, furnishes Speech Amplifier BC-614-E with a-c power. The transmitter end of the cable plugs into the rear modulator apron of the transmitter ; the speech-amplifier end plugs into its front panel socket on Speech Amplifier BC-614-E.
i. Cord CO-335 (power and control) is 14 feet long and is used to carry power and control circuits between Junction Box JB-70-A and the shelter outlet to Power Unit PE-95-( ). In mobile operation, the plug end is connected to the bumper bracket underneath the rear of the truck. The cord passes through the hole in the shelter and then through the bottom of Chest CH-120-A. The plug on this end seats in the receptacle inside Junction Box JB-70-A.
j. Cord CD-652 (power and control) is a 100-foot cord for extending all connections between the shelter and trailer. It is equipped with a heavy-duty plug at each end for quick attachment to the system.
k. Cord CO-313 (a-c power) is a 100-foot cord for extending the a-c power connection of the power unit. One end of this cord is provided with a heavy-duty plug which fits the power plug at the tongue of the trailer. The other end of the cord has two lug type terminals from which a-c power can be taken for general use.
I. Cord CD-314 (a-c power) is a 3-foot cord for connecting any outside source of a-c power to Shelter H0-17-A for the operation of the radio set. The cord has a heavy-duty plug on one end for connection to the shelter, and a pair of lug type terminals for attachment to the source of power.
m. Cord CD-659 (12-volt battery cord) is 6 feet long and connects between the outlet receptacle on Junction Box JB-70-A and the plug outlet on Chest CH-109-A.
n. Cord CD-690 (power) is 6 feet long. It is used to connect Radio Receiver BC-312-( ) in
Th 1594 4
21
MAST BASE SPRING ASSEMBLY FOR MP-47
•TROUBLE
LAMP
CHEST CH-89-A
VACUUM TUBE VT-22O
OPERATING
SPARES
ELECTRIC DRILL
RECEIVING ANTENNA GUY ASSEMBLY
COUNTERPOISE
Figure 44. Chest CH.-89-A, parts compartments (open) and seat bench (closed)
OPERATING SPARES HARDWARE
ROLL OF SOLDER
MAST SECTIONS
[ MS-49,-50,-51,-52,-53,-54 STAKE ASSEMBLY GP-8 AXLE RL-27-A
22
Figure 15. Chest CH-119-A—front panels removed.
TUNING UNITS
COIL UNITS
CAPACITORS
’TLI5927I
—1
Figure 16. Chest CH-88-A—front panels removed.
" CORD CD-652
I®* \ EXTERNAL SPEAKING
FREQUENCY METER SET TUBE ' SCR-2II-( )
TYPEWRITER
ri-15926
TOOL BOX
BOX BX-34-B TE-48
.■ TU-47, ■ 48,-49-50 i 51-52-53,AND
54 .
1 MICROPHONE
BATTERIES
BA-30 AND BA-2
23
COIL UNITS
TUNING UNITS
BOX BX-34-B
TYPEWRITER
CHEST CH-88-A
CHEST
CH-II9-A,
TOOL BOX TE-48
REELS
DR-4
GHEST CH-I09-A
WIRE W-IIO-B
HEATER
CHEST CH-89-Aj
RECTIFIER
RA-63-( )
CORD CD-652
FRAME FM-59-A
•Tl1594b
Figure 17. Accessory components of Radio Sets SCR 399-A and SCR-499-A.
Chest CH-121-A to the storage battery m Chest CH-109-A, when both of these units are removed from the radio station.
o. Cord CO-316 (power and control) is a 6-conductor cord, 8.3 feet long. One end connects to the terminal board of the power unit; the other end connects to the power plug under the rear of the truck.
p. Cord CD-201-A is used to connect Key J-37 to Junction Box JB-70-A.
q. Cord CD-1117 is supplied with Loudspeaker LS-3.
23. Remote Control Equipment
a. When connected as directed in section IV, chapter 2, the remote control equipment provides for remote keying and voice modulation of Radio Transmitter BC-610-( ), reception with Radio Receiver BC-312-( ), and communication with the operator at the radio station. The remote operating position may be as much as 1 mile from the set. When receiving and transmitting from a remote position, switching of the remote telephone circuit from transmit
to receive must be accomplished at the radio set. Remote keying of c-w transmissions may be effected at the remote position; reception is then provided by using Radio Receiver BC-312-( ), Cord CD-690, and the 12-volt battery (in Chest CH-109-A) at the remote point. (See fig. 13.)
b. The equipment for remote control consists of—
(1) Two Telephones EE-8-( ), one in Chest CH-120-A and one in Chest CH-121-A.
(2) Junction Box JB-60-A, stowed in Chest CH-121-A.
(3) Key J-45, stowed in Chest CH-121-A.
(4) Two Reels DR-4, mounted in Frame FM-59-A. (See fig. 17.)
(5) Wire W-110-B, approximately % mile on each Reel DR-4.
(6) Axle RL-27-B, stowed in Chest CH-89-A.
24. Batteries
a. The 12-volt battery in Chest CH-109-A (figs. 2, 3, and 12) consists of two 6-volt storage batteries connected in series. They are in-
24
terchangeable with the batteries in Power Unit PE-95-( ). The battery output is obtained through a polarized socket mounted on Chest CH-109-A.
b. The batteries in Power Unit PE-95-( ) and those in Chest CH-109-A are exactly alike. In some installations, a switching arrangement is provided to permit the use of either set of batteries for operation of Radio Receiver BC-312-( ).
Figure 18. Carbon Microphone T-17.
Figure 19. Microphone T-50.
c. Dry-cell batteries are issued with various components and should be installed in accordance with the instructions in paragraph 35.
25. Crystals
Two sets of crystal holders (36 to the set) are provided in Box BX-34-B (fig. 15), so that the transmitter may be operated at any of the frequencies listed in table V.
Figure 20. Headset HS-30-( ).
Figure 21. Key J-37.
' TU5627 *
25
Section II. INSTALLATION
26. Siting
Note. The following siting information for Radio Set SCR-499-A is also applicable to Radio Set SCR-399-A as a fixed station.
Radio Set SCR-499-A should be set up on a hilltop, elevated ground, or on terrain which is flat over a wide area. A valley or other low ground is to be avoided as much as possible, since the surrounding higher terrain absorbs r-f energy and limits the operating range of the set. Particular care should be taken to avoid a site under or close to steel bridges, underpasses, power lines, and power units, because of the extremely short range possible from any of these sites. If the doublet antenna is used, its directional characteristics should be considered, as explained in paragraph 129.
27. Uncrating, Unpacking, and Checking Radio Set SCR-399-A
a. A shipment of Radio Set SRC-399-A consists of two boxes. One contains Shelter HO-17-A with operating components installed, weighs 7,255 pounds, and is 13'-3" long, 7'-8" wide, and 6'-8" high. The second contains Trailer K-52-( ) with Power Unit PE-95-( ) installed, weighs 4,900 pounds, and is 9'-2" long, 6'-5" wide, and 6'-6" high. Two packing lists are shipped with each box, one attached to the outside and one inside the box. For greatest convenience, the radio set should be uncrated and unpacked as near the operating site as possible. Do not open any box until ready to use its contents.
b. The recommended procedure for uncrating, unpacking, and checking Radio Set SCR-399-A is as follows:
(1) Use nail pullers and pry bars to remove the top of the box containing Shelter H0-17-A. The top must always be removed first, so that the sides are free for the next step.
(2) Attach one end of a steel cable or strong rope to the rear of a truck. Fasten a hook to the other end of the cable and catch this hook over the top edge of one side of the shelter box. Use the truck to pull this side from the crate.
(3) Repeat step (2) to remove the other side and the ends of the box. (If a truck is not available, use nail pullers and crowbars.)
(4) Carefully remove the waterproof wrappings from about the shelter.
(5) The openings (windows, doors, etc.) in
the shelter are covered with adhesive tape over which a sealing compound has been placed. (See fig. 22.) To remove this protective material, loosen a small section with a sharp object such as a screwdriver or chisel. Grasp the adhesive tape and pull it away from the shelter. The compound will come off with the tape.
(6) Remove the four corner bolts to free the shelter from the crate platform. (See fig. 23.)
Figure 22. Shelter HO-17-A, sealing compound in place.
(7) Enter the shelter and carefully remove the shoring (wooden props) and bags of silica gel.
(8) Remove the straps which hold the separately packaged components (antenna tuning unit, masts, etc.), in position on the floor of the shelter.
(9) Check the contents of each box against the packing list.
(10) Open each chest and check its contents against the chart on the chest. Refer to table I and to the chest lay-out diagram. (See figs. 137 through 145.)
Table I. Chests and contents
Note. This tabulation is general; an itemized list of contents accompanies each chest. See figures 137 through 145 for lay-out and dimensional drawings of the chests.
CHEST CH-88-A (fig. 138)
24 Tuning units
14 Coil units
1 Microphone T-50
3 Capacitors
*1 Carton spare fuses Spare pilot lamps
* Complete list of contents in carton
26
CHEST CH-89-A (fig. 140)
*8 Cartons operating spares
*2 Cartons hardware
1 Analyzer
1 Hydrometer Antenna assembly
Tools
Cords
1 Trouble lamp
Spare lamp bulbs
Spare tubes
3 Straps ST-19
1 Roll solder
1 Anticorona ball
Machine oil
Carbon tetrachloride
CHEST CH-109 (fig. 141)
2 Storage batteries
CHEST CH-112 (fig. 145)
1 Cord CD-659, operating
1 Cord CO-335, operating
1 Cord CO-652, spare
1 Cord CO-313, spare
CHEST CH-119 (fig. 143)
1 Box BX-34-B, complete with 72 crystals
1 Typewriter
2 Trouble lamps, 110-volt
1 Frequency Meter Set SCR-211
1 Tool Box TE-48
Miscellaneous tubes
CHEST CH-120-A (fig. 146)
Junction Box JB-70-A
Speech Amplifier BC-614-E
Radio Receiver BC-342-( )
Loudspeaker LS-3
Lamp fixture
Headsets HS-30-( )
Microphone T-50-( )
Key J-37
Field Telephone EE-8-( )
Box BX-19-A, containing spare fuses, tubes, and lamps for receivers
CHEST CH-121-A (fig. 147)
Radio Receiver BC-312-( )
Loudspeaker LS-3
Headsets HS-30-( )
Spare battery cord
Field Telephone EE-8-( )
Lamp fixture
Box BX-19-A
Key J-37
* Complete list of contents in carton
(11) The second box (fig. 24) contains Trailer K-52-( ) in which Power Unit PE-95- ( ) is installed prior to shipment. With nail pullers and prybars, remove the top of this box.
(12) Remove the four sides of the trailer box.
(13) Remove the waterproof wrapping from about the trailer.
(14) Remove the shoring and straps which hold the trailer to the bottom of the box. (See fig. 25.)
(15) Remove the trailer from the bottom of the box.
(16) Check the contents of the' trailer against the packing list.
28. Uncrating, Unpacking, and Checking Radio Set SCR-499-A
a. A shelter and trailer are not supplied with Radio Set SCR-499-A. Its components are shipped in 23 boxes. (See table II.) Two packing lists are shipped with each box; one inside
CORNER BOLT
:holo down ASSEMBLY
-LIFTING-_____J
'STRAPS S123 .0
Figure 23. Shelter HO-17-A on shipping crate platform.
£ SEALING
*" COMPOUND f-'
27
Figure 24. Shipping Box for Trailer K-52-( ) with Power Unit PE—95—( ) installed.
the box and one outside. Do not open any box until its contents are needed for immediate use. For example, if Radio Set SCR-499-A is to be operated on local commercial power, do not open box No. 17 which contains six gasoline cans.
b. The following procedure for uncrating, unpacking, and checking Radio Set SCR-499-A is recommended.
(1) Use nail-pullers and prybars to open each crate.
(2) Remove the outer wrappings and bags of silica gel.
(3) Check the contents of each box against the packing list.
Figure 25. Trailer K—52—( ~) with Power Unit PE-95-( ) installed, on shipping crate.
28
Table II. Typical packing list for radio set SCR-f99-A
No. of boxes: 23 Dimensions Shipping weights Weight of various items (lb)2
Contents Length (inches) Width (inches) Height (inches) Cubic feet Gross (lb) Net (lb)
BOX NO. 1 1 Transmitter BC-610-E 1 Cord CD-763 1 Cord CD-764 38 32% 34 21% 47, 39% 35.1 755 497 452
BOX NO. 2 1 Chest CH-120-A1 59 50 y2 25 16% 35 23% 30.2 560 292 286
BOX NO. 3 1 Chest CH-121-A1 39 31 23 16% 30 23% 15.5 340 162 155
BOX NO. 4 1 Antenna Tuning Unit BC-939-A 31 23% 16 11% 21 15% 6 125 48 48
BOX NO. 5 1 Chest CH-89-A1 85 80 23 18% 19 141%, 21.4 492 330 300
BOX NO. 6 1 Chest CH-109-A with: 2 6-volt batteries 31 25% 12 9% 14 11% 3 140 101 101
BOX NO. 7 1 Chest CH-112-B with: Cords CO-335, CD-659, CD-652, CO-313 49 431% 18 13% 23 18% 11.7 292 196 196
BOX NO. 8 1 Mast Base Bracket MP-59-A 1 Antenna plate 10 Fastener assemblies Linoleum 1 Base heater mounting 1 Base rectifier mounting 1 Strap 1 Ground lead assembly Copper rope 1 Concentric lead Miscellaneous hardware 21 19 16 3.7 74 34
BOX NO. 9 1 Fire extinguisher 1 Holder, for extinguisher 3 Seat bench backs 40 13%s 18 4%4 8 18% 3.3 86 28 17%
BOX NO. 10 2 Mast Base Brackets MP-50-A 1 Mast Base MP-47-A 2 Mast Base MP-48 (assembled) 27 ■ 15 12 2.8 89 57
BOX NO. 11 1 Electric heater 1 Rectifier RA-63-(*) 31 12% 13% 18 11 % 9% 17 12 7% 5.4 111 42 17% 29%
BOX NO. 12 1 Frame FM-59 1 Bumper clamp 24 20 17 4.4 75 31 (see box No. 16, Reels DR-4).
BOX NO. 13 7 Seat bench cushions 6 Covers (chest and transmitter) 33 25 25 11.8 153 75
BOX NO. 14 1 Chest CH-88-A1 63 58 26 12% 19 19% 17.5 343 175 165
BOX NO. 15 1 Chest CH-119-B 63 57 19 12% 40 321% 27.3 453 236 287
BOX NO. 16 2 Reels DR-4 (with wire) 26 17 24 6 229 165 190
1 See table I for list of equipment installed in chest.
2 Approximate weight of item when set up for use:
3 Length of nozzle attachment,
4 Diameter of tank.
29
Table II. Typical packing list for radio set SCR-499-A (contd)
No. of boxes: 23 Dimensions Shipping weights Weight of
Contents Length (inches) Width (inches) Height (inches) Cubic feet Gross (lb) Net (lb) items (lb)2
BOX NO. 17 6 Gasoline cans (5 gal) 31 22 21 7.8 120 60
BOX NO. 18 7 Mast Sections MS-44-A 1 Canvas Cover BG-176 70% (Packe (1 . io% in Roll 6% BG-176) 2.6 75 47 47
BOX NO. 19 7 Mast Sections MS-44-A 1 Canvas Cover BG-176 70% (Packe d . io% in Roll 6% BG-176) 2.6 75 47 47
BOX NO. 20 7 Mast Sections MS-44-A 1 Canvas Cover BG-176 70% (Packe d . io% in Roll '63% BG-176) 2.6 75 47 47
BOX NO. 21 1 Power Unit PE-95-( 3 Gas can spouts 1 Cord CO-316 1 Set running spares 2 6-volt batteries ) 80 67%. 35 28% 48 38% 78 2190 1600 1556
BOX NO. 22 1 Canvas Cover BG-1 3 Guy GY-24-A 12 Insulators IN-82-A 18 Stakes GP-2 3 Mast Base MP-19 9 Guy Plate MP-20 6 Guy GY-22-A 02-A 20% (Packe d 18% in Bag 13% BG-102 2.7 -( )) 97 73 23
BOX NO. 23 1 Cord CD-1290 Wire W-28, 250 ft 2 Reel RL-29 12 Guy GY-41 1 Steel tape, 100-ft 2 Instruction sheets for doublet antenna kit 1 Bag BG-102-( ) 20% (Packe d 18% in Bag 13% BG-102 2.7 -( )) 55 31 31
2 Approximate weight of item when set up for use.
29. Installation of Radio Set SCR-399-A
a. Mobile Installation. If Radio Set SCR-399-A is to be used as a mobile station, Shelter H0-17-A should be installed on a 21/2-ton, 6x6, cargo truck. (See fig. 1.) The following procedure for setting up the radio set for mobile use is recommended:
(1) Remove the canvas cover, roof bows, and side framing from the truck; drop the tail gate.
(2) With all equipment installed, the shelter weighs about 214 tons. If a suitable hoist, is available, lift Shelter iH0-17-A by its four lifting straps (fig. 23) and place it on the truck body so that the entrance door is toward the rear. If no hoist is available, some other method must be devised for raising the shelter to truck level and sliding it on to the truck. This work is easier if the heavy items of radio equipment are first removed from the shelter, as explained in paragraphs 189 and 190.
(3) Attach the hold-down clamps (two on
each side of the shelter) to the truck body sides to hold the shelter firmly in place. If the cargo truck has a wooden body, bolt on the four clamp anchors. (See Parts List for Shelter HO-17-A.)
(4) Place Antenna Tuning Unit BC-939-A on top of the transmitter and fasten it in position.
(5) Bolt Mast Base Brackets MP-50-A with Mast Bases MP-48 to the rear of the shelter. (See fig. 26.) Attach the short external lead wire between the mast bases and the lead-in bushings. Bolt Mast Base MP-47-A in place on the roof of the shelter and attach the antenna lead wire between the binding post on the mast base and the binding post at the rear of Antenna Tuning Unit BC-939-A. For information on assembling the antennas, see paragraph 33.
(6) Attach the bumper bracket for Cord CO-335 to the left-hand bumper at the rear of the truck. Do not drill holes in the truck. If the truck body is wooden, chip a small amount of
30
‘ .TRANSMITTER ANTENNA
.. MAST SECTIONS
I MS-49-50,-51,-52,-53 f TRA.LER K-52-()
RECEIVING ANTENNA I W|TH P0WER UNiT .
f MAST SECTIONS____ / PE-95'( )
MS-51,-52,-53 *"/
। MAST BASE MP-47-A * I
/, MAST BASE I MAST BASE
/ I ./MP-48
BRACKET MP-50-A .
r : B' ____________________ P »
• t , .<■ - .-■■ *^8898
w -■ ___—.—.i ,•< ., tvsSsBs-'
" ; ' • : » *. ■
■ I J ' ’
' .'I ! .... I .. BV ' Vjl ''»
f® j I • ’ SB 1 1
li r /IL^<
f IT ! ’ V WML--
fK?y . ■
;'T .*A- I . - . JiLAi ’ W
I . c x |
I -r-- "
/ f I Ly/'
/ / I I
. SHELTER HO-I7-A&... / FAIRLEADS '• . .
/ I
I ' CORD BUMPER CORD ■•
\ uo-3351 \ clamp-
Figure 26. Shelter H0-17-A and Trailer K-52-( ), whip antennas, Cord CO-335, and Cord CO-316 installed.
wood from the floor beam which extends over the bumper. (See fig. 27.)
(7) Extend Cord CO-335 through the hole and clamp in the rear of the shelter. Bring the outer plug down behind the truck body and clamp it into the bumper bracket. (See figs. 26 and 27.)
(8) Attach the flexible section of the speaking tube to the fitting at the front of the shelter, and route the speaking tube into the left-hand truck window. (See fig. 28.) Hook the speaking tube mouthpiece inside the truck cab where it will be convenient to the driver.
(9) Attach one end of the ground strap to the terminal at the front of the shelter. If the truck has a metal body, bolt the other end of the ground strap to the nearest available point. If the truck has a wooden body, run the ground strap to the nearest point on the metal chassis and clamp it securely. (See fig. 28.) Connect an
additional ground strap between the stud at the rear of the shelter and the steel frame of the truck.
(10) Couple the trailer to the rear of the truck and plug Cord CO-316 into the receptacle clamped in the bumper bracket.
b. Fixed Installation. If the shelter and trailer are to be used in a fixed location, the truck will not be necessary and may be released for other uses. In this case, the procedure for installation is as follows:
(1) If possible, select a site for the shelter in accordance with the instructions given in paragraph 26. Raise the shelter above the ground and block it in position.
(2) Place the trailer in any convenient position near the shelter. By proper use of the extension cords (par. 56), the trailer may be placed at a distance of up to 200 feet from the shelter.
31
le
le
ie le
id he ed 'or
in
rand
isi-
JX* be the
Figure 27. Bumper bracket attached to rear of truck.
Figure 28. Speaking tube and ground lead from Shelter FIO-17-A to truck.
(3) See FM 5-20 and apply camouflage to the shelter and trailer as required.
(4) Follow the instructions given in a (4) and (5) above.
(5) Connect Counterpoise CP-15-B to the ground binding post at the front of the shelter. Lay the counterpoise on the ground and fan out the individual conductors.
(6) Bring Cord CO-335 out through the clamp in the rear of the shelter.
(7) Connect Cord CO-316 to Cord CO-335 directly, or through extension cords.
30. Installation of Radio Set SCR-499-A
a. General. (1) If possible, provide protection from the weather by setting up the equipment in a tent or shed. If Radio Set SCR-499-A is set up in the open, every precaution should be taken to protect the transmitter from rain and dirt. The major components are provided with canvas covers which should be used to protect them from the weather.
(2) Components supplied with Radio Set SCR-499-A are listed in paragraph 5. Use figure 2 as a guide in placing the various components, so that the interconnecting cords will reach from one to the other as required.
b. Transmitter. Set up the transmitter with the antenna tuner fastened in place as shown in figure 5. If the installation is made on bare ground, raise the transmitter above the ground and block it on wooden skids or planks to keep the base dry.
c. Transmitting Antennas. (1) Long wire antenna. If a long wire antenna is used, choose the best length for the operating frequency. (See table IV.) Insert an antenna insulator between the outer end of the wire and the rope used to anchor it to a tree or other convenient support. Keep the antenna as high and free of surrounding objects as possible. Attach a lead-in to the antenna binding post on Antenna Tuning Unit BC-939-A.
(2) Whip antenna. Mount Mast Base Bracket MP-59-A on the rear of the transmitter by hooking it to the bolts which hold the antenna tuning unit in place. Mount Mast Base MP-47-A in the mast bracket and insert the five-section whip antenna consisting of one each Mast Sections MS-49 to MS-53, inclusive. For detailed instructions on assembling the transmitting whip antenna, see paragraph 33.
(3) Doublet antenna. For information on the
EXTERNAL
SPEAKING TUBE
» GWiJ’lO LEU®
j^RQUND CLAMP
32
installation and use of the doublet antenna, see section II, chapter 4.
d. Other Operating Components. (1) Set up the following components as shown in figure 2:
(a) Chest CH-120-A, CH-121-A, and CH-109-A.
(fi) Rectifier RA-63-(*).
(c) Electric heater and blower, if necessary.
(2) Choose a suitable point within reach of the power extension cords provided with the set, and set up Power Unit PE-95-( ) in accordance with the instructions in TM 11-904.
(3) Set the accessory components (Chests CH-89-A, CH-119-B, and CH-88-A) out of the way until the connections and interconnections have been made (par. 32) ; then place these components convenient to the operating positions, as shown in figure 2.
31. Connections and Interconnections of Radio Set SCR-399-A
When shipped, the operating components of Radio Set SCR-399-A are completely installed, mounted, and interconnected. (See figs. 3 and 4.) Make a general inspection of the equipment and check with the cording diagram (fig. 155) to see that:
a. Power Unit PE-95-( ) is properly connected, both mechanically and electrically, to Shelter H0-17-A.
b. Receiver, speech-amplifier, and transmitter cords are properly plugged into their respective sockets.
c. All wingnuts, wing head bolts, turnbuckles, etc., are tight.
32. Connections and Interconnections of Radio Set SCR-499-A
a. After the components of Radio Set SCR-
’ —........................ \
■*---
Jr ■' « I 1
/ \
« ■ / flmX- 1
......f -JI . H
• W sozoo -w .-IT- \
LAMP ■ ■ Z1 LAMP (ROOF) - '' /
' 'a 7 / -
! oTkffl -> X, LX •= ■ ?
j TO LAMP ' Xi TO RADIO TRANSMITTER BC~6lO~EFj
INCHEST. .
CH-I2I-A ■ To SMBE .^^^LOwtR (JMIWPjrZgr : 7- I I
i \ I f 0 ‘ / ■ si
J . /X ij&sc I
\ so^ ' Z- E%q ■ ■ B g'
// ' X—S°eo’ a ^B CC
r Wr? W z | r di
TO CHEST . . - . *** B
I ' LX \ ..1J S°20S CORD 00-565 TO 00-5)2 RECTIFIER •’ ' H V
W
-- \ .kJL B\ TO HEATER
.Xx ' M| * |l\ in
AUO.O BC-512 W f»®SHELTER * *
... .W soeo< ......
'^ \ /jfTO FfADIO RECEIVERS B IT ZV
■ \ jff BC-3I2-I ) . : K | , nil
■ / TO VENTILATOR ’ B • . I ] X® I ’ ’ do
/ BLOWER IN jf X. ' t-1 ISLzc'., ® ■ 14 \
SHELTER IF \ . |;f TO RECTIFIER |g tg Z ' I
i. TO SPEAKER 2ND AUDIO JA-3K - RA‘63'< 1 ■ • If
z | g ON RADIO RECEIVER 8C-3l2-( ) / 'ME P ‘ /
,?;M^ -Xi. h -.a. . • tm . .'\ / . H ■ BAn -TLi5932
’ an
TO POWER
UNIT PE-95R )
Figure 29. Cord connections through bottom of Chest CH-120-A to bottom of Junction Box JB-70-A.
33
499-A have been placed in their operating positions, use the cording diagram (fig. 155) and the bottom view of Chest CH-120-A (fig. 29) as guides for connecting:
(1) Cord CD-763 from the transmitter to Junction Box JB-70-A.
(2) Cord CD-764 from the transmitter to Speech Amplifier BC-614-E.
(3) Cord CD-659 from Chest CH-109-A to Junction Box JB-70-A.
(4) Cord CD-565 from Radio Receiver BC-312-( ) to Junction Box JB-70-A.
(5) Cord from Rectifier RA-63-(*) to Junction Box JB-70-A.
(6) Cords from the blower and the heater to Junction Box JB-70-A, if these two items are needed.
(7) Cord CD-564 from Radio Receiver BC-342-( ) to the Junction Box JB-70-A.
(8) Cord CD-566 from Radio Receiver BC-342-( ) to the Junction Box JB-70-A.
(9) Cord CX-140/MRQ-2 (auxiliary audio) from Chest CH-121-A to Junction Box JB-70-A.
(10) Cord CX-141/MRQ-2 from Junction Box JB-70-A to Speech Amplifier BC-614-E.
(11) Cord CX-143/MRQ-2 from Radio Receiver BC-342-( ) to Junction Box JB-70-A.
(12) All key, loudspeaker, and lamp cords, as required.
(13) Cord CO-335 to Junction Box JB-70-A.
(14) Cord CO-316 from Power Unit PE-95-( ) to Cord CO-335, directly or through extension cords, as required.
b. Connect Counterpoise CP-15-B to the ground binding post of the transmitter. Lay the counterpoise on the ground and fan out the individual conductors.
33. Installation of Antennas on
Radio Set SCR-399-A
a. Select the following items from Chest CH-89-A. (1) One Mast Section MS-49.
(2) One Mast Section MS-50.
(3) One Mast Section MS-51, to which a metal S-link has been attached (for guying down the transmitter antenna).
(4) Two Mast Sections MS-51.
(5) Three Mast Sections MS-52.
(6) Three Mast Sections MS-53.
(7) Insulated guy ropes for the transmitting antennas.
(8) Two insulated guy ropes for the receiving antennas.
b. Assemble the transmitting antenna (fig. 26) as follows:
(1) Screw Mast Section MS-49 into Mast Section MS-50. Use two pairs of gas pliers to tighten the connection. Tape the joint with 1^-inch friction tape.
(2) Repeat this procedure with Mast Sections MS-51, MS-52, and MS-53.
Note. Any mast section with a lower number is above that with a higher number.
(3) Carry the guy rope and the assembled antenna sections onto the shelter roof, and screw Mast Section MS-53 into Mast Base MP-47-A.
(4) Attach the catches at the rope end of each guy rope to the holes in the corners of Mast Base Brackets MP-50-A.
(5) With hand outstretched at shoulder height, stand at the center of the roof and bend the antenna backwards to a horizontal position.
(6) Hold the antenna down in this position, walk to the rear of the roof, and with the other hand pick up the insulator end of the guy rope and attach it to the S-link on Mast Section MS-51.
c. Assemble the left-hand receiving antenna (fig. 26) as follows:
(1) Screw Mast Section MS-51 into MS-52. Use two pairs of gas pliers to make the connection tight. Tape the joint with 1/2-inch friction tape.
(2) Screw Mast Section MS-53 into Mast Section MS-52.
(3) Screw Mast Section MS-53 into Mast Base MP-48 on the left rear corner of the shelter.
d. Assemble the right-hand receiving antenna by.repeating steps c(l) and (2) above. Screw the assembled sections into Mast Base MP-48 on the upper right rear corner of the shelter.
e. Attach guy rope insulators to the receiving antennas. Tie the guy ropes to the rear corners of the truck or shelter.
f. Use these two guy ropes to pull the receiving antennas down when driving in a city or under low obstacles. (See fig. 1.) However, better reception will result with receiving antennas in the vertical position.
g. For information on the use of the doublet antenna, see section II, chapter 4.
34
34. Installation of Antennas on
Radio Set SCR-499-A
a. Assembly and installation of the whip antennas for Radio Set SCR-499-A is the same as for Radio Set SCR-399-A (par. 33), but with the following exceptions:
(1) Mount the assembled transmitting antenna in Mast Base Bracket MP-59-A, which is hooked to the transmitter.
(2) Put the two assembled receiving antennas into their respective antenna receptacles on Chests CH-120-A and CH-121-A. (See fig. 2.)
(3) Use the antennas in their vertical positions.
b. For information on the use of the doublet antenna, see section II, chapter 4.
35. Installation of Dry Batteries
a. Telephones EE-8-( ), Frequency Meter SCR-211-( ), and Analyzer BC-1052-E require dry batteries as listed below:
Component
Telephone EE-8-( )
Frequency Meter Set SCR-211-( )
Analyzer BC-1052-E
b. To install or replace dry batteries, carefully follow the instructions in the technical manual or instruction sheet issued with each component.
36. Placing Storage Batteries in Service
Caution: If electrolyte spills on skin or clothing, wash off immediately with cold water. Apply bicarbonate of soda or ammonia to the affected parts, if available.
a. Instructions. Examine the storage batteries for Chest CH-109-A and Power Unit PE-95-( ). A card attached to each battery gives the manufacturer’s instructions for preparing that battery for service. READ THE MANUFACTURER’S INSTRUCTIONS AND FOLLOW THEM CAREFULLY.
b. Example. The following is an example of the information which appears on a manufacturer’s instruction card:
(1) This battery is of the dry-charged type.
(2) The electrolyte to be used is diluted sulphuric acid having a specific gravity of 1.256 at 80° F. It is packed in a separate container. In tropical climates, use electrolyte having a specific gravity of 1.200, produced by mixing 10
parts of the 1.265 electrolyte with 3 parts of water. Be sure to use distilled water, or other water known to be suitable for use in a lead-acid storage battery.
Caution: Never add the water to the acid.
(3) Remove the vent caps. Remove and destroy the scotch tape which covers the vent holes. Fill each cell with the correct electrolyte to a level % inch above the tops of the separators. Replace the vent caps and tighten securely.
Caution: Do not put cold electrolyte into a warm battery, or warm electrolyte into a cold battery. Severe damage will result.
(4) If the battery is filled with 1.200 electrolyte for tropical use, stamp the numeral 1 on the lead top connector at the positive cell, for the information of anyone servicing the battery in the future.
(5) Before placing the battery in service, allow it to stand from 4 to 12 hours after filling.
Note. In an emergency, the battery may be placed in service 1 hour after it has been filled with the proper electrolyte. This is not good practice.
Batteries
2 BA-30
6 BA-2
4 BA-23
1 No. 2 dry cell
____________2 BA-34 (7i/2-volt, “C”)
(6) If possible, give the battery a freshening charge at 6.0 amperes for 16 to 20 hours before placing it in service. It will give satisfactory results without this charge if the battery temperature is above 50° F. If the battery temperature is below 50° F., it must be given a freshening charge.
37. Repacking
a. The components of Radio Set SCR-499-A can be quickly disconnected to dismantle the station into a number of relatively small items for transport by aircraft or other suitable conveyance.
b. The circumstances of field transportation differ widely and, therefore, no definite repacking procedure can be given. The following procedure is recommended as a guide for preparing Radio Set SCR-499-A for field transportation.
(1) Set the accessory Chests CH-119-B, CH-89-A, and CH-88-A where they can be repacked conveniently as their original contents are removed from the set.
(2) Remove the seat cushions and backs
35
from Chest CH-89-A and tie them into a secure and compact bundle.
(3) Disconnect the set cording, keys, lamps, and other small components from the set.
(4) Pack each of these items in the accessory or operating chests as indicated in the contents chart of each chest.
(5) Remove and disassemble the transmitting and receiving antennas.
(6) Pack the antenna mast sections in Chest CH-119-B.
(7) If possible, place protective wrappings about the heater, fire extinguisher, Rectifier RA-63-(*), and other components for which
there is no space in the chests. These items are usually handled separately. (See fig. 17.)
(8) Before - closing and locking the chests, stuff any available filler into compartments that require such material to prevent damage to their contents.
(9) Cover the components for which canvas covers are provided.
(10) Repack the doublet antenna components in their original shipping bags.
(11) Carefully store and secure the repacked components in the conveyance being used for transporting the equipment.
Note. For emergency field transportation, Radio Set SCR-399-A can be removed from Shelter HO-17-A. (See pars. 189 and 190.)
CHAPteR 2
TL 17321
CHAPTER 2
OPERATING INSTRUCTIONS
Note. For information on destroying the equipment to prevent enemy use, see destruction notice at front of manual.
Section I. CONTROLS AND THEIR USE
38. General
The controls of Radio Sets SCR-399-A and SCR-499-A are described in this section. A series of line drawings, keyed to the text, are used to illustrate the controls and to show their location on the equipment.
an approximate setting for the PLATE TUNING wheel.
b. PLATE TUNING wheel controls the tuning of the p-a (power-amplifier) tank circuit. Its position is registered on the PLATE TUNING dial directly above. The lock holds the PLATE TUNING wheel securely in position.
c. P. A. PLATE meter measures the current in the p-a plate circuit, thus indicating correct tuning of the p-a stage.
4 @ g
4
To o /
/ ©@
4^ ©©© \
TLI6507
o. MODULATOR BIAS control adjusts the This switch has two positions, ON and OFF. bias iectihei and, therefore, of
In the ON position, plate power is applied to all e m° u a or u es-
tubes in the transmitter which had not been I _ —i
previously turned on by the FILAMENT 11 --- ,; 11 ij 1 \
POWER switch. A red pilot lamp above this T &MP-
switch lights when plate power is applied. • I i ) B o L—-■
Caution: The receiver disabling circuits are
inoperable with this switch in the ON position;
do not key the set under this condition.
n. FILAMENT VOLTAGE control adjusts
the filament voltage of all tubes in the trans- • • •
mitter except the bias rectifier and the drivers. 4 ~ "jX q 11
The circuits are so arranged that a FIL. VOLT- ,*fPSVr
[plate ------------------
T---------—WEf? sw'*ch \ I-1 /
I LJ lj ~~i4f l«J / A r? swUchj
/ \ <(Q)> / -----------------
' , © ©) . -XZ ,-i
[____________/ {(□) . fp' r yZa>
^\/tlI6506 TLI6508
40
p. FUSES FSn FS2, FS3, FS4, and FS5 are located on the front panel of the transmitter. FUSES FSX and FS2 are line fuses. FUSE FS3 is in the primary of transformer T6. FUSE FS4 protects transformers T2, T3, T4, and T5; relays RYn RY2, RY3, and RY4; and lamp LM3. FUSE FS5 protects transformer Tx and the primary of the speech-amplifier power supply.
40. Tuning Unit Controls
a. The crystal jack is a two-pin receptacle to accommodate a Crystal Holder FT-171-B containing a crystal within the frequency range of the tuning unit.
b. M.O.-XTAL switch is thrown to the M.O. position for m-o (master-oscillator) operation and to the XTAL position for crystal-controlled operation.
c. M.O. control determines the frequency of the master oscillator. Calibrations on the dial of this control permit it to be set to any frequency within its range through reference to the tuning chart.
d. DOUB control is used to tune the bufferdoubler tank circuit to resonance with the sig-
I--------------------
nal from the oscillator. An approximate setting for this control can be obtained from the tuning charts.
e. 1NT AMP control is used to tune the i-p-a tank circuit to resonance with the signal from the buffer-doubler. An approximate setting for this control is also found on the tuning charts.
41. Antenna tuning Unit Controls
a. COUPLING INCREASE control is an antenna-coupling adjustment knob. The setting of this knob is determined from the tuning charts and is read on counters directly above the knob.
b. FREQUENCY 18MC-INCREASE-10MC control is the high-frequency tuning adjustment for the antenna. It is set approximately by the tuning charts and is read on counters directly above the control.
ED | O
-----^eter ) (
Antenna X CC3 J range switch /C
-------tt-tZJ
c. FREQUENCY 10MC-INCREASE-2MC control is the low-frequency tuning adjustment for the antenna. It is set approximately by the tuning charts and is read on counters directly above the control.
d. ANTENNA CURRENT meter, in series with the antenna coupling control, measures the r-f current in the antenna circuit.
e. Antenna range switch is marked 2-10MC LONG WIRE 10-18MC. In the 2-10MC position this switch matches the whip antenna to the low-frequency range of the transmitter. In the LONG WIRE position the antnena is so arranged that the transmitter will work on any frequency within its range into a long-wire antenna. In the 10-18MC position the switch matches the whip antenna to the high-frequency range of the transmitter.
TL165II
TLI65IO
41
r RECEIVER \ DI SABLIN G I
© © \
A/—J \
© SWp>
TLI65I2
42. Junction Box JB-70-A Controls
a. REMOTE TELEPHONE terminals are for the connection of up to a mile of Wire W-110-B from remote Telephone EE-8-( ) or from remote Key J-45.
b. BC-312 RECEIVER DISABLING switch has two positions, marked ON and OFF. With this switch in the ON position, Radio Receiver BC-312-( ) SEND-RECEIVE switch in the SEND position, and the transmitter carrier on, disabling occurs as follows: The disabling short-circuits the receiver input connections to protect the antenna coils, and also short-circuits the loudspeakers to prevent acoustic feedback to the dynamic microphone. In the OFF position no power is applied to the antenna-disabling relay in the receiver, and the loudspeakers are not short-circuited; therefore, the receiver is operative at all times.
c. BC-342 RECEIVER DISABLING switch functions for Radio Receiver BC-342-( ) in the manner described above for Radio Receiver BC-312-( ).
I' /
© © X
TLI65I3 ^^*** 0 8 SZXT
( © ©0)© ©©© (gj <
I___1 —____I T L16 Si 6
TRANS. OFF position, no keying or modulation of the transmitter may occur (except in emergencies when the transmitter PLATE POWER switch is turned ON). In the REC. TO EE-8 position (with the REMOTE CONTROL EE-8 switch other than NORMAL), the remote location can hear the signals being received in the shelter.
i. START-STOP buttons are remote controls for Power Unit PE-95-( ). Pressure on the START button applies current to the starting
k. C.W. SIDETONE switch has three positions, marked TO BC-312, OFF, and TO BC-342. In the TO BC-312 position, sidetone from the transmitter is applied to the HEADSETS jacks on the left side of Junction Box JB-70-A panel and to the loudspeaker in Chest CH-21-A. In the OFF position, no sidetone is applied. In the TO BC-342 position, sidetone from the transmitter is applied to the HEADSETS jacks on the right side of Junction Box JB-70-A panel and to the loudspeaker in Chest CH-120-A. The same sidetone is applied to the remote telephone line in either TELEGRAPH position of REMOTE CONTROL EE-8 switch.
I. RECEIVER OUTPUT switch in the normal position connects the left HEADSETS jacks to Radio Receiver BC-312-( ) and the right HEADSETS jacks to Radio Receiver BC-342-( ). In the TRANSPOSED position the left HEADSETS jacks are connected to Radio Receiver BC-342-( ) and the right HEADSETS jacks are connected to Radio Receiver BC-312-( ).
43. Speech Amplifier BC—614—E Controls
a. CARBON MIC. 1 is the panel marking for a gain control and jack for Microphone T-17 or T-30. When using Microphone T-17 or T-30, plug it into the CARBON MIC. 1 jack and adjust the corresponding gain control as described in paragraph 51.
43
Xx
XX XU------f=t\
X&X©© Q \
*r©@ /
(g © I
TLIS5I8
MENT POWER switch is in the ON position.
e. An auxiliary KEY jack on the speechamplifier panel makes it possible to key the transmitter in emergencies.
Caution: The receiver disabling circuits are inoperative when this key jack is used. To avoid burning out the receiver input circuits, turn off the receivers during transmission from this key jack, or make sure that they are tuned to a frequency considerably different from the transmitted frequency but not to an harmonic of the transmitted frequency.
f. The eight-pin receptacle marked TO BC-610 is used to connect Cord CD-764 to the transmitter.
b. DYNAMIC MIC. 2 marks the location of the gain control and jack for Microphone T-50. This gain control is also used to control the output of Telephone EE-8-( ) when used in a remote position. The adjustment of the gain for Microphone T-50 and for remote Telephone EE-8-( ) is described in paragraph 51.
w)
^^\_^--^TLl6520
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/ El
W © JkZ^q
\ r
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/—---
A=r, ZZS-L^X-'--1 ,
- ' T L16 5 22
c. MODULATOR PLATE meter indicates the current in the plate circuit of modulator tubes V3 and V4. Its readings are controlled by the adjustment of the MODULATOR BIAS control on the transmitter panel and by adjustment of either microphone gain control on the speech-amplifier panel.
d. A red pilot lamp on the speech-amplifier panel is lighted when the transmitter FILA-
g. The eight-pin receptacle marked TO JB-70 is used to connect Cord CD-566 to Junction Box JB-70-A.
44. Junction Box JB-60-A Controls
a. LINE terminals are used to connect to Wire W-110-B (up to a mile in length) from the REMOTE terminals on Junction Box JB-70-A.
b. A KEY jack permits remote keying of the transmitter through the connecting field-wire line.
c. A cord marked EE-8 connects Telephone EE-8-( ) into Junction Box JB-60-A. The remote operator is thus able to modulate the transmitter and to hear the signals being received in the shelter.
45. Rectifier RA-63-(*) Controls
a. The rectifier main control switch has three positions marked TRICKLE, OFF, and HI CHARGE. In the TRICKLE position a low voltage is applied to the rectifier and enough charging current is supplied to the battery to
44
offset the load under operating conditions. In companying high charging rate of the battery, the OFF position no charge is applied to the b. The button marked PUSH TO RESET is battery. In the HI CHARGE position full used to reset the circuit breaker if it has opened voltage is applied to the rectifier with an ac- as a result of an overload.
Section II. TUNING
46. Preliminary Steps _________________________________
a. Safety Notice. Reread the safety notice
in front of book. (( (TY (TY (T/l
b. Receiver Disabling. (1) Always leave \k // \k J)
RECEIVER DISABLING switches on Junction ------
Box JB-70-A at ON. Z^^\@
(2) Always leave the SEND-REC. switches (( J J (( Jy Innl
on Radio Receivers BC-312-( ) and BC-342- Z^****^
( ) at SEND. ______ a
c. Gasoline Tanks. Never fill gasoline tanks — V^****/
© O °
( RECEIVER ------
r—[ DISABLING I- k ----------------------------------------
‘ \ of either truck or trailer when transmitter is
____\ in operation.
/ d. Power Unit PE-95-( ). (1) Start and y/ check the unit. Turn OFF THE large ON-OFF < switch marked CIRCUIT BREAKER (located /^n V 0/^ X on blc contr°l panel of the power unit). Check
the operation and condition of the power unit
Z"X \r V in accordance with procedure described in TM
\ 11-904.
® o©© / ___________________________________________________________
OOoooo
K z^x z©=©\©
/)y<-x lfFx\ (( H (( a n
/ / © ------ /s'-'A °
\ © o
\ OO O —-------------------------------------------l. 1,435
\ xz' (2) Stop the unit. When completely checked,
/ vzll 11(3 pUSh the ST0P button of the START-STOP
/ switch (on the control panel of the power unit)
/ and hold it until the power unit stons.
\ | I J~X Note. Some power units are issued which contain a
\ (1 momentary push-to-stop switch which does not have to
\________ ______________________ be held in until the power unit stops. In general, the
stop button must be held in on Ford-powered units, TL 14801 while Willys-powered units have the momentary push-to-stop switches.
----- ~~ (/) BATTERY SOURCE switch.
7^X\ 1' Power Unit PE-95-( ) is pro-
(( )) (( )) \x_)) \\}/ vided with 12-volt terminals and
x^—^z x/—JA Cord CO-316 is connected to these
terminals, set the BATTERY \\ Fna? \ r?=^i SOURCE switch on Junction Box
JB-70-A at PE-95.
------- ® ° m © © ° i
_________________™J 1
(3) Set circuit breaker. Set the ON-OFF
(CIRCUIT BREAKER) switch of the power M II CM ° ©I--------------
unit at ON. |g] B q
0 0)00) OOO 0
VI yr I TLI4803
_____________x\
\y
2* ^ie 12-v0^ supply in Chest CH-/ 109-A is to be used, set the BAT-
1----/ TERY SOURCE switch at AUX.
S and set the Rectifier RA-63-(*)
switch at TRICKLE. If Radio Re-ceiver BC-312-( ) is to be used, / set the rectifier switch at HJ
( CHARGE.
r~... r \_______________________________________
tl 14802 \ /V
J o //>}/
e. Position of Switches and Controls. (1) / J*/O'/ \
Speech Amplifier BC-61A-E. Rotate the gain I ZrV \
control knobs of both CARBON MIC. 1 and I buhL \
DYNAMIC MIC. 2 to their extreme counter- I. P"1 I""! n \
clockwise positions (minimum gain). Hjl |B| |M| 3
(2) Junction Box JB-70-A. (u) Set trans- j __ \
mitter main control switch at TRANS. OFF. / / y \
(6) Set C.W. SIDETONE switch at OFF. / \
(c) Set both receiver disabling switches / (Cj) v^v w
(marked RECEIVER DISABLING) at ON. / \^\ v£\ \
(d) Set RECEIVER OUTPUT switch at X\< \ \<\ /
NORMAL.
(e) Set REMOTE CONTROL EE-8 switch
at NORMAL. TLI4804
46
Caution: When Radio Receiver BC-312-( ) of the START-STOP switch. When the RE-
is to be turned off for more than 1 hour, turn CEIVER OUTPUT switch is set at NORMAL
the rectifier switch to TRICKLE. (par. 421), the left-hand pair of headset jacks
(g) See that key plugs are in proper jacks. is connected to Radio Receiver BC-312-( ) and
(3) Radio Transmitter BC-610-E. (a) Set the right-hand pair of headset jacks is con-
FILAMENT POWER switch at OFF. nected to Radio Receiver BC-342-( ).
(h) Set PLATE POWER switch at OFF. Note. When no commercial power is available, Power
/ \ „ ■. .. amadt l xx t x* t> tt> o/o / । ex ., . x onx/n Push the START button on Junction Box JB-
342-( ). Set SEND-REC. switches at SEND. A ... tt , . , , .
T ,. -XT - • 70-A until Power Unit PE-95-( ) starts and
Caution: Leave these switches in SEND posi- pickg up gpeed.
tion hl nil tiixiGs. STEP 2
f. Drying Out the Transmitter. Start Tllpn . . . .... . r,. , ^TT . n TT -x -nm n- / x . , ^TTA I urn on the electric lights m Chest CH-120-A,
Power Unit PE-95-( ) and turn on FILA- pi,,,. PTt 1Q1 a . • t u xi
watt TJMAATmD -X u r T? j• m -xx Chest CH-121-A, and m the shelter over the MENT POWER switch of Radio Transmitter transmitter
BC-610-E. In damp locations this should be
done at least 15 to 30 minutes before turning
on the high voltage. The drying process can be
accelerated by turning on the heater in the shelter.
g. Radio Receivers BC-312-( ) and BC- —------------------------------
342-( ). (1) Check the operation and condi- O o
tion of Radio Receivers BC-312-( ) and BC- O
342-( ) as outlined in TM 11-850. ~ Si
(2) Remove two Headsets HS-30-( ) with \ ODD [■} \ OF
Cords CD-605 from Chest CH-120-A. On June- \ N"
tion Box JB-70-A, plug one headset into one \
of the jacks marked HEADSET located to the \ (Q)
left of the START-STOP switch, and plug the ■ ----
other headset into one of the jacks to the right tli4808
47
COIL UNIT VACUUM CAPACITOR Zu TUNING UNIT
y । CHANNEL I CHANNEL 2 CHANNELS
7... • — — .
, ' & - :C ..•?:■ W'■ ... ■ \ fcJtt'
«l a
■ "JHWO" ■ 1 <* ’ IB
‘ । 4 |B
S& I II r>
IRtit - ’ZlXW
M . t ._ *♦•< A
II - bA x? « » *Eri /■k> »l j Kri© i Vwi
SBS& I® ’ ..|..\ .gaOl
('-U ': -^WBi^WTHrAi/n. 11if ih & fMk «•_
K.' IMBB*********“! ■**r; • ------I
■ .. - “ -----------------------------------------.
1 I
..--, -_______.......-
\ .','47'7' '3BI ass^w.
fefey 'i -j***
27x2*7. \ '^Lr •
Figure 30. Radio Transmitter BC—610—E, top covers removed.
STEP 3
Turn on the electric heater or the ventilating / '
blower, if either is desired. / vEy
STEP 4 / \
See that the PLATE POWER switch of the r------------------------------\
transmitter is at OFF and is left there. (See A © © \
j 4.0/v \ _—. \
\ / I □ □□ \
©^© V
/ (O/x STEP 6
\ 0 P Set the FILAMENT POWER switch of the
\ / transmitter at ON. The green pilot lamp and
TL.I4 3H the PLATE TUNING dial should now light.
The FIL. VOLTAGE meter should register.
STEP 5 • (Allow 1 minute for the filaments to come up
Make sure that the transmitter control switch to the proper operating temperature.) Adjust on Junction Box JB-70-A is at TRANS. OFF. the FILAMENT VOLTAGE control of the
48
__ STEP 8
I -----\ Open the right-hand door in the cover of the
Sm-— in?_____ transmitter and firmly insert the tuning unit
V___________________________ / in one °f the three available receptacles, marked
X 1, 2, and 3. (Locate the tuning unit so that the
\ / switch marked M.O.-XTAL faces the front
\ ---- ------- --- «■■■■» 7 panel of the transmitter.)
\ |^%] / STEP 9
\ '---' ----' '---- / From Chest CH-88-A, select one coil unit cov-
---- -----L----- / ering the desired frequency. Remove Capacitor
x i \ CA-423 from Chest CH-88-A, if operation in
i \ /""x /o i \ the 2.0-to 2.5-mc (megacycle) range is desired.
X I) Open the left-hand door in the cover of the
xp> X X < I
o/ 4 transmitter and insert the coil unit (and Capac-
X / 'y j itor CA-423 if required).
>------------' A---------\ STEp 10
/ X X s' Set the M.O.-XTAL switch of the tuning unit
/ X X \ at M.O.
/ ©XX ©
/ XXX □ □ --------
/ [3/ \ 0s
\ ®X\^/
T L 14 8 0 7 r
transmitter until the FIL. VOLTAGE meter 1— - ________ . I
indicates 5.0 to 5.3 volts. P) X Xi
STEP 7
From Chest CH-88-A, select one tuning unit x
XJ ovAy _ _ _ /
\ STEP 8 TUI48I0
A pIrrAniQU)
\ L VJ n®wR7 step 11
I 111 I) BAND SWITCH on the front panel of
fl 11 I --------- I / IPiAigV'i transmitter at the number which corre-
\ l / Ill'll U sponds to the socket in which the tuning unit
z k 7 » /AdrtP \ was placed.
/—/aLIx-----------n F ^T7a step 12
/ — \\<w>
49
STEP 14 for maximum reading as indicated on the EX-
Set the EXCITATION METER SWITCH on CITATION METER,
the front panel of the transmitter at INT. AMP.
GRID. Set the EXCITER PLATE POWER
switch of the transmitter at ON. Z^X.
ZL’Z
------ sVs x
r— Z\
ss <— T TF-y#
... >4______ oh© / [5|O|I3|5 A fl' S / XX
y*X V /r—i, , — A / Z Z xxZ
Cjtzt~~~-ZZJ nZ^v i xivNa-—zzz—
®\ \ pZj° L—X
O'-------\ ^B □□
nuait \ Z\
-^Xs\y ------
STEP 15
QTTpp IO
Loosen the thumbscrew lock on the M.O. dial
of the tuning unit. Set the M.O. dial to the de- Repeat steps 16 and 18 until the maximum pos-sired frequency as indicated by the tuning chart sible deflection *S °kRdned on ^he EXCITA-of Radio Transmitter BC-610-E which pertains ETER. The EXCITATION METER
to the tuning unit in use. For greater accuracy s ou d indicate between 60 and 100 ma (milliuse Frequency Meter Set SCR-211-( ). (See ‘™^GJ
TM 11-300.) Tighten the dial lock. m ___ _
STEP 16 the EXCITER PLATE POWER switch at
Adjust the center knob of the tuning unit ST^p^^l^ (marked DOUB) for maximum reading as indi- .
cated on the EXCITATION METER. certam that both doors m the top cover
of the transmitter are firmly closed upon the interlock switches; otherwise plate power can-= y not be applied.
STEP 22
\ . step^ Set the HIGH VOLTAGE PROTECT switch at
USt \ < HIGH V0LTAGE PROTECT. Always do this
ft ** A ,i- i,_ n before tuning the final amplifier or the antenna
p^pp|1/ tuning unit.
(o) IL© @( । -....................................... /
F I ° I \
# Zo © ----X
z_x A? DJbv/ /X X
= J-n STEP 23 X \C7
NZ (Q) U^ANS, OM >W Y
STEP 17
Set the EXCITATION METER SWITCH on (g) X3X
the front panel of the transmitter at P.A. GRID. Xs^ x_z xLz X
STEP 18 -----------------------------X
Adjust the INT. AMP. knob of the tuning unit TL14814
50
STEP 23
Set the transmitter control switch on Junction .______
Box JB-70-A at TRANS. ON. The red pilot \_____Z
lamp on the transmitter should now light. T— ______ g,,, 111 tti , \-\
step 24 A 'V Pw OO
Press and hold down Key J-37 while making \ (_____) X. J
subsequent tuning adjustments. The P.A. \ L_J *________
PLATE meter should indicate a flow of current \
in the circuit. The quantity of current will de- / (uWDJ z"-*\ \Uy /
pend upon the setting of the PLATE TUNING ( (vx) (
dial. \ \
1 \ 10 me. If a long wire antenna is used, set the
I \ knob at LONG WIRE. Set COUPLING IN-
------------------“ ' y CREASE control at about 2.0. From the tuning y 3ZX s' chart, determine the approximate setting of
k k^gi5 antenna tuning inductor for the selected fre-
\ / quency. Turn antenna tuning inductor crank
v to approach this setting and watch for an indi-
STEP 25 cation of rising plate current on the P.A.
Unlock the PLATE TUNING dial by pushing PLATE meter on the transmitter, down on the small knurled knob and adjust the Note. If the operating frequency is in the range of 2 wheel until the P.A. PLATE meter dips to a tncrf aUi^Vm c c marked FREQUENCY 10MC-
11N CKJLAbK-21VLC. If the operating frequency is m the minimum reading. ONCE THIS ADJUST- range of 10 to 18 me, use the crank marked FRE-
MENT IS MADE DO NOT CHANGE IT QUENCY 18MC-INCREASE-10MC. When the an-
IVilLlNl ID 1V1AU1L, VU 1NU1 UHAlWiL 11 tenna p g switch j t t LONG WIRE use the
UNTIL THE TRANSMITTER IS TO BE crank marked FREQUENCY 10MC-INCREASE-2MC.
TUNED ON A NEW FREQUENCY. Lock the be found that feweF turns. of tbe loadi.n£ coiJ
Will be necessary when a long wire antenna is used PLAIE 1 UNING dial by pushing the lock lever instead of a whip antenna.
to the right. Adjust the proper crank for maximum indica-
a______________ tion of the P.A. PLATE meter. Either increase
se7 ot262 o ynnriTz STEP 26 ”1 or decrease the degree of coupling with the
1 V LoJtJ y ^we’en^io^toisSc COUPLING INCREASE knob of the antenna ----\--------------------------' tuning unit to keep the P.A. PLATE meter Xen°2.oretqou ilX / f ------------------ reading at 100 ma. The ANTENNA CURRENT
■ y [—- KSet knob(see text) meter will now give some indication of antenna
current. _________________________
/ | STEP 27
n,4a,s Throw the HIGH VOLTAGE PROTECT switch of the transmitter to NORMAL. Press Key STEP 26 J-37. The P.A. PLATE meter of the transmit-
On Antenna Tuning Unit BC-939-A, set the ter and the ANTENNA CURRENT meter of
range switch knob at 2—10MC if operating the antenna tuning unit will now indicate sub-
below 10 me, or at 10-18MC if operating above stantially higher readings.
51
STEP 28 moment, throw the transmitter control switch
Alternately adjust the COUPLING INCREASE on the junction box to TRANS. OFF. control and the tuning inductor crank until the maximum antenna current occurs when the ____
P.A. PLATE meter reads 290 ma. f~ / > Z
/x r XXm A
w5SL_0 © fl I \ y STEP 2 8 "V [X
TLI48I9
yr’1 S
\ k pO°------------- Note. To turn off the transmitter completely, set
/ f the FILAMENT POWER switch on Radio Transmitter
\ I '' jr ---- T BC-610-E at OFF.
\ I ( | p > Table III. Tuning components
W\ Z7N Component Frequency Range (me)
/SXX (vA r—-—- Tuning Unit
I___I J TU-47 2.0 to 2.5
/ TU-48 2.5 to 3.2
X 7^\ /\ TU-49 3.2 to 4.0
V\® / x/ x. TL14818 TU-50 4.0 to 5.0
TU-51 5.0 to 6.35
TU-52 6.35 to 8.0
Caution: NEVER EXCEED A P.A. PLATE ™-53 8.0 to 12.0
1 U— 54 12.0 to 18 0
METER READING OF 300 MA on c-w opera- Coil Unit
tion. It is permissible to reduce coupling until C-387-B (with Capacitor 2.0 to 2.5
, V>A—4Zo )
plate current is as low as 200 ma, if satisfactory C-387-B 2.5 to 3.5
c-w communication is still maintained. Do not XoonX to
readjust the PLATE TUNING dial after it is C-390-A 5.7 to 8.0
once adjusted for the frequency on which opera- £-447 ,?’2 !°
. . . . , . , G-448 . 11.0 to 14.0
tion is to take place. C-449 14.0 to 18.0
STEP 29 ----:-------------------------
Release Key J-37. With the opening of the key, Table IV. Tuning ranges for long wire antennas when ,, nvnTr_mT_AT ~ , .A.’ used with Antenna Tuning Unit BC-939-A
the EXCITATION, P.A. PLATE, and AN-
TENNA CURRENT meters should return to Antenna lengths (ft.) | Useful frequency range (me)
zero. 25 2 to 10; 15 to 18
STEP 30 45 I !° }1 f° J!
Press Key J-37 and check the FIL. VOLTAGE 65 2 to 3 \ 9 to 18
meter. If necessary reset the FILAMENT --------------—-------------------------—
VOLTAGE knob until this meter reads 5.0 to
5.3 volts; then release the key. This completes 48. Tuning Radio Transmitter BC-6I0-E for
the tuning procedure, and the transmitter is C-W Operation [Crystal Control]
ready for c-w operation. Keying of the trans- STEP 1
mitter may be checked by depressing the key Perform all operations in steps 1 through 9 and
and noting the meter indications. Data on meter 11 through 13 in paragraph 47, then proceed
readings will be found in the equipment per- as follows:
formance check list. (See par. 66.) STEP 2
STEP 31 Set the tuning unit M.O.-XTAL switch at
If c-w transmission is not desired at the XT AL. Insert into XT AL jack Crystal Holder
52
FT-171-B with a crystal of proper frequency as listed in table V.
Note. At frequencies between 2 and 4 me, the trans- I/"—xYk
mitter output frequency is the same as the crystal fre- y ( \ ' ) Yx. \
quency and a circuit controlled by the DOUB. knob / <----1 ■--------' r
functions as a buffer stage. At frequencies between 4 i ________________J _________LL__\ o
and 12 me, this stage acts as a doubler; hence the out- /
put frequency is twice that of the crystal. For example, — I
a crystal with a frequency of 2,200 kc (kilocycles) may ( ((O)))
be used with Tuning Unit TU-47 to produce the same
frequency in the transmitter output or it may be used ^\> W? "Sv
with Tuning Unit TU—50 to operate the transmitter on I
4,400 kc. At frequencies between 12 and 18 me this
stage quadruples the crystal frequency. For example, Y ' 1 ~ ~~~~T
a 4,000-kc crystal will produce a transmitter output / /
frequency of 16,000 kc. / O O /
STEF 3 ~ \
Set the EXCITATION METER SWITCH on / O M \
the transmitter at INT. AMP. GRID. Set the / [■■I fl I"1 /
EXCITER PLATE POWER switch on the / 3 / LJ U U V
transmitter at ON. / \ /
STEP 4
Perform all operations listed in steps 16
through 30, paragraph 47. TL,482°
Table V. Crystals and operating frequencies
Note. Radio Sets SCR-399-A and SCR-499-A include* two sets of Crystal Holders FT-171-B whose crystals have the following operating frequencies. For convenience, a third column is included to show the additional operating frequencies which may be obtained by use of different tuning units. Two groups of crystals are shown, only one of which is supplied with each set.
GROUP 1 GROUP 2
Crystal Operating Tuning Additional possible Tuning Crystal Operating Tuning Additional possible Tuning
frequency frequency Unit operating frequencies Unit frequency frequency Unit operating frequencies Unit
(kc) (kc) (kc) (kc) (kc) (kc)
2,030 2,030 TU-47 4,060 TU-50 2,030 2,030 TU-47 4,060 TU-50
2,220 2,220 TU-47 4,440 TU-50 2,052.5 2,052.5 TU-47 4,105 TU-50
2,258 2,258 TU-47 4,516 TU-50 2,085 2,085 TU-47 4,170 TU-50
2,300 2,300 TU-47 4,600 TU-50 2,117.5 2,117.5 TU-47 4,235 TU-50
2,360 2,360 TU-47 4,720 TU-50 2,160 2,160 TU-47 4,320 TU-50
2,390 2,390 TU-47 4,780 TU-50 2,200 2,200 TU-47 4,400 TU-50
3,510 3,510 TU-49 7,020 TU-52 2,217.5 2,217.5 TU-47 4,435 TU-50
3,520 3,520 TU-49 7,040 TU-52 2,390 2,390 TU-47 4,780 TU-50
3,550 3,550 TU-49 7,100 TU-52 2,415 2,415 TU-47 4,830 TU-50
3,570 3,570 TU-49 7,140 TU-52 2,436 2,436 TU-47 4,872 TU-50
3,580 3,580 TU-49 7,160 TU-52 2,532.5 2,532.5 TU-48 5,065 TU-51
3,945 3,945 TU-49 7,890 TU-52 2,647.5 2,647.5 TU-48 5,295 TU-51
3,955 3,955 TU-49 7,910 TU-52 2,772 2,772 TU-48 5,544 TU-51
2,045 4,090 TU-50 2,045 TU-47 2,980 2,980 TU-48 5,960 TU-51
2,065 4,130 TU-50 2,065 TU-47 3,000 3,000 TU-48 6,000 TU-51
2,105 4,210 TU-50 2,105 TU-47 3,035 3,035 TU-48 6,070 TU-51
2,105 4,210 TU-50 2,105 TU-47 3,100 3,100 TU-48 6,200 TU-51
2,125 4,250 TU-50 2,125 TU-47 3,120 3,120 TU-48 6,240 TU-51
2,145 4,290 TU-50 2,145 TU-47 3,150 3,150 TU-48 6,300 TU-51
2,155 4,310 TU-50 2,155 TU-47 3,155 3,155 TU-48 6,310 TU-51
2,260 4,520 TU-50 2,260 TU-47 3,232.5 3,232.5 TU-49 6,465 TU-52
2,282.5 4,565 TU-50 2,282.5 TU-47 3,265 3,265 TU-49 6,530 TU-52
2,290 4,580 TU-50 2,290 TU-47 3,322.5 3,322.5 TU-49 6,645 TU-52
2,305 4,610 TU-50 2,305 TU-47 3,417.5 3,417.5 TU-49 6,835 TU-52
2,320 4,640 TU-50 2,320 TU-47 3,475 3,475 TU-49 6,950 TU-52
2,415 4,830 TU-50 2,415 TU-47 3,588 3,588 TU-49 7,170 TU-52
2,435 4,870 TU-50 2,435 TU-47 3,665 3,665 TU-49 7,330 TU-52
2,442.5 4,885 TU-50 2,442.5 TU-47 3,725 3,725 TU-49 7,450 TU-52
2,532.5 5,065 TU-51 2,532.5 TU-48 3,785 3,785 TU-49 7,570 TU-52
2,545 5,090 TU-51 2,545 TU-48 3,792.5 3,792.5 TU-49 7,585 TU-52
2,557.5 5,115 TU-51 2,557.5 TU-48 3,850 3,850 TU-49 7,700 TU-52
3,202.5 6,405 TU-52 3,202.5 TU-49 3,865 3,865 TU-49 7,730 TU-52
3,215 6,430 TU-52 3,215 TU-49 3,905 3,905 TU-49 7,810 TU-52
3,237.5 6,475 TU-52 3,237.5 TU-49 3,935 3,935 TU-49 7,870 TU-52
3,250 6,500 TU-52 3,250 TU-49 3,995 3,995 TU-49 7,990 TU-52
3,322.5 6,645 TU-52 3,322.5 TU-49 3,997.5 3,997.5 TU-49 7,995 TU-52
______________________________________________________I ______________I___________________________________________
53
Note. Although no crystals are included for fre- tion. (This increases the bias so that the MOD-
quencies above 8 me, the following examples show typi- ttt atAP PT ATF motor Inoatod nn Snoorh Am-
cal crystal and operating frequencies in this range. U^A 1 UK FLA 1 IL meter, located on bpeecn Am-
plifier BC-614-E, will not indicate until further crvstai uncrating Tuning adjustments have been made.) Set the C.W.-
ZXZ /SX> TuZ pH0NE switch at pH0jjE.
4,500 9,000 TU-53 Caution: Never throw this switch while the
5,500 11,000 TU-53 n . • 4- u
3 5Q9 14 ooo TU-54 final amplifier is turned on.
4’500 is’ooo TU-54 STEP 4
■--—---------------------------------- Remove Microphone T-50 from its mount in
Chest CH-120-A and connect it to the recep-49. Tuning Radio Transmitter BC-6I0-E taele marked DYNAMIC MIC. 2 located on the
for Voice Operation speech-amplifier panel.
STEP 1 ______________
Perform all operations in paragraph 47 or 48 [✓‘“xl I---1
(depending upon whether the operation is to (©) © Q_j I—
be m-o controlled or crystal controlled), then (g) © 11 1
proceed as follows:
nZ Z/z ° V»V
x^< D II
STEP 2 k °
On Junction Box JB-70-A set the transmitter \z
control switch at TRANS. OFF. Set REMOTE
CONTROL EE-8 switch at NORMAL. Set STEP 5
C.W. SIDETONE at OFF Press the switch on the microphone and note
, that this puts the transmitter carrier on the
k________ air. The P.A. PLATE meter should read ap-
( Adjustuee text) y lAIDT proximately 250 ma, which is the normal plate
v = current for voice operation. If the transmitter
\y\ r-1© /Ox
xAJ 1 //^X
vu., /zx\
1/ WwaA—
I ^0 1 I I la
j STEP 3 X 1 Bl/
Extreme X (6) Bhi ■■ I______I /
I counterclockwise^/ yl Z
\ / TLt4822 -- --------- \
STEP 3 (fcy) ® \
Set the MODULATOR BIAS control on trans- —
mitter to the extreme counterclockwise posi- J--------------------S
<____________________Z T L14 8 2 4
54
has been tuned to 290 ma on c-w operation, the STEP 9
plate current will be 250 ma when switched to When REMOTE CONTROL EE-8 switch is in
voice because the C.W.-PHONE switch auto- either TELEPHONE position, voice transmis-
matically reduces the final amplifier plate volt- sion can be obtained without pressing the mi-
age. If the P.A. PLATE meter reads more than crophone switch. When using this method, set
260 ma, the COUPLING INCREASE control the transmitter control switch at TRANS. ON
on the antenna tuning unit should be adjusted during transmission periods and to TRANS,
until the plate current is reduced to the proper OFF to terminate transmission. This procedure
value. is not recommended for general practice.
STEP 6 STEP 10
Hold the microphone in the left hand, press the To turn transmitter off completely, set the
microphone switch, and with the right hand ad- transmitter control switch on Junction Box JB-
just the MODULATOR BIAS control on the 70-A at TRANS. OFF and set FILAMENT
transmitter until the MODULATOR PLATE POWER switch on the transmitter at OFF.
meter on Speech Amplifier BC-614-E indicates
40 ma. Release the microphone switch. .» -... ■ ....■ =y
STEP 7 H-------------------------------C
Hold the microphone in the normal speaking --------- \
position (position varies with voice character- z—x -y
istics, from 2 to 6 inches from mouth), press oJTRa^i \ H Ol r
the microphone switch, and speak into the mi- Pjf— x JI /
crophone. While pressing the switch and talk- (Qj f
ing into the microphone, adjust the gain control (£§}) dp})((§)) xrz
(marked DYNAMIC MIC. 2) until the MODU-LATOR PLATE meter indicates approximately ----------------------------------------'
200 ma on voice peaks. If the pointer swings higher than 200 ma on extreme voice peaks, ---
reduce the gain control to prevent exceeding . _________w' ■
200 ma. (This figure represents 100 percent __________________ /
modulation when the transmitter is fully \
loaded.) The same procedure applies to the use J------------ \
of carbon Microphone T-17. Only one gain con- I \f7
trol should be open (turned away from the O I___J _____) (__. L_/
position) at a time, however. ____ ______U---- |/
STEP 8 7
Release the microphone switch, taking the /C?\ /
transmitter off the air. Voice transmission can x <
now be accomplished by pressing the micro- x.
phone switch and speaking into the microphone.-------------------------------------X
I \ |STEP|0 \ 'X
O'A I A
© ©@© \
TLI4825 TL14826
55
Section III. NORMAL OPERATION
Caution: Before attempting operation of the minute for the filaments to reach operating equipment, read paragraphs 38 through 46. temperature. See the transmitter C.W.-PHONE When thoroughly familiar with their contents, switch at C.W. proceed with the operation of the set.
50. C-W Operation
To operate the transmitter on continuous wave, perform the following steps: Zv
STEP 1 >— KZ^ VJZ^
Push ST ART button on Junction Box JB-70-A / / G^/Z
until Power Unit PE-95 starts and picks up \ q .
speed. J n
------------, lx. OSO ©
F - - a --------------------1
/ \ V TLI4827
/ 7 STEP 4
/ ________ Set the transmitter control switch on Junction
/ II V ^2^ Box JB-70-A at TRANS. ON.
V I -------------------------- ।1 (
\ ------1 \
\----------------------------- I ■■ /Zxn /
TL18001 (SlTrans. off f
STEP 2 (qJ O I
Turn on the electric lights in Chest CH-120-A, tgj ({§)) \
Chest CH-121-A, and in the shelter over the ______ \
transmitter. '
ifWz© 5 i— z
\ xrf 3k -v S pin py
x ©> _ qJ xA, \ J \ '5=^ (§> ©
/X-J0 □ □ 0 J---------------------------------------------------(
/ I °ff >n □ o □
TL 14828
STEP 3 /x O (□
See that the PLATE POWER switch of the x. < x.
transmitter is OFF. Set FILAMENT POWER x. / switch of the transmitter at ON and wait 1 \Z
56
STEP 5 5|, Voice Operation
Set the C.W. SIDETONE switch in the position To operate the transmitter on voice, perform corresponding to the receiver being used. the following steps:
STEP 6 STEP 1
Use Key J-37 to send any desired messages. In Perform all operations in steps 1 through 3, addition to Keys J-37 located in the operating paragraph 50.
chests, Key J-45 may be used to key the trans- STEP 2
mitter at the auxiliary KEY jack located on the Set the transmitter control switch on Junction front of the speech-amplifier panel. Keying of Box JB-70-A at TRANS. OFF, and the C.W. the transmitter at the auxiliary key jack will SIDETONE switch at OFF. be necessary if the source of 12-volt d-c power STEP 3
fails, since the auxiliary jack is the only direct Set the C.W.-PHONE switch of the transmitter connection to the cathode circuit of the trans- at PHONE, mitter oscillator. STEP 4
Press the microphone switch on Microphone —1T-50, and speak into the microphone to modu-
/ x । —/
/ ,—® A /
\-----------/pSuw-------------/ tel o f
\ Qj I (g) k
< Z\p n □
x. / x. ./X J , 1^
tli483o rZZZZZZZ X
Caution: Relay RY200 does not function with I/^nI K\|
this method of keying; therefore, automatic re- C___J .___J C__, C /
ceiver disabling cannot occur. See paragraph ____ _____U____ 7
43 before using this jack. Z7
STEP 7 vOR (J
To turn the transmitter off completely, set the 'xZ^xN (xX) /
transmitter control switch on Junction Box JB- (
70-A at TRANS. OFF, and set the FILAMENT_____________________________\
POWER switch on the transmitter at OFF. 1°; U
use, and setting the transmitter control switch I Xfe,- sXf I
to TRANS. ON. 1
b. Changing from Continuous Wave to 'mPIM PI
Voice. After the transmitter has been operated A
® ।--1
11 ~ - y © ’
□ 0 NORMAL
/x lx \
(Qj [qV \ X/
_. I s T E PI a 4 fl \ x.
Km I See tp ♦ >11 'i tuning units, each of which may be instantly
nruji eX*/M selected by the BAND SWITCH. Each tuning
Jr unit may be tuned to a separate frequency and
ZSk z2S\ z^\/~x \>-> left Pegged in ready for use when needed.
O) (©/ (©)(©) Since there are three sets of tuning units, it is
X possible to install three tuning units of the same
* f range which would be covered by one coil unit.
TLI4837 With each unit pretuned to a different frequency on continuous wave, it can be switched imme- within the ran?e’ change of transmitting fre-
diately to voice by resetting the transmitter quency 1S accomplished as follows:
control switch at TRANS. OFF, setting the STEP 1
C.W. SIDETONE switch at OFF, and then set- Set the transmitter control switch at TRANS,
ting the C.W.-PHONE switch at PHONE. OFF if operating on continuous wave. Release
the- microphone switch if operating on voice.
53. Changing Frequency STEP 2
a. Case 1. Provision is made in the transmit- ReSet the BAND SWITCH to the desired chanter for simultaneously accommodating three nel numfoer
/X STEP 3
XX J Set the HIGH VOLTAGE PROTECT switch at
HIGH VOLTAGE PROTECT.
XJFB STEP 4
/q\ Set the transmitter control switch to TRANS.
__ I X7 ON and close the key if operating on continuous
.—./ wave. Leave the transmitter control switch at
ZXx3 X TRANS. OFF and press the microphone switch
if operating on voice.
/ STEP 5
-------------------1 Slightly retune the PLATE TUNING dial for a / a dip in the P.A. PLATE meter.
VTX<5 71-1 > STEP 6
/ Adjust the proper antenna tuning inductor
crank for a rise in indication of the P.A. PLATE meter.
59
STEP 7 quency range of the coil unit is correct. If not,
Throw the HIGH VOLTAGE PROTECT switch remove it and replace it in Chest CH-88-A. to NORMAL. STEP 2
STEP 8 Set the BAND SWITCH to the desired channel
Adjust the COUPLING INCREASE control of number.
the antenna tuning unit until the P.A. PLATE step 3
meter reads 290 ma (on continuous wave) or T x n -i -x xi p
\ r> x xi x • -ix Install a coil unit of the proper frequency.
250 ma (on voice). Reset the tuning inductor J
crank for maximum indication of the AN- STEP 4
TENNA CURRENT METER. Close the cover doors. Set the C.W.-PHONE
Note. When the difference in frequency is small, switch of the transmitter at C.W. only steps 1, 2, and 4 may be necessary, though disre-
garding the other steps is not recommended. STEP 5
____________ Since the tuning unit has been tuned previously, "___________for c"w °Peration it will be necessary to tune
|____J a on]y the final and antenna circuits as outlined
J '--1 in steps 22 through 31 in paragraph 47. If voice
/m?) z-x \ Set BAND SWITCH I operation is required, throw the C.W.-PHONE
switch to PHONE at the completion of step 31,
/ _____ A--------------1 paragraph 47,
\ ® ° \ I
\ © ©I 1 54. Presetting Tuning Units
\ n □ o 0 J Tuning units may be tuned one after another
I for m-o operation by following steps 5 through
18002
b. Case 2. When the three tuning units _
plugged into the transmitter cover two or more 1 J 1 H~P H-"
different frequency ranges, it is necessary to \ -----U----J (----J
proceed as follows: \ /TX
r----------------7 ) ® ®
A rt AAA-------------------------------------------------------------
/ r—L/ /© x*©
/ /7 \ □ □ □ □
I I \ \
31 I \ \ -——____________________________—
/ / TL 14839
P —f \ 20, paragraph 47, or for crystal-controlled op-
I____\ eration by following steps 1 through 4, para-
x \ / graph 48.
‘ ___
STEP 1 55. Additional Operating Instructions
Before moving the BAND SWITCH to the de- a. When Station Is In Motion. Speak into sired channel number, open the cover door over the microphone with the lips almost touching it the coil unit and determine whether the fre- so as to exclude unwanted noises. To avoid over-
60 modulation, readjust the gain control on the (3) Use an auxiliary transmitting antenna, speech amplifier. Use of Microphone T-30 ... _ xx- x-xt
/xx x\ • i j j 4? j • xi (4) Decrease the setting of the COUPLING
(throat) is also recommended for reducing the a n-n x , x, x x
, n + i • INCREASE control on the antenna tuning unit
ex erna oise. until the P.A. PLATE meter reads 200 to 210
b. During Transmission On Critical Fre-
quency. The frequency range of 2 to 2.5 me is
critical in damp weather and at high altitudes z'^X
because extreme voice peaks may cause flash- / /XX
overs. These trip the overload relay which mo- / / / ^^X^X
mentarily interrupts communication until the /X/xZX
relay is reset. If this should happen, do one of \\Xj >^4__________________________
the following: x N \ J -----
X/X O • IQI_____________________
S'" il ‘—1
3 0 © Q © 0
X—-___ ------------------------------------------------------------1--— TLI484I
31 ma. DO NOT REDUCE BELOW 200 MA.
CY Under this condition less modulation is re-
@ quired; therefore the gain control should be ad-
__________________justed so that voice peaks do not cause swings Z_________________above 150 ma on the MODULATOR PLATE
© © meter.
0 □ □ □
J c. Overload Reset Switch. If the high-volt-
age circuits are overloaded (by excessive plate
(1) Switch to a more favorable operating cu’Tent plus heavy modulation) the overload frequenev relay will trip and shut off the plate power. In
this case, press the OVERLOAD RESET switch
(2) Stop the truck and transmit from a fixed on the front panel of the transmitter and proposition after unguying the antenna and insert- ceed with the transmission. If the overload pering one or two Mast Sections MS-54 to provide sists, check tuning adjustments and meter read-added height. ings.
Section IV. REMOTE CONTROL OPERATION
Note. The description of remote control operation and STEP 1
power source operation for Radio Set SCR-399-A is .. . . „ . . „„ « , k
given below. These instructions will apply equally to Remove the unconnected Telephone EE—8—( )
d^t°d^e^ SCR“499-A references to the truck are from its mounting compartment in Chest CH-
121-A. Before leaving the truck, make sure the telephone batteries are in good condition and
56. Connection of Remote Stations the screw switch is set to LB.
A complete description of the equipment and STEP 2
facilities provided for remote control will be Remove Junction Box JB-60-A and Key J-45 found in paragraphs 16 and 23. Follow the from Chest CH-121-A.
steps below in connecting the remote control STEP 3
equipment. Remove Axle RL-27-B from Chest CH-89-A
61
for use with either or both Reels DR-4 which should be dismounted, as required, from Frame FM-59-A.
STEP 4
Carry Telephone EE-8-( ), Junction Box JB-60-A, and Key J-45 to the point where remote control is to be established.
STEP 5
Connect the cord of Junction Box JB-60-A at terminals Lx and L2 of Telephone EE-8-( ). STEP 6
Insert the plug on the cord from Key J-45 into the jack on Junction Box JB-60-A.
STEP 7
Using Wire W-110-B from Reel DR-4, run the line between the remote station and the radio station in the truck. (If less than one full reel of wire is used, do not cut the wire, but pull out the inner end from the center of the reel.) In some cases it will be more convenient to leave reels of wire in Frame FM-59-A and pay out the wire through the fairleads in the back of the shelter.
STEP 8
Connect the two leads of one end of the line to the two line terminals on Junction Box JB-60-A.
STEP 9
Connect the leads at the other end of the line to terminals marked REMOTE TELEPHONE outside Junction Box JB-70-A. The telephone at the remote station is not connected to the telephone in the truck. Communication between these two points may be established by operating Telephone EE-8-( ) in accordance with instructions contained in TM 11-333.
57. Remote Voice Operation
a. The remote station operator may now request the radio operator at the truck to turn on the radio transmitter for voice operation and to adjust the speech-amplifier gain so that the remote station can properly modulate the transmitter. This is accomplished by following the procedure outlined in step 7, paragraph 49, and in step 4, paragraph 51. It should be noted that both telephones are on the same circuit and accordingly both share the same facilities. Therefore, the radio operator may switch in the output of either receiver so it may be heard at the remote station.
b. Since the transmitter cannot be operated by pressing the microphone switch when using a telephone line, the remote operator should signal the radio station operator when end of transmission is desired. The radio station operator can throw the transmitter control switch to obtain reception or shut down the station, as required.
58. Remote C-W Operation
a. If remote keying of c-w transmission is desired, the radio station operator should be instructed to place the transmitter in c-w operation and to set the REMOTE CONTROL EE-8 switch on Junction Box JB-70-A to either TELEGRAPH position. Then Key J-45 at the remote location can be used to key the transmitter.
b. Remote keying of the transmitter in two-way communication or net operation may be accomplished without the assistance of a radio station operator if there is an independent means of reception at the remote station.
59, Remote Receiver Operation
When necessary, Chest CH-121-A with Radio Receiver BC-312-( ) may be removed from the truck to a remote point for operation. This is accomplished as follows:
STEP 1
Disconnect the antenna lead from the fitting at the top of the chest.
STEP 2
Disconnect the key cord and the main audio cord between Chest CH-121-A and Junction Box JB-70-A.
STEP 3
Disconnect Plug PL-114 of Cord CD-565 from Socket SO-94 on the receiver.
STEP 4
Disconnect the ground strap from the terminal under Chest CH-121-A.
STEP 5
After removing safety wires from wingnuts, loosen the turnbuckles holding Chest CH-121-A to the table frame in Shelter H0-17-A.
STEP 6
Remove Chest CH-121-A from the shelter.
62
STEP 7
Remove Chest CH-109-A (12-volt battery) after pulling out the plug of Cord CH-659.
STEP 8
Remove the four legs from the top of Chest CH-120-A and one each Mast Sections MS-51, MS-52, and MS-53 from Chest CH-89-A.
STEP 9
Move the two chests, the legs, the mast sections, and Cover BG-143-A to the desired location. STEP 10
Set up Chest CH-121-A on its legs. (See fig.
13.)
STEP 11
Remove Cord CD-690 from Chest CH-121-A
and connect it between Chest CH-109-A and the receiver.
STEP 12
Screw the mast sections together and into the fitting in the top of Chest CH-121-A.
STEP 13
Remove the headset from Chest CH-121-A and plug it into the PHONES jack on Radio Receiver BC-312-( ). The receiver is now ready for operation.
STEP 14
If the radio station is to be operated with Chest CH-109-A removed as described above, turn the switch on Rectifier RA-63-(*) to FULL CHARGE to furnish 12-volt power for relays.
Section V. POWER SOURCE OPERATION
60. Operation from Commercial Power Source Operation from a 117-volt, 50/60-cycle, singlephase, a-c commercial source may be effected as follows:
a. Plug one end of Cord CD-652 into the power plug at the rear of the truck and plug Cord CD-314 into the other end of the power plug.
b. Connect the leads from the other end of Cord CD-314 directly to the source of power.
61. Operation of Trailer 100 Feet From Truck
a. Disconnect the trailer power Cord CO-316 from Cord CO-335 at the bumper clamp underneath the rear of the truck. (See fig. 27.) Also disconnect the cable which delivers power to the running lights on the trailer.
b. Unhitch the trailer from the truck.
c. Drive the truck to any point up to 100 feet from the trailer.
d. Remove Cord CD-652 from Chest CH-119-A.
e. Insert one end into the plug in the bumper bracket of the truck, then insert the other end into the plug on the power cord of the trailer. Operation may now proceed normally with remote control of the power unit from the transmitter location.
62. Operation of Trailer 200 Feet From Truck
a. Proceed as in paragraph 61a and b, but drive the truck to any point within 200 feet of the trailer.
b. Remove Cord CD-652 from Chest CH-119-A, Cord CO-314 from the seat bench, and
Cord CO-313 from Chest CH-112-A in the trailer.
c. Insert one end of Cord CD-652 into the power plug at the rear of the truck. Insert the plug of Cord CO-314 into the other end of this cord.
d. Twist the leads of Cord CO-314 around the terminals of Cord CO-313 and tape up these connections.
e. Insert the plug of Cord CO-313 into the power plug at the trailer. Operation of the power unit at distances greater than 100 feet is an emergency measure, and is not ordinarily used. Therefore it will be necessary to start or stop Power Unit PE-95-( ) at the trailer instead of at the transmitter location.
63. Use of Power Unit PE-95-( ) to supply power to Auxiliary Equipment
a. If the radio set is not in use, power may be supplied at distances up to 200 feet from Power Unit PE-95-( ) as follows:
(1) Remove the plug of the trailer power cord from the plug at the rear of the truck.
(2) Connect one end of Cord CD-652 to the trailer power cord.
(3) Plug Cord CO-313 into the other end of Cord CD-652. Connect the load to the terminals at the end of Cord CO—313 and start the power unit.
b. If Radio Set SCR-399-A or SCR-499-A must be used while the auxiliary power is being generated, proceed as follows:
(1) Leave the trailer connected and hitched to the truck.
63
(2) Connect the terminals of Cord CO-313 to the a-c terminals on the power panel of Power Unit PE-95- ( ).
(3) Plug Cord CO-314 into the other end of Cord CO-313.
(4) Connect the bare ends of Cord CO-314 to the load. With the radio set and the heater in operation, this additional load should not exceed 1 kilowatt. If the heater is not being used, the total external load may be 2.5 kilowatts. Before operating in this manner, check the rated capacity of the power unit.
64. Operation of Low-voltage Power Supply System
a. The 12-volt battery system is used to furnish power for Radio Receiver BC-312-( ), as well as for operating the keying relay and the disabling relays.
b. With the BATTERY SOURCE switch on Junction Box JB-70-A at AUX. (par. 42e), the 12-volt supply is obtained from the 12-volt bat-
EQUIPMENT PERFORMANCE CHECK LIST
Section VI.
65. Purpose and Use
a. General. The equipment performance check list (par. 66) will help the operator determine whether Radio Set SCR-399-A or SCR-499-A is functioning properly. The check list gives the item to be checked, the conditions under which the item is checked, the normal indications and tolerances of correct operation, and the corrective measures that the operator can take. Items 1 to 28 are checked before starting, items 29 to 34 when starting, items 35 to 44 during operation, and items 45 to 49 when stopping. Items 35 to 44 on this check list should be checked at least once during a normal operating period or at least four times a day during continuous operation.
b. Action or Condition. For some items the information given in the action or condition column consists of the settings of various switches and controls under which the item is to be checked. For other items it represents an action that must be taken in order to check the normal indication given in the normal indication column.
c. Normal Indications. The normal indications listed include the visible and audible signs that the operator will perceive when he checks the items. In the case of meter readings, the allowable tolerances of the readings are given. When a meter reads between the limits speci
tery in Chest CH-109-A.
c. Rectifier RA-63-(*) charges the battery in Chest CH-109-A. When using this battery, turn the switch on the rectifier to TRICKLE. If the battery is low, set the switch on the rectifier at HI CHARGE.
d. Keep the battery fully charged at all times. Do not let the level of the electrolyte fall so low that the plates become uncovered. Check the state of charge of the battery with the hydrometer provided.
e. Some Power Units PE-95-( ) are provided with 12-volt terminals. With Cord CO-316 connected to these terminals, the 12-volt supply may be obtained from the power unit by setting the battery switch on Junction Box JB-70-A to PE-95.
/. With Chest CH-121-A and Chest CH-109-A removed from the shelter as described in paragraph 59, the 12-volt supply for the radio station relays is obtained from Rectifier RA-63-(*) with its switch set at HI CHARGE.
fied, operation can be considered satisfactory. A meter reading outside the limits given is a sign of impending trouble. If the indications are not normal, the operator should apply the recommended corrective measures.
d. Corrective Measures. The corrective measures listed are those that the operator can make without turning the equipment in for repairs. A reference to part five in the table indicates that the correction of the trouble cannot be effected during operation and that trouble shooting by an experienced repairman is called for. If the set is completely inoperative or if the recommended corrective measures do not yield results, trouble shooting is necessary. However, if the tactical situation requires that communication be maintained and if the set is not completely inoperative, the operator must maintain the set in operation as long as it is possible to do so.
e. Items 1 to 34. Items 1 to 34 should be checked each time the equipment is put into operation.
f. Items 35 to 38. Items 35 to 38 show correct meter readings when the transmitter is properly tuned and in operation.
g. Items 39 to 44. These items represent general operating characteristics of the radio set. The operator must become familiar with the characteristics of the set during normal opera
64
tion; he must use that knowledge as a basis for recognizing changes in audible and visible indications, such as relay clicks, sidetone, flicking of the meter needles, etc., when the set is not operating properly. By becoming familiar with the operation of the receiver, the operator will know the normal position of the VOL control. This will aid in determining the sensitivity and
amplification of the receiver.
h. Items 45 to 49. Items 45 to 49 are checked whenever the station is taken out of operation. Any abnormal indications at this time are probably caused by trouble in the set and should be corrected before the next expected period of operation.
66. Check List
a. Power Unit PE-95-( )
Item No. Item Action or condition Normal indications Corrective measures
PREPARATORY 1 CIRCUIT BREAKER ON-OFF switch. (Main power switch if commercial power source is used) Set at ON
b. Junction Box JB-70-A
Item No. Item Action or condition Normal indications Corrective measures
PREPARATORY 2 3 4 5 6 7 8 9 10 Transmitter control switch C.W. SIDETONE switch REMOTE CONTROL EE-8 switch Keys J-37 BATTERY SOURCE switch 1 RECEIVER OUTPUT switch Headsets HS-30-( ) RECEIVER DISABLING switches RECEIVER OUTPUT switch Set at TRANS. OFF Set at OFF for voice transmission. Set at TO BC-312 or TO BC-342 for c-w transmission a. Set at NORMAL unless remote control operation of transmitter is desired b. Set at TO BC-312 TELEPHONE or TO BC-342 TELEPHONE for remote voice operation c. Set to proper TELEGRAPH position for remote c-w operation Keys plugged in KEY jacks a. Set at PE-95 if 12-volt supply of Power Unit PE-95-( ) is used b. Set at AUX. if 12-volt supply in Chest CH-109-A is used Set at NORMAL Headsets plugged into proper HEADSETS jacks (one on either side of START-STOP switch) Set both switches at ON Set at NORMAL unless headsets are to be transposed
65
66. Check List (Con+'d)
c. Rectifier RA-63-(*)
Item No. Item Action or condition Normal indications Corrective measures
PREPARATORY 1 1 Main control switch If 12-volt battery in chest is used, set switch at TRICKLE
d. Radio Receivers BC-312-( ) and BC-342-( )
Item No. Item Action or condition Normal indications Corrective measures
PREPARATORY 12 13 14 15 SEND-REC. switches BAND CHANGE switches FAST TUNING control C.W.-OSC. switch Set both switches at SEND Set to correct band Set to approximate frequency required a. Set at ON for c-w reception
e. Radio Transmitter BC-610-E
Item No. Item Action or condition Normal indications Corrective measures
16 FILAMENT POWER switch Set at OFF (down)
17 PLATE POWER switch Set at OFF (down)
13 EXCITER PLATE POWER switch Set at NORMAL (down)
19 HIGH VOLTAGE PROTECT switch Set at NORMAL (down)
20 C.W.-PHONE switch Set at C.W. or PHONE, as desired
P4 21 Tuning units Check selection of proper tuning unit
O H P4 22 BAND SWITCH Set to channel corresponding to desired tuning unit
-W Ph - 23 Coil unit Check selection of proper coil unit for frequency desired
24 M.O.-XTAL switch of tuning unit a. Set switch at M.O. for master-oscillator control b. Set switch at XTAL for crystal-frequency control. Check selection of proper crystal holder for frequency desired
25 PLATE TUNING wheel Has been set to proper reading
66
66. Check List (Con+'d)
f. Antenna Tuning Unit BC-939-A
Item No. Item Action or condition Normal indications Corrective measures
26 Antenna range switch Set to desired band
o 27 COUPLING INCREASE Has been set to desired
<1 knob position
28 FREQUENCY crank Crank for band being
used has been set to
P4 Oh • desired position
g. Junction Box JB-70-A
Item No. Item Action or condition Normal indications Corrective measures
START 29 30 START button Electric lights Push START button to control Power Unit PE-95-( ) Turn on electric lights in Chest CH-120-A, in Chest CH-121-A, and in shelter over transmitter Power Unit PE-95-( ) starts Normal line voltage (110-125 volts) indicated on A.C. VOLTAGE meter on Power Unit PE-95-( ) panel Lamps light up a. Check Cords CO-335 and CO-316 b. Check for discharged battery in Power Unit PE-95-( ) Change lamps Check associated cords and plugs
h. Radio Transmitter BC-610-E
Item No. Item Action or condition Normal indications Corrective measures
START 31 FILAMENT POWER switch Set switch at ON. (Wait 1 minute for filaments to reach operating temperature. Wait 30 minutes if transmitter is damp) a. Green pilot lamp and PLATE TUNING dial on transmitter light b. Red pilot lamp on Speech Amplifier BC-614-E lights c. FIL. VOLTAGE meter reads 5 to 5.3 volts a. If only one lamp lights, replace the other lamp. If both lamps are out, check Fuses FSi, 2, 4, and Cord CD-763. Check that V13, V14, and Vis are firmly seated in their sockets b. Replace lamp if lamps in a above light c. Adjust FILAMENT VOLTAGE control
i. Junction Box JB-70-A
Item No. Item Action or condition Normal indications Corrective measures
START 32 Transmitter control switch a. For c-w transmission, set at TRANS. ON b. For voice transmission, set at TRANS. OFF a. Red pilot lamp on transmitter lights. Plate power relay RYi clicks b. Red pilot lamp is out a. If the relay clicks but the red pilot does not light, check fuse FS3. (See ch. 5) b. See chapter 5
bl
66. Check List (Cont'd)
j. Radio Receivers BC-312-( ) and BC-342-( )
Item No. Item Action or condition Normal indications Corrective measures
START 33 34 OFF-M.V.C.-A.V.C. switch VOL control Turn toM.V.C. or A.V.C. position. (If Radio Receiver BC-312-( ) is used, set Rectifier RA-63-(*) switch at HI CHARGE) Rotate clockwise Dial lights unless dial light switch is provided. If Radio Receiver BC-312-( ) is used, the dynamotor starts Signal or noise is heard. Check panel fuses. Check Cords CD-565 and CD-566 and associated plugs See TM 11-850
k. Radio Transmitter BC-610-E
Item No. Item Action or condition Normal indications Corrective measures
EQUIPMENT PERFORMANCE 35 36 EXCITATION METER SWITCH P.A. PLATE meter Key J-37 held closed or microphone press-to-talk switch operated. EXCITATION METER SWITCH set to— a. DOUBLER PLATE b. INT. AMP. GRID. c. INT. AMP. PLATE. d. P.A. GRID. a. Voice operation; microphone press-to-talk switch operated b. C-w operation; Key J-37 closed a. 25 to 45 ma. b. 1 to 8 ma. c. 125 to 175 ma. d. 60 to 100 ma. a. 200 to 260 ma. b. 200 to 300 ma. a. If the meter does not indicate in any position, check— (1) The installation and tuning of the tuning unit (2) The setting of the BAND SWITCH (3) The position of the M.O.-XTAL switch on the tuning unit b. If the meter readings are improper, retune the transmitter, replace Vs, Vg, Vio, or Vn if necessary Retune transmitter. Check coil unit L7. Operate OVERLOAD RELAY. Check antenna coupling. Replace V6, V7, or Vie if necessary. (See ch. 5)
I. Antenna Tuning Unit BC-939-A
Item No. Item Action or condition Normal indications Corrective measures
EQUIPMENT PERFORMANCE 37 ANTENNA CURRENT meter Key J-37 held closed or microphone press-to-talk switch operated. Operating frequency is— a. 2 to 8 meg. b. 8 to 12 meg. c. 12 to 18 meg. ANTENNA CURRENT meter reads: a. 7 to 14 amp. b. 5 to 12 amp. c. 2% to 10 amp. Check control settings, tuning, coupling, and antenna range switch. (See ch. 5)
68
66. Check List (Cont'd)
m. Speech Amplifier BC-614-E
Item No. Item Action dr condition Normal indications Corrective measures
EQUIPMENT PERFORMANCE 38 MODULATOR PLATE meter Microphone press-to-talk switch operated and— a. With no modulation b. With modulation MODULATOR PLATE meter reads— a. 35 to 50 ma. b. 200 ma on voice peaks a. Check fuse FSs and adjustment of MODULATOR BIAS control b. Check gain control of CARBON MIC. 1 or DYNAMIC MIC. 2, tube V5, and fuse FS5. (See ch. 5)
n. Junction Box J B-70-A
Item No. Item Action or condition Normal indications Corrective measures
EQUIPMENT PERFORMANCE 39 40 Key J-37 (c-w operation) Microphone (voice operation) Key operated Press-to-talk switch operated Sidetone is heard. Relays in junction box and receiver click. P.A. PLATE, EXCITATION, and ANTENNA CURRENT meter needles flick. The receivers are disabled. Meters indicate as in items 35 to 38. Receivers are disabled Check key cord, plug, and jack. (See ch. 5) • Check microphone cord, Amphenol plug and receptacle
o. Receivers BC-312-( ) and BC-342-( )
Item No. Item Action or condition Normal indications Corrective measures
W // 41 VOL control Control rotated clockwise Increased output is heard in the headset or loudspeaker Tighten setscrew. See TM 11-850
Ph Ph 42 Headset or loudspeaker Set operating normally. Plug inserted completely Signal is heard Check plug and cable connections. Tune receiver
Ww 43 ALIGN INPUT control When rotated Response varies See TM 11-850
Ph 44 CRYSTAL PHASING control (when provided) When rotated Response varies Sec TM 11-850
p. Junction Box JB-70-A
Item No. Item Action or condition Normal indications Corrective measures
STOP 45 Transmitter control switch Set to TRANS. OFF Red pilot lamp goes out See chapter 5
69
66. Check List (Cont'd)
q. Radio Transmitter BC-610-E
Item No. Item Action or condition Normal indications Corrective measures
STOP 46 FILAMENT POWER switch Set to OFF a. Green pilot lamp and PLATE TUNING dial lamp go out b. Pilot lamp on Speech Ampli her B C-614-E goes out c. No voltage indication on FIL. VOLTAGE meter See chapter 5
r. Receivers BC-312-( ) and BC-342-( )
Item No. Item Action or condition Normal indications Corrective measures
STOP 47 OFF-M.V.C.-A.V.C. switch Turn to OFF position Receiver turned off See TM 11-850
s. Junction Box JB-70-A
Item No. Item Action or condition Normal indications Corrective measures
STOP 48 STOP button Push red STOP button Power Unit PE-95-( ) stops See chapter 5
t. Rectifier RA-63-(*)
Item No. Item Action or condition Normal indications Corrective measures
STOP 49 Main control switch Set at OFF. Check the battery with the hydrometer 1.265 specific gravity at 70° F • Recharge the battery with Rectifier RA-63-(*). Add distilled or battery-approved water to the battery if insufficient liquid is present to obtain a reading on the hydrometer
CHAP’rER 3
CHAPTER 3
PREVENTIVE MAINTENANCE
Section I. PREVENTIVE MAINTENANCE TECHNIQUES
67. Meaning of Preventive Maintenance
Preventive maintenance is a systematic series of operations performed at regular intervals on equipment, when turned off, to eliminate major break-downs and unwanted interruptions in service, and to keep the equipment operating at top efficiency. To understand what is meant by preventive maintenance it is necessary to distinguish between preventive maintenance, trouble shooting, and repair. The prime function of preventive maintenance is to prevent break-downs and therefore the need for repair. On the other hand, the prime function of trouble shooting is to locate existing defects making repairs possible. The importance of preventive maintenance cannot be overemphasized. The entire system of radio communication depends on each set’s being on the air when it is needed and also upon its operating efficiency. It is vitally important that radio operators and repairmen maintain their radio sets properly.
Note. The operations in sections I and II are considered first and second echelon (organization operators and repairmen) maintenance. Some operations in sections III and V are considered higher echelon maintenance.
68. Description of Maintenance Techniques
a. General. Most of the electrical parts in Radio Sets SCR-399-A and SCR-499-A require routine preventive maintenance. Those requiring maintenance differ in the amount and kind required. Because hit-or-miss maintenance techniques cannot be applied, definite and specific instructions are needed. This section of the manual contains these specific instructions and serves as a guide for personnel assigned to perform the six basic maintenance operations, namely: FEEL, INSPECT, TIGHTEN, CLEAN, ADJUST and LUBRICATE. Throughout this manual the lettering system for the six operations will be as follows:
F—Feel C—Clean
I—Inspect A—Adjust
T—Tighten L—Lubricate
The first two operations establish the need for
the other four. The selection of operations is based on a general knowledge of field needs. For example, the dust encountered on dirt roads during cross-country travel filters into the equipment no matter how much care is taken to prevent it. Rapid changes in weather (such as heavy rain followed by blistering heat) excessive dampness, snow, and ice tend to cause corrosion of exposed surfaces and parts. Without frequent inspections and the necessary performance of tightening, cleaning, and lubricating operations, the equipment will become undependable, and subject to break-down when the equipment is most needed.
6. Feel. The feel operation is used most often to check rotating machinery, such as blower motors, drive motors, etc., and to determine whether electrical connections, bushings, etc., are overheated. Feeling indicates the need for lubrication or the existence of similar types of defects requiring correction. The maintenance man must become familiar with the normal operating temperatures of motors, etc., in order to recognize signs of overheating.
Note. It is important that the feel operation be performed as soon as possible after shut-down and always before any other maintenance is done.
c. Inspect. Inspection is the most important operation in the preventive maintenance program. A careless observer will overlook the evidences of minor troubles. Although these defects may not interfere with the performance of the equipment, valuable time and effort can be saved if they are corrected before they lead to major break-downs. Make every effort to become thoroughly familiar with the indications of normal functioning, in order to be able to recognize the signs of a defective set. Inspection consists of carefully observing all parts of the equipment, noticing their color, placement, state of cleanliness, etc. Inspect for the following conditions:
(1) Overheating, as indicated by discoloration, blistering, or bulging of the parts or surface of the container; leakage of insulating
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compounds; and oxidation of metal contact surfaces.
(2) Placement, by observing that all leads and cables are in their original positions.
(3) Cleanliness, by carefully examining all recesses in the units for accumulation of dust, especially between connecting terminals. Parts, connections, and joints should be free of dust, corrosion, and other foreign matter. In tropical and high-humidity locations, look for fungus growth and mildew.
(4) Tightness, by testing any connection or mounting which appears to be loose.
d. Tighten, Clean, and Adjust. These operations are self-explanatory. Specific procedures to be followed when performing them are given wherever necessary throughout this section.
Caution: Screws, bolts, and nuts should be tightened carefully. Fittings tightened beyond the pressure for which they are designed will be damaged or broken.
Whenever a loose connection is tightened, it should be moistureproofed and fungiproofed again by applying the varnish with a small brush. See section V for details of moistureproofing and fungiproofing.
e. Lubricate. Lubrication refers to the application of grease or oil to the bearings of motors or other rotating shafts. It may also mean the application of a light oil to door hinges or other sliding surfaces on the equipment.
69. Recommended Lubricants
The following table lists the lubricating material necessary in servicing the equipment:
Approved Symbol Standard nomenclature Specification No.
OE 30 Oil, Engine, SAE 30 U. S. Army 2-104B
OE 10 Oil, Engine, SAE 10 U. S. Army 2-104B
PS Oil, Lubricating, Preserva-
tive, Special U. S. Army 2-120
GL Grease, Lubricating, Special Ordnance AXS-637
SD Solvent, Dry-cleaning Federal P-S-661a
70. Vacuum Tubes
Note. Avoid doing work on the tubes immediately after shut-down. Severe burns may result from contact with the envelopes of hot tubes.
a. Inspect (I). (1) Inspect glass and metal tube envelopes, tube caps, and tube connector clips for accumulation of dirt and for corrosion. Tubes with loose plate caps, grid caps, or envelopes should be replaced if possible.
(2) Examine the spring clips that make contact with the grid caps for corrosion and for loss of tension. Check the condition of the wires soldered to the spring clips. The wires should be free from frayed insulation and broken strands.
(3) Inspect the firmness of tubes in their sockets. Make the inspection by pressing the tubes down in the sockets and testing them in that position; not by partially withdrawing the tubes and jiggling them from side to side. Movement of a tube tends to weaken the pins in the base and unnecessarily spread the contacts in the socket. It is desirable to inspect the sockets of the tubes at the time the tubes are removed.
(4) When it is necessary to remove a tube from its socket, especially if it is a high-power
tube, great care must be used. Never jar a warm tube. Connections to the grid caps and plate caps must always be removed.
b. Tighten (T). Tighten all loose connections to the tube sockets or to the tubes. If the connections are dirty or corroded, clean before tightening. When tightening locknuts that hold the sockets to the insulated bushings, do not apply excessive pressure. Too much pressure will crack the bushings.
c. Clean (C). (1) Clean the tubes only if inspection shows cleaning to be necessary. Tubes operated at high voltages and with exposed plate and grid connections must be kept free of dirt and dust because of possible leakage between grid and plate terminals. Tubes operating at low voltages and not having exposed grid and plate caps do not require frequent cleaning. However, do not permit dirt to accumulate on low-voltage tubes.
(2) Remove dust and dirt from the glass or metal envelopes with a clean, lint-free, dry cloth. If proper care is exercised, the grid and plate caps may be cleaned with a piece of #0000 sandpaper. Wrap the paper around the cap and gently run along the surface. Excessive pres
73
sure is not needed; do not grip the cap tightly. Wipe with a clean dry cloth.
(3) When tube sockets are cleaned and the contacts are accessible, fine sandpaper may be used to remove corrosion, oxidation, and dirt.
d. Adjust (A). Adjust loose tube connector clips. Do not flatten tube connector clips during adjustment. Flattened clips do not make adequate contact with the surface of the tube cap. If the clip is made of thin metal, it can be adjusted by gently compressing it with the fingers. If it is made of heavy-gauge metal, suitable pressure can be applied with a pair of long-nose pliers.
71. Capacitors
a. Inspect (I). (1) Inspect the terminals of large fixed capacitors for corrosion, loose connections, cracks, and breakage. Carefully inspect the mountings to discover loose mounting screws, studs, or brackets. Examine the leads for poor insulation, for cracks, and for evidences of decay. Cut away frayed strands on the insulation. If the wire is exposed, wrap it with friction tape.
(2) Inspect the case of each large fixed capacitor for leaks, bulges, and discoloration.
(3) Inspect the plates of variable capacitors for dirt, dust, or lint. Examine the movable set of plates for signs of damage or misalignment that would cause them to touch the fixed plates during tuning. Rotate the movable plates, using the panel tuning control, and thus check for operation of the capacitor.
b. Tighten (T). Tighten loose terminals, mountings, and connections on the capacitors. Do not break the bushing or damage the gasket.
c. Clean (C). (1) Clean the cases of fixed capacitors, the insulating bushings, and connections that are dirty or corroded. The capacitor cases and bushings can usually be cleaned with a dry cloth, but if the deposit of dirt is hard to remove, moisten the cloth in a dry-cleaning solvent.
(2 ) Clean the plates of variable capacitors with a small brush, removing all dust and lint.
72. Resistors
a. Inspect (I). Inspect the coating of the vitreous-enameled resistors for signs of cracks and chipping, especially at the ends. Examine the bodies of all types of resistors for blister
ing, discoloration, and other indications of overheating. Inspect leads and all other connections for corrosion, dirt, dust, looseness, and broken strands in the connecting wires. Check the security of all mountings. Do not attempt to move resistors with pigtail connections, because there is danger of breaking the connections at the point where they enter the body of the resistor. Such defects cannot be repaired.
b. Tighten (T). Tighten resistor connections and mountings whenever they are found loose. If a resistor is allowed to remain loose, vibration may break the connection or damage the body.
c. Clean (C). (1) Clean all carbon resistors with a small brush.
(2 ) Vitreous-enameled resistors must be kept clean to avoid leakage between the terminals. They are ordinarily wiped with a clean dry cloth. However, if the dirt deposit is unusually hard to remove, use a dry-cleaning solvent.
(3 ) Resistors with discolored bodies cannot be cleaned. Discoloration indicates that there has been overloading and overheating at some time prior to the inspection. The discoloration is probably due to circuit trouble which requires analysis and correction. Trouble-shooting procedures are described in chapter 5.
73. Fuses
a. Inspect (I). Inspect the fuse caps for evidence of burning. Any evidence of burning indicates that the fuse contact is not tight. Examine the fuses and holders for signs of corrosion, dirt, loose connections, and loss of spring clip tension.
b. Clean (C). Clean fuse ends and fuse clips with #0000 sandpaper; then wipe them with a clean cloth. If the fuse clips are burned and pitted, use a fine file to dress the clips properly, and finish with emery cloth to leave a smooth surface. Be sure to remove all traces of emery dust because emery dust is a good conductor of electricity and may cause short circuits.
c. Tighten (T). Tighten all loose wire connections to the fuses. Make certain that all connections are clean before tightening.
d. Adjust (A). Adjust the spring tension on the fuse clips if necessary. Use a pair of long-nose pliers for this operation. Do not flatten the clip while adjusting because a flattened clip makes poor contact.
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74. Bushings and Insulators
a. Description. (1) Insulated bushings are used in the high-voltage and r-f circuits. They are constructed of ceramic material with a glazed surface. Because an insulator is no better than its surface, deposits of foreign substances on the surface will materially reduce the insulation value of the bushing. Therefore, it is very important that all bushings used in the high-voltage circuits be inspected frequently.
(2) Insulator bushings are used as supports for high-voltage tube sockets, for high-voltage terminals of capacitors, and for tank coils. They are used as mountings for resistors in high-voltage circuits and as supports for panels which mount other parts. The condition of insulator bushings that are used solely as panel supports is not critical, but the condition of bushings used as high-voltage insulators is extremely important.
b. Inspect (I). Inspect the physical condition of the insulator bushings. They should be clean and free from cracks or chips. It is possible for a highly glazed insulator to develop fine-line surface cracks where moisture and dust will accumulate and eventually form a leakage for a high-voltage flash-over. Consequently, the surface of the bushings must be inspected to detect such cracks. As a rule, the bushings are held in position with nuts screwed onto the threaded conductors. These bushings can be replaced very easily by unscrewing the nuts. If replacement is not possible because of a shortage of supplies, frequently clean the defective bushing thoroughly with dry-cleaning solvent. Sometimes it is difficult to see dust on a glazed surface. A satisfactory check can be made by sliding a clean finger across the bushing.
c. Tighten (T). The procedure to be used in tightening loose bushings is self-evident. However, one precaution must be observed. Do not force the nuts or screws down too fight. Excessive pressure exerted on the bushings will cause damage. If the threads on bushing stud bolts are found stripped so that they cannot be tightened, replace the entire bushing.
d. Clean (C). Insulating bushings are easily cleaned. Never use abrasive materials because the glazed finish will be destroyed. A clean cloth is usually satisfactory. If deposits of grime or dirt on the surface of a bushing are hard to remove, use dry-cleaning solvent. After the sur
face has been cleaned with a solvent, it should be carefully polished with a clean dry cloth. Otherwise, a thin film of the solvent will be left which will impair the effectiveness of the bushing as a high-voltage insulator.
75. Relays
a. General. Relays normally require very little attention. Extreme care should be used during all operations of preventive maintenance; otherwise, these same operations may result in trouble that would not have existed if the relay had not been tampered with.
b. Inspect (I). Inspect the mechanical action of the relays to make certain that when the moving and stationary contacts come together they make positive contact and are directly in line with each other. Inspect the contacts for dust that may result in poor contact or arcing. Do not mistake the brown stain often found on silver contacts for corrosion. This brown stain is silver oxide and is a good conductor.
c. Tighten (T). Tighten all loose connections and mounting screws, but do not apply enough force to damage the screw or to break the parts it holds.
d. Clean (C). Brush the exterior of the relay with a soft brush to remove dust. If inspection shows that the contacts require cleaning, clean them with a strip of white paper placed between the contacts. Close the contacts on the paper just enough to grip the paper snugly, and draw the paper between the contacts. Dry-cleaning solvent may be used on the paper if corrosion is present or if dirt deposits are not readily removed with the dry paper. If the contacts are burned or pitted, they may be dressed down with a fine file followed with a burnishing tool and crocus cloth.
e. Adjust (A). Adjust the contacts of the relays only if they do not close evenly and securely. Too frequent adjustment of the relays usually results in equipment failure.
76. Switches
a. Inspect (I). (1) Inspect the mechanical action of each switch and, while doing so, look for signs of dirt or corrosion on all exposed elements. In some cases, examine the elements of the switch visually; in others, check the action of the switch by flipping the control knob or toggle, or press the switch button and note the
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freedom of movement and the amount of spring tension.
(2) Examine the ganged multiple-section switches to see whether they are properly lubricated and whether the contacts are clean. The inspection is visual. Do not pry the leaves of the switch apart. The rotary members should make good contact with the stationary members; and as the former slides into the latter, a spreading of the stationary contact leaves should be noticeable. The switch action should be free. The wiping action of the contacts usually removes any dirt at the point of contact.
b. Clean (C). With a small brush, clean dust and dirt from all switches. Be very careful while brushing around exposed contacts.
c. Lubricate (L). If necessary, lubricate the bearing surfaces of the multiple-section switches (such as the BAND SWITCH on Radio Transmitter BC—610-E and the antenna band switch on Antenna Tuning Unit BC-939-A). Apply only a thin film of special lubricating preservation oil (PS). Do not permit excess oil to run down onto wires or other parts.
77. Coils
a. Inspect (I). Inspect all coils for dirt, poor connections, and damaged insulation. The coil forms supporting the transmitter coils should be inspected for cracks in the insulation and loose joints in the insulation supporting the coil windings. Examine the pins of the plug-in coils for damaged or defective pins. See that the pins maintain the necessary spring action to insure good contact in the pin sockets.
b. Tighten (T). Tighten all loose connections on coils, after first making certain that the connection is free of dirt or corrosion. Recement loose joints in the insulation supporting the coil windings. Tighten the nuts supporting the pins in plug-in coils, if the pins are found to be loose. Do not exert excessive pressure while tightening these nuts; excessive pressure will crack the supporting insulator.
c. Clean (C). Clean the coil form and coil with a soft brush. Remember that the ceramic coil form is actually performing the function of a high-voltage insulator, hence the same preventive maintenance applies to the coil form as to high-voltage insulators and bushings.
78. Rheostats and Potentiometers
a. INSPECT (I). Inspect all rheostats and po
tentiometers for cleanliness and mechanical action. Potentiometers which are protected with dust covers should be inspected externally only. Do not remove the dust covers. Look for loose connections and loose mounting nuts. Examine the sliding arm of exposed rheostats and potentiometers for firm contact with the resistance element. Look for corrosion on the contact of the sliding arm.
b. Tighten (T). Tighten any loose connections or mounting nuts.
c. Clean (C). Use a soft brush to clean dust and dirt from the exposed resistance elements and sliding arms. Use crocus cloth to remove corrosion from the contact surface of exposed, wire-wound resistance elements, and from the contact surface of the sliding arm of exposed rheostats and potentiometers.
d. Adjust (A). If inspection reveals that the sliding arm is not making adequate contact with the resistance element, increase the spring tension. Any adjustment to the spring tension should be made with extreme caution to avoid damaging the control.
79. Terminal Blocks
a. Inspect (I). Inspect the terminal blocks for cracks, breakage, dirt, and loose connections or mounting screws.
b. Tighten (T). Tighten loose screws, lugs, and mounting bolts. When tightening screws, be sure to select a screw driver of correct size. Do not exert too much pressure.
c. Clean (C). Remove all dust and dirt from the terminal blocks with a small brush. Remove corrosion from connections with #0000 sandpaper.
80. Multiple Connectors
a. Inspect (I). Inspect the exterior of all multiple connectors, male and female, for dust, dirt, corrosion, or damaged pins. Look for traces of moisture on the insulated portion of the connector. Inspect the interior of the connectors for loose connections and broken strands of wire to the various pins. Loose strands should be soldered in place. If the insulation on each wire connected to the pins does not extend entirely to the pin, wrap the bare wire with friction tape to prevent short circuits.
b. Clean (C). Remove all dust and dirt from the exterior and interior of the connectors. Wipe the moisture out with a clean dry cloth. In tropical areas, the insulated portion of the connector
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will mold rapidly if moisture is not removed at frequent intervals. Light mold may be removed by wiping with a clean dry cloth. If mold is excessive, use a cloth dampened with dry-cleaning solvent. Use #0000 sandpaper for removing corrosion from metal parts of the connector.
81. Cords and Cables
a. Inspect (I). Inspect the cables for cracked or deteriorated insulation, frayed or cut insulation at the connecting and supporting points, and improper placement which puts the cables or connections under strain. Watch for kinks which will damage the wires within the cable. Examine for oil or grease on the rubber insulation. Oil or grease causes rapid deterioration of rubber.
b. Tighten (T). Tighten loose cable clamps, coupling rings, and cable connections.
c. Clean (C). Remove all dust, dirt, oil, grease, and foreign matter from all cables and cords. Dirt often hides defects in the cable insulation. These hidden defects may result in equipment failure.
82. Meters
a. Inspect (I). Inspect the connections for loose, dirty, or corroded connections. Look for cracked meter glass. Inspect for loose meter mounting screws.
b. Tighten (T). Tighten all loose connections to the meter. Make certain that connections are clean before they are tightened. Tighten the meter mounting screws if necessary.
c. Clean (C). Clean the entire exterior of the meter with a clean dry cloth. Clean cor-rodded connections with #0000 sandpaper.
d. Adjust (A). Meters normally register zero when the equipment is turned off. Occasionally a meter will become out of adjustment and require adjustment. Before adjusting, however, a test should be made to determine whether the meter has acquired a charge of static electricity as a result of cleaning the meter glass with a dry cloth. Such a static charge will cause a meter movement to register above (or below) zero reading with the equipment shut off. To test the meter for static charge, dampen the fingers of one hand and place the little finger firmly on a screw head or other metal part of the component to place the body at a chassis ground potential. Brush the
dampened thumb slowly across the face of the meter glass. The static charge should drain off, releasing the meter movement so that the meter will register zero. In some cases this discharge is not effected, but the meter needle deflection will vary during the time that the thumb is brushed over the glass if a static charge is present. In this case, allow the meter to remain idle for 5 minutes to allow a natural drain. If the meter movement is not affected in any way by the above test, no static charge is present. To adjust the movement, use a small thin-blade screw driver in the adjustment screw in the lower edge of the meter face. Rotate the screw to the right or left as required to bring the needle to zero.
83. Pilot Lamps
a. Inspect (I). Inspect the pilot lamp assembly for loose lamps, loose mounting screws, and loose, dirty, or corroded connections. If a pilot lamp is found with a loose glass envelope, replace the lamp.
b. Tighten (T). Tighten loose mounting screws and resolder loose connections. If the connections are dirty or corroded, clean before soldering. Tighten loose lamps in their sockets.
84. Jacks
a. Inspect (I). Although jacks require very little attention, inspect them periodically for cleanliness and tightness. Insert the proper plug in the jack and note the action of the jack. Contact to the plug should be secure.
b. Tighten (T). Tighten the mounting nut or screws on all jacks, if they are found to be loose.
c. Clean (C). Clean the jacks thoroughly with a stiff brush. If the contacts on the jacks are corroded, clean them with crocus cloth.
d. Adjust (A). Adjust the spring contact of the jacks only if inspection shows that the jacks are not making firm contact with the plugs. Bend the spring contact with a pair of long-nose pliers. Check the action of the jack with a plug after each adjustment.
85. Dynamotors and Motors
a. Inspect (I). Inspect for dust and dirt around the commutator and brushes. Inspect the brushes for wear and signs of arcing. Check the tension of the brush springs. Look for poor connections at the brushes as well as at the plug.
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b. Feel (F). Feel the bearings as soon as possible after shut-down of the equipment, to determine whether the bearings are running hot. Become accustomed to the amount of heat to expect at the bearings under normal conditions.
c. Tighten (T). Tighten the mounting bolts securing the dynamotor or motor. Tighten any loose connections at the brushes or plugs.
d. Clean (C). Use a dry clean cloth to remove dust and dirt from the exterior of all dynamotors and motors. If heavy dirt deposits are not readily removed, use dry-cleaning solvent on a clean cloth. Use an air stream from an air compressor to blow the dust out of the interior of motors if dry compressed air is available. Use a soft brush to remove the dust if dry compressed air is not available.
e. Lubricate (L). Lubricate the ventilating fan air-control plate screw sparingly with oil. Lubricate the ventilating fan motor bearings and the heater fan motor bearings with oil as follows:
(1 ) Temperatures above -[-32° F. Use engine oil SAE 30 (OE 30).
(2 ) Temperatures from t° 0° F-
Use engine oil SAE 10 (OE 10).
(3 ) Temperatures below 0° F. Use special preservative lubricating oil (PS).
86. Cabinets, Chassis, and Mountings
a. Inspect (I). Inspect all cabinets and chests for cleanliness. Examine all chassis and mountings for loose screws, dirt, and corrosion or rust. Check all panels for loose knobs.
b. Tighten (T). Tighten all loose mounting screws, loose chassis screws and bolts, and all loose knobs or handles. Tighten all wingnuts and turnbuckles which secure the various components to their mountings or the mountings to the shelter.
c. Clean (C). Wipe all dust and dirt from the exterior and interior of the cabinets and chests. Brush out the dust and dirt from the chassis and mountings. Use dry-cleaning solvent on a clean cloth to remove stubborn accumulations of dirt. Use #0000 sandpaper to remove corrosion and rust. Cover all bare spots on metal surfaces with touch-up paint.
d. Lubricate (L). Lubricate the hinges on chests, the threads on turnbuckles, and the threads on wingnuts with a light oil (special preservative lubricating oil (PS)).
87. Headsets, Microphones, Keys, and Loudspeakers
a. Inspect (I). Inspect all external surfaces for dirt and corrosion. See that all cord connections are tight and that plugs and jacks fit together properly. Inspect the key for proper operation.
b. Clean (C). Wipe the dust and dirt from all external surfaces with a clean dry cloth. Use crocus cloth for removing corrosion from the connecting plugs.
c. Lubricate (L). Lubricate all key bearings with light oil (special preservative lubricating oil (PS)), if needed.
88. Couplings and Control Shafts
a. Inspect (I). Inspect couplings and control shafts for tightness and cleanliness. If the setscrews securing the couplings and control shafts are loose, the switches or capacitors connected to the shafts wrill not rotate through the correct arc, and inaccuracy will result.
b. Tighten (T). Tighten all setscrews securing the couplings and control shafts.
c. Lubricate (L). Lubricate bearings of capacitor shafts (front and rear) and tuningcontrol shaft bearings with 1 or 2 drops of oil. For temperatures above 0° F., use engine oil SAE 10 (OE 10). For temperatures below 0° F., use special preservative lubricating oil (PS). Lubricate the following points on Antenna Tuning Unit BC-939-A with special lubricating grease (GL) :
(1) Antenna high-frequency loading coil contact roller shaft.
(2) Antenna coupling adjustment coil contact roller shaft.
(3) Antenna coupling adjustment control bevel pinions.
(4) Antenna high-frequency tuning control bevel pinions.
(5) Antenna low-frequency tuning control bevel pinions.
89. Gears
a. Inspect (I). Inspect the teeth of the gears on the tuning-capacitor drive mechanism for cleanliness and freedom of operation.
b. Clean (C). Remove all dust and dirt with a small brush. If dirt accumulation is great, use a brush dipped in dry-cleaning solvent.
90. Antennas
a. Inspect (I). Inspect antenna mast sec
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tions for cleanliness and tightness of joints. Examine antenna insulators for cracks, chips, and dirt. Examine antenna lead-in wires for poor connection, kinks, frayed insulation, and dirty connections.
b. Tighten (T). Tighten all mounting bolts supporting the antenna mounting bracket. Tighten loose antenna mast sections.
c. Clean (C). Wipe all dust and dirt from the antenna mast sections and insulators with a clean dry cloth. If dirt accumulations are difficult to remove, use dry-cleaning solvent on the cloth. If dry-cleaning solvent is used as a cleaning agent, wipe the antenna insulators with a clean dry cloth. Use #0000 sandpaper to remove corrosion from antenna connections. Use #0000 sandpaper to remove corrosion or rust spots on the antenna mast sections. Cover any bare metal spots with touch-up paint.
91. Reels
a. Inspect (I), Inspect reels for dirt, rust,
and corrosion. Check to see that the reel operates freely.
b. Clean (C). Remove all dirt from reels with a stiff brush. If rust or corrosion is present, use #0000 sandpaper to remove these spots. Repaint, if necessary, with touch-up paint.
c. Lubricate (L). Lubricate the bearings of the fixed handle of reel hand Axle RL-27, by applying lubricant liberally at the opening between the shaft and the inner end of the handle. To lubricate the handle bearings and lock, remove the handle, clean the lock and flush out the bearings, then relubricate. Clean dirt from the handle shaft before replacing the handle. The correct lubricants to use are:
(1) Temperatures above -\-S2° F. Use engine oilSAE 30 (OE 30).
(2) Temperatures from -j-32° F., to 0° F. Use engine oil SAE 10 (OE 10).
(3) Temperatures below 0° F. Use special preservative lubricating oil (PS).
Section II. ITEMIZED PREVENTIVE MAINTENANCE
92. General
For ease and efficiency of performance, it is suggested that preventive maintenance on Radio Sets SCR-399-A and SCR-499-A be broken down into operations that can be performed at different time intervals. In this section the preventive maintenance work to be performed on the radio set at specified time intervals is broken down into units of work called items. The general techniques involved and the application of the FITCAL operations in performing preventive maintenance on individual parts are discussed in section I. These general instructions are not repeated in this section. When performing preventive maintenance, see section I if more information is required for the following items. All work is to be performed with the power removed from the equipment. After preventive maintenance has been performed, the equipment should be put into operation and checked for satisfactory performance. (See check list, par. 66.)
93. Common Materials Needed
The following materials will be needed in performing preventive maintenance:
Common hand tools (TE-41 or equivalent)
Clean cloth
#0000 sandpaper
Crocus cloth
Fine file or relay burnishing tool Dry-cleaning solvent (SD) Small soft brush
Small stiff brush
Small inspection mirror
Note. Leaded gasoline will not be recommended as a cleaning fluid for any purpose. Dry-cleaning solvent (SD), a cleaning fluid, is available through established supply channels. Oil, Fuel, Diesel, U. S. Army Specification 2-102B, may be used for cleaning purposes when dry-cleaning solvent is not at hand. Since unleaded gasoline is available only in limited quantities, and only in certain locations, it should be used for cleaning purposes only when no other agent is suitable. Carbon tetrachloride, or fire-extinguishing liquid (carbon tetrachloride base), may be used if necessary, but only on contact parts of electronic equipment.
94. Item I. Exterior of Radio Sets SCR-399-A and SCR-499-A
OPERATIONS
I T C L Cabinets and mountings
I T C Control knobs
I T Pilot lamps
REMARKS: Maintenance operations in item 1 do not require the removal of the chassis from their cabinets. Pilot lamp connections inside the cabinets will be handled with items 7 and 9.
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95. Item 2. Headsets, Microphones, Keys, and Loudspeakers
OPERATIONS
IC Headsets
IC Microphones
I C L Keys
IC Loudspeakers
REMARKS: Check connecting cords for breaks
under the insulation. Adjust keys after per-
forming preventive maintenance.
96. Item 3. Cords, Cables, and Connectors OPERATIONS
I T C Cords and cables
I T C Multiple connectors
REMARKS: Perform operations on external surfaces only for multiple connectors. Internal operations will be handled with items 6, 9, and 10.
97. Item 4. Antennas
OPERATIONS
I T C Antenna mast sections
I C Antenna insulator
I T C Mounting bracket
I T C Antenna lead-in
REMARKS: When equipment is used in vehicles, check the tie-down ropes and insulators for security.
98. Item 5. Accessories
OPERATIONS
I C L Reels
I C Shelter H0-17-A
I T C L Chests
REMARKS: Keep all cords and cables off the floor. The shelter must be kept clean and orderly. Keep instruction books in their proper compartment when not in use.
99. Item 6. Interior of Radio Sets SCR-399-A and SCR-499-A
OPERATIONS
I T C Chassis of each main component
I T L Couplings and control shafts
IC Gears
I T C Multiple connectors
REMARKS: Disassemble multiple connectors and check for poor connections, frayed insulation, and broken strands of wire. Do not attempt to remove individual pins within the connector.
100. Item 7. Radio Transmitter BC-6I0-E
OPERATIONS
I T C A Vacuum tubes
I T C Capacitors
I T C Resistors
I T C A Fuses
I T C Bushings and insulators
I T C A Relays
I C L Switches
I T C Coils
I T C A Rheostats and potentiometers
I T C Terminal blocks
I T C A Meters
I T Pilot lamps
REMARKS: Test the transmitter after performing preventive maintenance to be sure that all circuits are correct.
101. Item 8. Antenna Tuning Unit BC-939-A
OPERATIONS
I T C Capacitors
I T C Coils
I T C Bushings and insulators
I C L Switches
IC Gears
I T L Couplings and control shafts
REMARKS: Test for performance after completing preventive maintenance.
102. Item 9. Speech Amplifier BC-6I4-E
OPERATIONS
I T C A Vacuum tubes
I T C Capacitors
I T C Resistors
I T C Bushings and insulators
I T C A Potentiometers
I T C Terminal blocks
I T C A Meter
I T Pilot lamp
I T C A Jacks
I T C Multiple connectors
103. Item 10. Junction Box JB-70-A
OPERATIONS
ITC Capacitors
ITC Resistors
ITC Terminal blocks
ITC A Jacks
ICL Switches
ITC Multiple connectors
80
REMARKS: Use great care when handling the junction box when the chassis is out of its cabinet. The socket insulators break easily if the chassis is not handled properly.
104. Item I I. Rectifier RA-63-)*)
OPERATIONS
I T C A Relay
I T C Terminal block
I C L Switch
REMARKS: Wipe dust, dirt, and moisture from the rectifier unit with a clean dry cloth. Tighten the mounting screws.
105. Item 12. Heating and Ventilating System OPERATIONS
F I T C L Motors
IC Switches
REMARKS: Examine the heating element for loose or corroded connections. Clean dust from the heating coil with a soft brush. Do not allow any inflammable material to come in contact with the heating coil.
106. Item 13. Auxiliary Batteries OPERATIONS
I C Storage batteries
ICT Battery connections
REMARKS: Test the specific gravity of the storage batteries in accordance with TM 11-430.
107. Preventive Maintenance Check List
a. General. The following check list is a summary of the preventive maintenance to be performed on Radio Sets SCR-399-A and SCR-499-A. Some items require preventive maintenance more frequently than others. For this reason the check list divides the preventive maintenance items into daily, weekly, and monthly tasks. This recommended frequency of operation may be varied at the discretion of the commanding officer. Similarly, the check list indicates the echelon most fitted to perform the various tasks. The echelon performing any given item may be changed at the discretion of the commanding officer.
b. Check List
Item No. Operations Item When performed Echelon
Before operation After operation Daily Weekly Monthly
1 2 3 4 5 6 7 8 9 10 11 12 13 1 T C L 1 C L I T C I T C I T C L I T C L I T C A L I T C L I T C A I T C A L I T C A L F I T C L I T C Exterior of Radio Sets SCR-399-A and SCR-499-A Headsets, microphones, keys, and loudspeakers Cords, cables, and connectors Antennas A c cess on es Interior of Radio Sets SCR-399-A and SCR-499-A Radio Transmitter BC-610-E Antenna Tuning Unit BC-939-A Speech Amplifier BC-614-E Junction Box JB-70-A Rectifier RA-63-(*) Heating and ventilating system Auxiliary batteries X X X X 1st 1st 1st 1st 1st 2d 2d 2d 2d 2d 2d 2d 1st
Feel Inspect Tighten
C Clean
L Lubricate
Section III. LUBRICATION
Note. Lubrication orders are not required for Radio Sets SCR—399—A and SCR—499—A. All lubrication instructions on the equipment are included in section I.
Section IV. SPECIAL TOOLS
108. Relay and Commutator Tools
A number of items in preventive maintenance require work of a special and somewhat delicate nature. These include cleaning silver-plated relay contacts, removing pitted surfaces from contacts, polishing and dressing commutators
and slip-rings, and dressing motor and generator brushes. To do the work properly, special supplies and a few specially constructed tools are needed. Most of the required materials are furnished with the radio set, but a few must be improvised.
81
109. Construction of Special Relay and Commutator Tools
Crocus-cloth, canvas, and sandpaper sticks are constructed in the following manner:
a. Obtain one length of wood (or suitable substitute) 1/32 inch thick, % inch wide, and 3% inches long; and three lengths of wood (or suitable substitute) 14 inch thick, 1 inch wide, and 8 inches long. Cut two pieces of crocus cloth, one piece 1 inch wide and 2i/2 inches long, and the other 1 inch wide and 5*4 inches long. Cut one piece of #0000 sandpaper and one piece of canvas, each 1 inch wide and 5© inches long.
b. Cement the small piece of crocus cloth to the small stick, as shown in figure 31 (A). Note that both sides of the stick are covered. Place the stick in the vise until the cement hardens. The pieces of crocus cloth which extend over the edge of the stick may be cut off with a knife. The finished product is shown in figure 31 (A).
c. The long, narrow pieces of crocus cloth, sandpaper, and canvas are cemented to the three long sticks, as shown in figure 31(B). Note that in this case, the fold is over one end of the stick rather than over the side. Again the vise should be used to hold the cover material flat on the stick until the cement has hardened. This finished product is shown in figure 31(B).
I 10. Safety Shorting Stick and Jumper Wires It will be necessary for the maintenance personnel to construct a safety shorting stick and several jumper wires. The suggested method of construction is as follows:
a. Secure a dry piece of wood or some other material which is a good electrical insulator. It should be about 15 inches long and about 1
inch square. The latter dimension is not very important. Securely fasten a piece of copper or brass rod (or thin tubing) to one end of the stick in such a manner that the rod extends 12 inches beyond the end of the stick. The free end of the rod should be bent in the form of a small hook. Solder a piece of heavy flexible hook-up wire about 18 inches long to the metal rod at the point where it is fastened to the stick. Attach a heavy clip to the free end of the wire.
b. The jumper wires are made from heavy flexible wire, about 18 inches long, with heavy clips attached to each end. These are intended for use as shorting links across high-voltage capacitors in components that are being repaired or cleaned.
Section V. MOISTUREPROOFING AND FUNGIPROOFING
III. General
The operation of Signal Corps equipment in tropical areas where temperature and relative humidity are extremely high requires special attention. The following items represent problems which may be encountered in operation:
a. Resistors, capacitors, coils, chokes, transformer windings, etc., fail.
b. Electrolytic action takes place in resistors,
coils, chokes, transformer windings, etc., causing eventual break-down.
c. Hook-up wire and cable insulation breakdown. Fungus growth accelerates deterioration.
d. Moisture forms electrical leakage paths on terminal boards and insulating strips, causing flash-overs and crosstalk.
e. Moisture provides leakage paths between battery terminals.
p,x- y t ®
(J %
CROCUS CLOTH
-------w-------->1 AO,,LESS
F
GLUE HERE / CROCUS CLOTH
END VIEW-I J
GLUE HERE
'--------8’------------ @
2*/2'->
~~1 SUITABLE
________________X f WIDTH
a. SANDPAPER OR GLUE HERE-^y^-A/F CROCUS CLOTH
I J© ,/r
GLUE HERE-%©--^^^ TL327OI
Figure 31. Relay and commutator tools, method of construction.
82
I 12. Treatment
A moistureproofing and fungiproofing treatment has been devised which if properly applied provides a reasonable degree of protection against fungus growth, insects, corrosion, salt spray, and moisture. The treatment involves the use of a moisture- and fungi-resistant varnish applied with a spray gun or brush. See TB SIG 13, Moistureproofing and Fungiproofing Signal Corps Equipment, for a detailed description of the varnish-spray method of moistureproofing and fungiproofing and the supplies and equipment required in this treatment.
Caution: Varnish spray may have toxic effects if inhaled. To avoid inhaling spray, use respirator if available; otherwise, fasten cheesecloth or other cloth material over nose and mouth.
I 13. Sfep-by-Step Instructions for Treating Radio Transmitter BC-610-E
a. Preparation. Make all repairs and adjustments necessary for the proper operation of the equipment.
b. Disassembly. (1) Remove seven screws holding cover plate to back of the set; remove plate.
(2) Tilt the set forward, or place it on its face. Be careful not to rest it on any of the projecting dials or knobs on the front panel.
(3) Remove resistor R19 from its socket. This resistor is not to be treated.
(4) Remove Tubes VT-218 from sockets V3 and V4. These tubes are not to be treated.
(5) Remove capacitor C28 from its contact clips. This capacitor is not to be treated.
(6) Remove antenna coil unit. Antenna coils are not to be treated.
(7) Remove crystals from tuning units. Do not treat crystals.
(8) Clean all dirt, dust, rust, fungus, oil, grease, etc., from the equipment to be processed.
c. Masking. Cover the following .components with masking tape as shown in figures 32, 33, 34, 35, and 36.
(1) Interlock switch SW5, item A, figure 32.
(2) Contacts on socket SO6, item B, figure 32.
Figure 32. Radio Transmitter BC-610-E—rear interior view of chassis, showing method of masking.
Jf A L-
G
B
83
Figure 33. Radio Transmitter BC-610-E—rear interior view of chassis, showing method of masking.
(3) Socket of resistor R19, item C, figure 32.
(4) Variable resistor R12, item D, figure 32.
(5) Tube socket V4, item E, figure 32.
(6) Contacts on four leads to Tubes VT-218, item F, figure 32.
(7) Relay RY3, item G, figure 32.
(8) Contacts of push-button switch SW12, item A, figure 33.
(9) Variable resistor R18, item B, figure 33.
(10) Tube socket V3, item C, figure 33.
(11) Sliding contact area of variable resistor Rn, item D, figure 33.
(12) Audio socket SO5, item E, figure 33.
(13) Wafers of BAND CHANGE switch, item A, figure 34.
(14) EXCITATION METER switch SW8, item B, figure 34.
(15) Underside of jacks which receive antenna coil, item C, figure 34.
(16) Relay RY4, item D, figure 34.
Figure 3L Radio Transmitter BC-610-E—bottom interior view of r-f chassis, showing method of masking.
D '
/
E '
__A - , ~_____b ____ c
A B c D
84
Figure 35. Radio Transmitter BC-610-E—top interior view of r-f chassis, showing method of masking.
of a number of electric lamps placed inside the cabinet. It is recommended that treatment be carried out immediately after a long period of operation.
e. Varnishing. (1) Spray three coats of moistureproofing and fungiproofing varnish (Lacquer, Fungus-resistant, Spec. No. 71-2202 (Stock No. 6G1005.3), or equal) on all components of all three chassis on the transmitter rack, allowing a 15- to 20-minute drying period after each coat.
(2) Using a brush, apply the varnish to those components not reached by the spray. Make sure that all components are adequately protected by varnish.
f. Reassembly. (1) After the varnish is dry, remove the masking tape from all components.
(2) Reassemble by following instructions for disassembly in reverse order.
(3) Test the operation of the transmitter.
g. Marking. Mark the transmitter with “MFP” and the date of treatment.
Example: MFP—27 September 1944.
(17) Jacks which receive antenna coil, item A, figure 35.
(18) Interlock switch, item B, figure 35.
(19) Plates of variable capacitor Ci2 and clip contacts of capacitor C28, item C, figure 35.
(20) Drive gears of capacitor Ci2, item D, figure 35.
(21) Interlock switch, item A, figure 36.
(22) Tuning unit crystal sockets, item B, figure 36.
d. Drying. (1) Place the transmitter in a baking oven, and bake approximately 2 to 3 hours at 160° F.
Caution: Do not exceed 160° F. If wax should begin to melt in any of the components, decrease the temperature and increase the baking time approximately 1 hour for each decrease of 10° F., in temperature.
(2) If a suitable oven for drying is not available, Radio Transmitter BC-610-E may be dried by using a truck as a bake oven, by means of infrared lamps, or in an emergency, by use
Figure 36. Radio Transmitter BC-610-E—top interior view of exciter stages, showing method of masking.
85
I 14. Step-by-Sfep Instructions for Treating Speech Amplifier BC-6I4-E
a. Preparation. Make all repairs and adjustments necessary for the proper operation of the equipment.
b. Disassembly. (1) Loosen four fasteners
lustration, d. Drying. Place the speech amplifier in a baking oven and bake approximately 2 to 3 hours at 160° F.
Caution: Do not exceed 160° F. If wax should begin to melt in any of the components, decrease the temperature and increase the baking
Figure 37. Speech Amplifier BC-61A-E—front panel, showing method of masking.
and remove speech amplifier from its case.
(2) Clean all dirt, dust, rust, fungus, oil, grease, etc., from the equipment to be processed.
c. Masking. Cover the following components with masking tape as shown in figures 37 and 38.
(1) Socket SO1O3 on front panel, item A, figure 37.
(2) Two microphone jacks on front panel, item B, figure 37.
(3) KEY jack on front panel, item C, figure 37.
(4) Socket SO1O2 on front panel, item D, figure 37.
(5) Lamp socket LM101, item A, figure 38.
(6) Key jack J101, item B, figure 38.
(7) Contacts of jacks J]02 (not shown in il
time approximately 1 hour for each decrease of 10° F., in temperature.
e. Varnishing. (1) Spray three coats of moistureproofing and fungiproofing varnish (Lacquer, Fungus-resistant, Spec. No. 71-2202 (Stock No. 6G1005.3), or equal) on all components, allowing a 15- to 20-minute drying period after each coat.
(2) Using a brush, apply the varnish to those components not reached by the spray. Make sure that all components are adequately protected by varnish.
f. Reassembly. (1) After the varnish is dry, remove the masking tape from all components.
(2) Reassemble by following the instructions for disassembly in reverse order.
A
C
D
O
86
Figure 38. Speech Amplifier BC-6H-E—bottom
interior vieto of chassis, showing method of masking.
(3) Test the operations of the speech amplifier.
g. Marking. Mark the speech amplifier with “MFP” and the date of treatment.
Example: MFP—27 September 1944.
I 15. S+ep-by-Step Instructions for Treating Junction Box JB-70-A
a. Preparation. Make all repairs and adjustments necessary for the proper operation of the equipment.
b. Disassembly. (1) Loosen four fasteners and remove junction box from its case. Disconnect the four wires attached to the terminal strip on the inside rear of the junction box.
(2) Clean all dirt, dust, rust, fungus, oil, grease, etc., from the equipment to be processed.
c. Masking. Cover the following components with masking tape as shown in figures 39 and 40.
(1) Holes in case of receiver output switch SW204, item A, figure 39.
(2) Contacts of wafer switch SW205, item B, figure 39.
(3) Three jacks J20i, J204, and J2n5, item C, figure 39.
(4) Contacts of push-button switch SW20c>, item D, figure 39.
(5) Contacts of transmitter receiver switch SW203, item E, figure 39.
(6) Three jacks J200, J202, and J203, item F, figure 39.
(7) Holes in case of receiver disabling switch SW 201, item G, figure 39.
(8) Contacts of wafer selector switch SW202, item H, figure 39.
(9) Holes in case of receiver disabling switch SW200, item I, figure 39.
(10) Socket SO205 on side of chassis, item A, figure 40.
(11) Socket SO209 on side of chassis, item B, figure 40.
(12) Six jacks on front panel, item C, figure 40.
(13) Twelve sockets on bottom of chassis, item D, figure 40.
(14) Two terminal posts on front panel, item E, figure 40.
TL14157.
87
■.;.............. ■ _____ TL 14158
Figure 39. Junction Box JB-70-A—top interior view of chassis, showing method of masking.
d. Drying. Place the junction box in a baking oven and bake approximately 2 to 3 hours at 160° F.
Caution: Do not exceed 160° F. If wax should begin to melt in any of the components, decrease the temperature and increase the baking time approximately 1 hour for each decrease of 10° F., in temperature.
e. Varnishing. (1) Spray three coats of moistureproofing and fungiproofing varnish (Lacquer, Fungus-resistant, Spec. No. 71-2202 (Stock No. 6G1005.3), or equal) on all components, allowing a 15- to 20-minute drying period after each coat.
(2) Using a brush, apply the varnish to those components not reached by the spray. Make
sure that all components are adequately protected by varnish.
f. Reassembly (1) After the varnish is dry, remove the masking tape from all components.
(2) Reassemble by following the instructions for disassembly in reverse order.
(3) Test the operation of the junction box.
g. Marking. Mark the junction box with “MFP” and the date of the treatment.
Example: MFP—27 September 1944.
I 16. Instructions for Treating Radio Receivers BC-3 12—( ) and BC-342-( )
For instructions for moistureproofing and fungiproofing Radio Receivers BC-312-( ) and BC-342-( ) see C 1, TM 11-850.
ABC DEF G H |
88
Figure Jf.0. Junction Box JB—70—A—bottom view of chassis and front panel, showing method of masking.
B
A \
« .. v
G
D
E
chapter 4
JSXBJ®
CHAPTER 4
AUXILIARY EQUIPMENT
Section I. FREQUENCY CONVERSION KIT MC-509
I 17. Description
a. Frequency Conversion Kit MC-509 is used to extend the transmitter frequency range of Radio Sets SCR-399-A and SCR-499-A to cover the additional range of 1.0 to 2.0 me.
b. The component parts of Frequency Conversion Kit MC-509 are:
1 Chest CH-251
3 Tuning Units TU-61 (range 1.5 to 2.0 me)
3 Tuning Units TU-62 (range 1.0 to 1.5 me)
2 Coil Units C-454 (range 1.5 to 2.0 me)
2 Coil Units C-455 (range 1.0 to 1.5 me) 2 vacuum capacitors, 100-mmf
2 vacuum capacitors, 50-mmf
1 Antenna AN-168, long wire
7 Mast Sections MS-44
1 Mast Base MP-19
2 Guy Plates MP-20
6 Stakes GP-2
1 Guy GY-24-A (halyard)
4 Guys GY-22-A (2 in use, 2 spares)
1 Roll BG-176, antenna
1 BagBG-102-( ) antenna accessories
1 Wire W-128, 2-foot
1 bag of hardware, including:
1 lug, solder (with %-inch hole)
1 lug, solder (with 8-32 machinescrew hole)
1 screw, machine, 8-32 x 1% inches long
1 lockwasher, 8-32
1 nut, hexagonal, 8-32
I 18. Installation on Antenna Tuning Unit BC-939-A
Antenna Tuning Unit BC-939-A may be modified by the use of Frequency Conversion Kit MC-509 to allow operation of Radio Sets SCR-399-A and SCR-499-A on frequencies from 1.0 to 2.0 me. To install, refer to figure 41 and proceed as follows:
TO MAST BASE MP-47-1 )--J
2-IOMC /
I Pl!I y6 r----------------X/ °
I <—> °--------1
| 1 Y, ( ' k | _
। --------pX
f i'I;/ I <--> -^VACUUM^r
I ' ~l <-----' CAPACITOR \ 7
i u. [ 1 <—>
i < I II
1 § | ; <—;
I UJ I 1 Y
1 > |------- 2-10
। g ।____________Sa sw/9 1
1 * I I X / °~| r-4—
f I._______ xJ r=t^->
TO BC- \ ° / ’ ,__>
610-C ) 1---1 \ ADD THIS / _____)
I__ \ WIRE / <
; Y / (—;
(--— F I 1 2 / ---H L44
P ^Pl-3 Epp x x—x x x x l
--- L5 [ M4 | antenna current
— METER
| TL 13803
Figure 41. Modification of Antenna Tuning Unit BC-939-A.
a. Open the coaxial line inside Antenna Tuning Unit BC-939-A by removing the center conductor of the coaxial line from point Y. Bend this wire away from the insulator, and tape. Attach one end of a 17-inch length of Wire W-128 to point Y.
b. Remove the lead running from coupling coil L5 to the ANTENNA CURRENT meter M4 at terminal 1.
c. Attach the free end of the 17-inch length of Wire W-128 to the ANTENNA CURRENT Meter M4 at terminal 1.
d. Remove the lead from the high-frequency inductor coil L44 to the ANTENNA CURRENT meter M4 at terminal 2. Do not remove the other lead on this same post which runs to a contact of switch SW9tl.
91
92
e. Place the antenna range switch of An- results, select a location away from power lines,
tenna Tuning Unit BC-939-A in the 2-10MC tall trees, or other obstructions. However, neces-
position. sity for cover will not always permit selection
of the best location. In any case, use the best
I 19. Erection and Installation of Antenna Mast compromise between cover and a clear antenna. The choice of location for the erection of the a. Refer to the table of approximate dial antenna is largely dependent upon tactical con- settings (table VI) and determine whether to siderations. (See par. 26.) For best operating use the 125-foot or the 75-foot antenna. Add
MAST BASE MP-47-( ) / \\ \ / / \
MOUNTED ON ROOF OF SHELTER / \\ \ / / \
AND CONNECTING ANTENNA TO ANTENNA / \\ \ / cJ \
TUNING UNIT BC-939-A / ' \ O / it \
/ \ Jk / / '
/ block---. nn / //
O---------------------“-------------------------------------------center ring
GUY GY-24-A_______ J® I) <§1 (A
. (HALYARD)
GROUND DISTANCE \ _____// ____________\ /
' ---------------------- 120 FT. \\ // \ /
GUYING DETAIL
FOR FREQUENCIES 1.0-15 MC, USE 125 FT
FOR FREQUENCIES 1.5-20 MC. USE 75 FT ZGUY PLATE MP-20
/\
\ INSULATORS^ / \ \
—----,N 86 / \ \
MAST BASE MP-47-( ) / \ \
(SEE ABOVE) nb / \ \
/ 1 7 MAST \ \ SECTIONS \
V* / \ MS 44 \
gLTER / I - \ 35FT
/ GUY GY-24 A —J \
A------------------1 GUY GY- 2 2 A — -A
/ GUY PLATE \
/ MP-20 \
/ \
ScpK? । MAST BASE
-----------------------------------------------------------------------------------------------------------------'WWiW*------------------------------------------ 20 F T---------------------------------------------------------------------------------------------------------------Tt । p3O8A
MAST DETAIL
Figure 42. Installation of antenna.
93
a few feet to this length when locating the mast.
b. Erect the mast as directed in paragraph 125cZ(2) through (7), (9), (10), and (11). However, since 1 Guy Plate MP-20 and 4 Guys GY-41-A are not used in this installation, note the following exceptions:
(1) In paragraph 125cZ(2) omit 4 Guys GY-41-A, and use only two Guy Plates MP-20 instead of three.
(2) In paragraph 125(Z (5) omit reference to Guy Plate MP-20 at the junction of the fourth and fifth sections.
c. All necessary items for installation of the antenna mast are provided in Frequency Conversion Kit MC—509. If the %-inch screw originally supplied in Mast Base MP-47-A is no longer available, use Mast Section MS-53.
120. Modification of Radio Transmitter BC-6I0-E
a. Unsolder one end of the 700-ohm, 20-watt resistor R9 which is located adjacent to r-f choke CH4 on the under side of the p-a tank capacitor bakelite mounting panel.
Caution: Failure to do so before operating the transmitter may result in damage to the 700-ohm resistor R9 and r-f choke CH4.
b. To operate on the higher frequency, re
solder the open connection of resistor R9.
121. Operation of Radio Sets SCR-399-A and SCR-499-A in Frequency Range of 1.0 to 2.0 MC.
To operate Radio Sets SCR-399-A and SCR-499-A in the frequency range of 1.0 to 2.0 me, proceed as follows:
a. From the table of approximate dial settings (table VI), determine the correct antenna length for the selected frequency. If a 125-foot antenna is required, connect a short jumper wire around the insulator separating the 75-foot and the 50-foot lengths of antenna wire. (See fig. 42.) If a 75-foot antenna is required, omit this jumper wire.
b. From the table of approximate dial settings (table VI), determine the correct tuning unit, coil unit, and p-a fixed vacuum capacitor to be used for the desired frequency. Install these units in the radio transmitter.
c. The exciter stages are tuned by the M.O., DOUB, and INT AMP controls on the tuning units. See paragraph 47 for procedure to be followed in tuning the exciter stages.
d. To tune the final amplifier stage and adjust the antenna circuit with the p-a amplifier, proceed as follows:
Table VI. Approximate dial settings using antenna tuning unit BC-939—A
Frequency (me) Tuning unit Transmitter Antenna tuning crank 2-10MC Antenna length (ft)
Tuning Unit M.O. DOUB INT AMP Coil Unit PLATE TUNING dial Vacuum capacitor (mmf)
1.0 TU-62 4 3.3 1.5 C-455 33 100 13 125
1.1 TU-62 34 4.7 3.0 C-455 78 100 20 125
1.2 TU-62 54 6.2 5.0 C-455 37 50 28.8 125
1.3 TU-62 69 7.4 6.9 C-455 63 50 33.6 125
1.4 TU-62 80 8.5 7.8 C-455 86 50 38.3 125
1.5 TU-62 90 10.0 9.0 C-455 20 0 44.2 125
1 .5 TU-61 12 3.2 2.2 C-454 54 50 26 75
1.6 TU-61 32 4.6 4.3 C-454 74 50 29.7 75
1.7 TU-61 49 5.7 5.2 C-454 9 0 33.2 75
1.8 TU-61 63 6.7 6.2 C-454 22 0 36.3 75
1.9 TU-61 75 7.3 7.1 C-454 33 0 39.6 75
2.0 TU-61 85 8.2 8.0 C-454 42 0 42.1 75
(1) Refer to the table of approximate dial settings (table VI) for approximate setting of the PLATE TUNING dial and the 2-10MC antenna tuning crank on Antenna Tuning Unit BC-939-A.
(2) Throw the HIGH VOLTAGE PROTECT switch to HIGH VOLTAGE PROTECT.
Caution: Be sure that plate power is turned off when making coupling adjustments.
(3) Set the movable coupling link located in the tank coil (Coil Unit C-454 or C-455) at minimum coupling. Minimum coupling is obtained when the movable coil is at right angles to the tank coil.
(4) Set the transmitter control switch on the Junction Box JB-70-A to the TRANS. ON position.
(5) Place the antenna range switch of An
94
tenna Tuning Unit BC-939-A in the 2-10MC position.
(6) Depress the sending key and adjust the PLATE TUNING dial until the P.A. PLATE meter dips to minimum.
Note. P-a tuning may differ by several divisions from the tuning charts when a vacuum capacitor is inserted across the p-a tank capacitor because of the production tolerances in manufacture of these capacitors. Precautions should be taken to see that the p-a plate current is at the minimum dip when tuning the PLATE TUNING wheel.
(7) Turn the 2-10MC antenna tuning crank to the approximate position indicated in table VI for the desired frequency. As this setting is approached, observe the P.A. PLATE meter for a rising plate current indication. Adjust the crank for maximum current as indicated by the P.A. PLATE meter.
(8) If the current indicated on the P.A. PLATE meter exceeds 110 ma, the coupling is too close and should be decreased. If the meter indicates less than 110 me, the coupling should be increased. After the coupling has been reset, readjust the PLATE TUNING dial for minimum reading of the PLATE CURRENT meter.
(9) Repeat the steps in (6), (7), and (8) above until maximum antenna current is obtained.
Note. Keep in mind the 110-ma maximum allowable P.A. PLATE meter reading.
(10) Throw the HIGH VOLTAGE PROTECT switch to NORMAL. The P.A. PLATE meter should read approximately 290 ma.
(11) Carefully repeat the steps in (6), (7), and (8) above with the HIGH VOLTAGE PROTECT switch in the NORMAL position, and adjust for a reading of 290 ma on the P.A. PLATE meter. The transmitter is now ready for c-w operation. For voice operation proceed as above and then refer to paragraph 49.
122. Theory of Equipment
a. General. To extend the frequency range of Radio Transmitter BC-610-E from 2.0 to 1.0 me, three factors are involved:
(1) A means must be provided for tuning the oscillator, buffer-doubler, and i-p-a stages over the range of 2.0 to 1.0 me.
(2) The p-a tank circuit must be provided with increased inductance and capacitance to tune over the required frequency range.
(3) The antenna must operate efficiently on frequencies from 1.0 to 2.0 me, and a means must be provided for coupling the antenna to the p-a tank circuit.
(4) The function of the electrical components of Frequency Conversion Kit MC-509, which make possible the extended frequency range of Radio Transmitter BC-610-E, is discussed in b, c, and d below.
b. Tuning Units TU-61 and TU-62. The tuning circuits for the oscillator, buffer-doubler, and i-p-a stages of the transmitter are included in plug-in tuning units. Tuning Unit TU-61 covers a frequency range of 2.0 to 1.5 me, and Tuning Unit TU-62 covers a frequency range of 1.5 to 1.0 me. The electrical parts of these tuning units perform the same functions as the electrical parts of Tuning Units TU-47 to TU-54. See chapter 5 for the functioning of these parts.
c. Coil Unit C-454 or C-455 and Vacuum Capacitors. The p-a plate circuit of the transmitter is tuned over a frequency range of 1.0 to 2.0 me by the use of a proper combination of Coil Unit C-454 or C-455 and vacuum capacitors of 50 mmf (micromicrofarads) or 100 mmf respectively. (See table VI.) Coil Units C-454 and C-455 are provided with variable coupling links. By varying the position of the coupling link relative to the p-a tank coil, the operator can secure the required plate power input when loading the transmitter with the antenna.
d. Antenna System. To secure efficient operation of the transmitter on frequencies from 1.0 to 2.0 me, a long wire antenna is used. The antenna operates as a grounded quarter-wave antenna. For frequencies from 1.0 to 1.5 me the physical length of the antenna is 125 feet, and for frequencies from 1.5 to 2.0 me the physical length is 75 feet. Electrically, these antennas are much shorter than a quarter-wavelength; therefore, tuning the antenna to resonance at the operating frequency requires the use of a variable series inductance. By making a slight wiring change in Antenna Tuning Unit BC-939-A, coil L6 is connected in series with the antenna and the variable coupling link of the p-a tank coil. Figure 43 is a schematic diagram of the p-a plate circuit and Antenna Tuning Unit BC-939-A, after the tuning unit wiring has been changed. The antenna, being shorter than a quarter-wavelength, represents a highly capacitive load to the transmitter. However, the antenna can be tuned to resonance at the operating frequency by the proper adjustment of coil L6. When the antenna is tuned to resonance, maximum r-f current is indicated by ANTENNA CURRENT meter M4 and the an
95
tenna presents a purely resistive load to the transmitter. The radiation resistance at the base of a quarter-wave grounded antenna is approximately 36 ohms. The purpose of the variable coupling link of the p-a tank coil is to reflect this resistance into the p-a plate circuit. The magnitude of the reflected resistance depends on the amount of mutual reactance existing between the variable coupling link and the p-a tank coil. The effect of the reflected resistance is to reduce the Q of the p-a tank circuit, and consequently, the impedance of the p-a plate circuit. When the impedance in the p-a plate circuit is lowered, the p-a tube draws more plate current. The correct setting of the variable coupling link is that setting which allows the p-a tube to draw the recommended d-c plate current.
LONG WIRE I ANTENNA |___
r ~i
SWITCH
I SWq SET AT
I 3 Q
2-IOMC ‘ SWQ_
o
COUPLING COILS X
C-4 54 OR C-455 I ( d
v|6 JvT-220 " j I
T# I
HIGH VOLTAGE 4 c2 LZ ANTENNA ^9.1 I
•«----- ------ _23 55 I CURRENT
B+ l_______________j
-1- c12 ZC ANTENNA TUNING UNIT
r /o BC-939-A AFTER WIRING
cll # ________ g CHANGE
0.002 MF
~ TL13804
Figure ^3._ P-a plate circuit and Antenna Tuning Unit BC-939-A—schematic diagram.
Section II. DOUBLET ANTENNA
123. Purpose
The doublet antenna is furnished for operation from a fixed location. It is used to extend the transmitting range of Radio Transmitter BC-610-E several hundred miles. Use of the doublet antenna will increase the range of communication many times over the range obtained with the whip antenna.
124. Description
a. The doublet antenna consists of a halfwave doublet antenna (cut to operating frequency by the operators of the radio set) which is fed by means of a coaxial cable. One end of the coaxial cable is connected to the center of the antenna and the other end is coupled to Radio Transmitter BC-610-E by means of a variable link coil which is part of the transmitter tank coil. Cord CD-1290 is a coaxial cable, 50 feet long, with a connector on each end. The antenna is supported by three masts, each made up of Mast Sections MS-44-A. The masts may be improvised from other materials, if necessary.
b. A list of components contained in the doublet antenna kit follows. There are two Quantity columns. The first quantity column indicates the number of items required for an installation where masts must be used. The second quantity* column indicates the number of
items required for the antenna and coupling system when other means of supporting the antenna are used.
Note. In later models the components making up the doublet antenna set are issued as part of Radio Sets SCR-399-A and SCR-499-A.
c. The coil units are contained in a package prepared for oversea shipment. Mast Sections MS-44-A are packed in the three canvas Rolls BG-176, seven mast sections to each roll. All of the guys, guy plates, mast bases, and stakes are packed in one Bag BG-102-( ). The remaining items, which are required for the antenna system only (column 3), are packed in the other Bag BG-102-( ).
d. As soon as circumstances will permit, Radio Sets SCR-399-A and SCR-499-A will be delivered with the variable link coupling tank coils listed above instead of with fixed link coupling tank coils. When the doublet antenna kit is issued for use with such sets, either the coils will be omitted from the kit or, if issued, should be returned to stock.
125. Location and Erection of Mast
a. The choice of location for the erection of the antenna is largely dependent upon tactical considerations. If possible, a location away from power lines, tall trees, or other obstructions should be selected for best operating results. Consideration of cover will not always permit
96
selection of the best location. In any case, use the best compromise between cover and a clear antenna. The radio set and the antenna must be so located that the cable assembly will reach from the top of the center mast to the transmitter output.
Table VII. List of components in doublet antenna kit
Article Quantity
Complete doublet kit Antenna system only
Roll BG-176 3
Bag BG-102-( ) 2 1
Mast Section MS-44-A 21
Mast Base MP-19 3
Guy Plate MP-20 9
Guy GY-22-A 6
Guy GY-41 12
Guy GY-24-A 3 3
Insulator IN-86-A 12 12
Stake GP-2 18
Reel RL-29 2 2
Steel tape (100-foot) 1 1
Wire W-28 250 ft 250 ft
Cord CD-1290 (50 ft) I1 ll
Coil Unit C-387-D P P
Coil Unit C-388-G P P
Coil Unit C-389-C I2 P
Coil Unit C-390-C P P
Coil Unit C-447-B I2 P
Coil Unit C-448-B P I2
Coil Unit C-449-B P I2
1 This cord is so designed that if additional distance between the doublet antenna and the radio set is required, several sections may be joined together until the desired length is obtained.
2 See d below.
b. The doublet antenna radiates strongest in a direction at right angles (90°) to the plane of its wire. Remember this, as well as the location of the station with which communication is desired, when selecting the position of the masts.
c. Three masts are used to support the antenna; the center mast is used to support the weight of the coaxial-cable feeder line.
d. Erect the masts and install the antenna in accordance with the following procedure:
(1) Cut the antenna wire for the lowest operating frequency to be used. This may be obtained from the formula:
468 Antenna length in feet = ------
F (me)
(F(mc) is the lowest operating frequency in megacycles.) The frequency vs length curve (fig. 44) can be used to obtain the approximate antenna length. To obtain the distance separating the outer masts, add 6 or 8 feet to the length determined above. The third antenna mast is erected at the midpoint, in line with the two
outer masts. See figure 46 for the general layout to be followed.
(2) Select the following parts from the kit for one mast:
7 Mast Sections MS-44-A
6 Stakes GP-2
3 Guy Plates MP-20
1 Mast Base MP-19
2 Guys GY-22-A
1 Guy GY-24-A (antenna halyard)
4 Guys GY-41
(3) At the point selected for one of the outer masts, stake Mast Base MP-19 to the ground with two Stakes GP-2. Use the hammer supplied with the radio set.
(4) Using a radius of 20 feet from Mast Base MP-19, drive in the remaining four Stakes GP-2, 90° apart from one another and at an angle of 45° with the antenna wire. (See fig. 45.)
Note. When measuring off distances on the ground to determine the position of the stakes, a mast section may be used conveniently since its over-all length is 51/2 feet (5 feet NOT INCLUDING the 6-inch ferrule (smaller diameter portion)) at one end.
(5) Assemble the seven Mast Sections MS-44-A with one Guy Plate MP-20 at the top of the mast, another at the junction of the fourth and fifth sections, and the remaining guy plate at the junction of the first and second sections.
(6) Slip the bottom mast section over the mast base.
(7) To one hole in Guy Plate MP-20 at the top of the mast, attach the two ends of Guy GY-22-A and the block of Guy GY-24-A (halyard) by means of the snap hooks. (See fig. 45.) To the hole in the opposite end of the top guy plate, attach the two ends of the remaining Guy GY-22-A. Place all of the rings with block attached (not the center ring) over the corre-ponding Stake GP-2.
(8) To Guy Plate MP-20 at the junction of the fourth and fifth sections near the center of the mast, attach one end of each of the 4 Guys GY-41-A, using two snap hooks in each of the two holes. Since these guys are not used in raising the mast, temporarily tie the loose ends near the bottom of the mast to avoid tangling when the mast is raised.
(9) Guy GY-24-A is used as a halyard to raise and lower the antenna wire. Make sure that this guy will be on the antenna side of the mast after erection. Secure both ends of this guy to a point near the bottom of the mast to
97
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keep it out of the way while the mast is being raised, and also to prevent either end from accidentally getting out of reach.
(10) The mast can now easily be raised. One man grasps the center ring of Guy GY-22-A and walks toward the base of the mast. (See fig. 46(A).) Another man assists in the erection procedure by lifting the mast from the ground
in a manner similar to that used in raising a ladder. At the same time, a man guides the bottom of the mast onto Mast Base MP-19 until the mast is halfway erect, then quickly grasps the center ring of the remaining Guy GY-22-A (fig. 46(B)) and makes the necessary adjustment on the length of the guy when the mast is erect. When the mast has been brought into a
98
/ A \W [Si / ' z/,z \\
VL i„ ©>i I I o \ ' 2°’ /
B*GY-24-A
GUYING DETAIL AM
GUY PLATE MP-20 ,6" FERRULE ABOVE PLATE ——JL--------------=- __ ANTENNA WIRE W-28
--------------------------------------------------------------------------- ■" ^§) © (§/-------------------------------------!>
H ~iK|/ I '-WIRE W-28 __ \ -zQx
f I ‘-INSULATOR IN-86
/ X \ Xj /
/ - I \ \ Z<-|NSULATED COAXIAL-CABLE
/ I \ / TERMINATlNG BLOCK
NOTE; MAST OF 7 SECTIONS. / I \ \ fej /
EACH 5FT. LONG / I \ \ !§] /
/ / \ COAXIAL CABLE I
/ MAST SECTION / \ ASSEMBLY W
/ MS-44-A / \
GUY GY-22-a/ I \
V / JUNCTION OF I \ DETAIL OF CENTER OF
7 iWrlrMl 5TZ^_ _^/ \ ANTENNA AT CENTER
/ “^rrr^L \ MAST
3 5' / yT / / Xv \ MATERIALS REQUIRED TO
/ / l\ \ ERECT ONE MAST
/ / I / X \ 7 MAST SECTIONS MS-44-A
/ / I \ \ 4 GUYS GY-41
/ ~ \ 2 GUYS GY-22-A
/ /—GUY GY-24-X \ 1 GUY GY-24-A
/ / I X \ 3 GUY PLATES MP-20
/ GUY PLATE' I \ 1 MAST BASE MP-19
/ MP-20 J \ 6 ^STAKES GP-2
S) (7f ,,
/fOy / < APPROX 70 OHMS
_______________) —TL 13805
Figure 79. Method of feeding power to the antennas.
b. CORD CD-1290 (50-foot). When an untuned transmission line is used to feed power to the antenna, the line must be terminated in its characteristic impedance. The characteristic impedance of coaxial-cable Cord CD-1290 is approximately 70 ohms. Therefore, an impedance match is effected by connecting the coaxialcable (Cord CD-1290) directly to the center of a half-wave doublet antenna. Cord CD-1290 is supplied in 50-foot lengths. Several lengths can be connected without materially increasing the losses in the transmission line.
c. Coupling Coils. The coupling coils supplied with the doublet antenna kit couple the power amplifier to the transmission line. The seven coils cover a frequency range of 2.0 to 18.0 and are provided with variable link coils. These coils take the place of the fixed link p-a tank coils normally supplied with the transmitter. The desired power output from the power amplifier is obtained by varying the degree of coupling between the p-a plate circuit and the load. This is accomplished as follows: One end of Cord CD-1290 is connected to the center of the half-wave doublet antenna, and the other end is connected to the variable link coil inside
103
the p-a tank coil. The transmission line, which is terminated in its characteristic impedance, represents a purely resistive load of approximately 70 ohms. (See fig. 49.) This resistance is reflected into the p-a plate tank circuit because of the mutual reactance existing between the variable link coil and the p-a tank coil. The magnitude of the reflected resistance increases or decreases as the coupling between the va
riable link coil and the p-a tank coil is increased or decreased. The reflected resistance lowers the Q of the p-a plate tank circuit, and consequently, the impedance in the p-a plate circuit. When the impedance in the p-a plate circuit is lowered, the d-c plate current increases. The correct setting of the variable link coil is the setting which allows the p-a tube to draw the recommended d-c plate current.
CHAPtER 5
CHAPTER 5
REPAIR INSTRUCTIONS
Note. Failure or unsatisfactory performance of equipment used by Army Ground Forces and Army Service Forces will be reported on WD AGO Form 468 (Unsatisfactory Equipment Report). For particulars see paragraph 195. If Form 468 is not available, see
TM 38-250. Failure or unsatisfactory performance of equipment used by Army Air Forces will be reported on Army Air Forces Form No. 54 (Unsatisfactory Report).
Section I. SIMPLIFIED BLOCK DIAGRAMS
130. Radio Transmitter BC-6I0-E, C-W Operation (fig- 50)
Radio Transmitter BC-610-E is a masteroscillator power-amplifier transmitter. The frequency of the transmitted signal is accurately controlled by a variable-frequency or crystal-controlled master oscillator, which is keyed for c-w operation. The output of the oscillator is fed into a buffer-doubler stage. When the variable-frequency master oscillator is used, the buffer-doubler stage operates as a frequency doubler for all frequencies up to 12 me, and as a frequency quadrupler for frequencies from 12 to 18 me. For crystal operation in the 2- to 4-mc range, the buffer-doubler stage is tuned to the crystal frequency, and operates only as a buffer amplifier; in the 4- to 12-mc range, this stage operates as a buffer-doubler; and in the 12- to 18-mc range, it operates as a frequency quadrupler. The buffer-doubler stage
improves the frequency stability of the transmitter by isolating the oscillator stage from the i-p-a and p-a stages. The r-f output of the buffer-doubler stage is adequate to excite the i-p-a stage. In turn, the i-p-a stage develops the power necessary to drive the p-a stage. The p-a stage develops the r-f energy which is radiated from the transmitting antenna. The tuned circuits for the oscillator, buffer-doubler, and i-p-a stages are mounted in a single plug-in tuning unit. The transmitter accommodates three of these plug-in tuning units, any one of which can be selected by the BAND SWITCH. Seven plug-in tank coils and a vacuum capacitor are provided for tuning the p-a stage over the frequency range of the transmitter. The vacuum capacitor is required when operating on frequencies from 2 to 2.5 me. Antenna Tuning Unit BC-939-A couples the transmitting antenna to the output of the p-a stage.
____________________________________________ TRAN SM IT TINgX/^ ANTENNA
I I- L
I I
I ------- ----------:--- (VT-IOO) |
. MO OR RUFFFR \ J „ | ANTENNA
CftWAL DOUBLER ''--' A , TUNING
| osc | UNIT
©t \ TWO I N I
—*■— I VT-II5 ) —► JAN-807 —•— I VT-2201 -[-»— BC-939-A ——>
\ J IN PARALLEL \ J
V—Z I
। JAN-6V6 JAN-6L6 /X JAN-25OTH I
। (vT-IOOJ ----------1 । --------
I I
I |
I |
i :
| RADIO TRANSMITTER BC-6I0-E TLI4473
_______________________________________________________1
Figure 50. Radio Transmitter BC-610-E—simplified block diagram, c-w operation.
105
106
131. Speech Amplifier BC-614-E (fig. 51)
When in use, the remote telephone or the dynamic microphone is connected to the input of the first a-f (audio-frequency) amplifier, but the carbon microphone is connected to the input of the second a-f amplifier. This arrangement provides proper impedance matching without complicated switching arrangements. The output of the first amplifier is applied to the input of the second amplifier which in turn feeds the third a-f amplifier and the phase inverter. A portion of the a-f output of the third amplifier is applied to the modulation limiter. The modu-
used to excite the driver stage for the modulator in Radio Transmitter BC-610-E. The c-w sidetone oscillator and the sidetone amplifier supply a sidetone signal to the headsets during c-w operation.
132. Radio Transmitter BC-6I0-E and Speech Amplifier BC-614-E [Phone Operation] (hg- 52) The output of the speech amplifier is applied to the push-pull driver stage in Radio Transmitter BC-610-E. The power output of the driver is sufficient to operate the push-pull modulator which develops power enough to
I ।
REMOTE I ------------------ -------------------------------------- I
TELEPHONE EE-8-Q | 1 ST A-F AM PLIF IE R SIDETONE
—I---- OSCILLATOR
7T\ I TO KEYING
I VT - 231 J --r*-
V J I CI.RCUIT
DUAL TRIODE i ID---------------------1--- JAN -6SQ7 MODULATION-JAN-6SN7GT I
' LIMITER
CARBON | '—
_____MICROPHONE------1---------- , > ---------- Lf- ’ I
1 'll . (
I 2D A-F AMPLIFIER JAN-6SR7 SIDETONE
__________ AMPLIFIER - I
X \ XX\ I TO HEADSET JACKS ON
IVT-941 IVT-94I -(-►
J \______J | JUNCTION BOX JB-7O-A
| JAN-6J5 ‘ JAN-6J5 |
| ------------ -------- ------------------------------------- |
I H I
! 3D A-F AMPLIFIER AND 4TH A-F AMPLIFIER ।
PHASE INVERTER | To RAD|0
1 X------X ----- /-----------------\ | TRANSMITTER
I ( VT-231 ) -----*•--- ( VT-231 ) -‘-►BC-CIO-E
| X- J X.______y | DRIVER STAGE
DUAL TRIODE DUAL TRIODE
JAN-6SN7GT JAN-6SN7GT
; I.
SPEECH AMPLIFIER BC-6I4-E j TLI4464
Figure 51. Speech Amplifier BC-614-E—simplified block diagram.
lation limiter produces a d-c control voltage which is applied to the second audio stage as a bias voltage which reduces the gain and prevents over-modulation of the transmitter. The outputs of the third a-f amplifier and the phase inverter are coupled to the fourth amplifier. The output voltage of the fourth amplifier is
modulate the transmitter properly. The output of the push-pull modulator is applied to the p-a stage in which the r-f and a-f voltages are combined to produce the amplitude-modulated r-f energy that is radiated from the transmitting antenna. For a discussion of the other stage shown in figure 52, see paragraphs 130 and 131.
Section II. THEORY OF RADIO TRANSMITTER BC-610-E
133. Oscillator Stage
The m-o stage develops r-f oscillations which are stable in frequency. The m-o stage can be operated as an electron-coupled variable-frequency oscillator, or as a crystal-controlled electron-coupled oscilla
tor. (See fig. 53.) The M.O.-XTAL switch SWi5 on the tuning unit is used to select the desired type of m-o operation. For simplicity, only the variablefrequency oscillator is called the master oscillator; however, the crystal oscillator is also a master oscil-
107
TRANSMITTING V 7 ANTENNA X /
r------------------------------------------------------------.
1 I PA
। MO 0R BUFFER LT-l0d I ANTENNA
I CRYSTAL OSC DOUBLER X--/ TUNING
©Z X TWO Z I UNIT
—* IVT-II51 —* JAN-607 -»— (VT-220) --!•— BC-939-A
V Z IN PARALLEL y
| JAN-6V6 JAN-6L6 Z^N JAN-250TH |
' M e —
RADIO TRANSMITTER BC-6I0-E ”
REMOTE । ! _____________________________I
TELEPHONE EE-a-0 | 1ST A-F AMPLIFIER I
। | DRIVER MODULATOR I
(VT-1031 I Z \ Z "X
DYNAMIC l\.y I (VT-95) (VT-218)
prx_____MICROPHONE >--/ ___________ V y \ J
I JAN-6SQ7 MODULATION I ---Z ----'
CARBON I ------------------ LIMITER I TWO TWO
MICROPHONE I f \ ' JAN-2A3 —w— JAN-IOOTH I
UJ------------------1----1 ” |--*--- IVT-233 J | IN PUSH-PULL IN PUSH-PULL
i —I——L O । I
| 2D A-F AMPLIFIER JAN-6SR7 | I X f \ |
l O' V7 I
I
I ____,________ _____________ ।
| JAN-6J5
# - l
3D A-F AMPLIFIER AND 4TH A-F AMPLIFIER I
PHASE INVERTER ____PUSH-PULL 1
/-----\ /-----X 1
(vT-23lJ — (vT-23l) I
DUAL TRIODE DUAL TRIODE
I JAN-6SN7GT JAN-6SN7GT
SPEECH AMPLIFIER BC-6I4-E ! TLI446S
Figure 52. Radio Transmitter BC—610—E and Speech Amplifier BC—614—E—simplified block diagram, phone operation.
lator in Radio Transmitter BC-610-E. The operation of both oscillators is explained in terms of the Hartley oscillator.
a. Hartley Oscillator. For purposes of comparison, each part in the Hartley circuit (fig. 54(A)) is given the part number of the corresponding part used in Radio Transmitter BC-610-E. The functioning of the parts in the shunt-feed Hartley oscillator (fig. 54(A) ) is as follows:
(1) The screen grid of tube V8 (Tube JAN-6V6 (VT-107) ) acts as the anode (plate) of a triode oscillator for which the control grid and cathode form the other two triode elements.
(2) Inductor L8 is connected so that the turns between 1 and 2 are between the grid and cathode,
and the turns between 2 and 3 are between the cathode and plate.
(3) Capacitors C3i and C36 are connected in parallel across inductor L8 so that L8 and C3i plus C36 form the resonant LC circuit. The resonant frequency can be adjusted by means of variable capacitor C3i.
(4) Capacitor C42 is the grid capacitor.
(5) Capacitor C2 blocks the d-c plate voltage from the tuned circuit and the grid, but couples r-f variations to inductor L 8.
(6) Choke coil CHi isolates r-f voltages on the grid.
(7) Resistor Ri is a grid leak and acts with the grid capacitor to provide grid bias.
108
C.I3 tuning unit CRYSTAL CONTROL i i
TU - 47 ------------------------r--------- ---------*“
I ~ i V8 3OOV 150 MMF
| XTAL ] ^X-^yT-107
°y f \ 150 V TO BUFFER-
_ NoJ_____„ . _ -T--f----- ’ DOUBLER
° | ISW .. । '&---°------------1-----I 0.006MF J STAGE
I M0 I 15 ' S "-e \ , 7 C
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(8) Before the key is closed, the bias is zero. When the key is closed, d-c supply voltage is applied between the oscillator anode and cathode. This change of plate voltage causes a flow of energy from the anode through capacitor C2 and the plate section (2-3) of coil L8 to the cathode. This current in the plate section of L8 induces a voltage across both the plate and the grid section (1-2) of L8. The voltage induced across L8 charges capacitor C3i and C36, and the resonant circuit starts oscillating. The oscillating current in L 8 causes an r-f voltage across both sections of the coil. The voltage across the grid section (1-2) is coupled through the grid capacitor to the grid, and this voltage is the grid excitation voltage. The excitation voltage is an r-f voltage at the resonant frequency of L8, C3X, and C32. As the excitation voltage varies the grid to cathode voltage, corresponding variations of anode voltage occur and additional energy is fed back through C2 to the plate section of L8 in the resonant circuit. The energy thus fed back is sufficient to make up for the losses in the resonant circuit, so that its oscillations continue. As the grid excitation voltage swings the grid positive, capacitor C42 charges to a voltage nearly equal to the positive peak of the excitation voltage. The voltage of C42 acts as a bias voltage. Grid leak Ri prevents C42 from discharging rapidly when the excitation voltage is lower than the grid capacitor voltage. In other words, the grid capacitor and the grid leak work together to develop the bias voltage for the oscillator stage.
b. Modified Hartley Circuit in Master Oscillator. The modified Hartley circuit of Tuning Unit TU-47 (fig. 54(B) ) operates the same as the ordinary Hartley circuit, except for the following circuit changes:
(1) Chokes CH2 and CH 9 are inserted between the cathode of V8 and the key.
(2) R35 is across CH9 and acts as a parasitic suppressor.
(3) Capacitor Ci is between the cathode of V8 and point 2, the junction of the plate and grid sections of L8.
(4) When the key is closed, the cathode is connected through the low d-c resistance of choke coils CH2 and CH9 to ground. The oscillator action is then the same as explained in a above, except that the high r-f impedance of choke coils CH2 and CH 9 forces the r-f variations at the oscillator anode to feed back through the lower r-f impedance of the cathode section (2-3) of L8. Capacitor Cx is included to keep the d-c current from flowing through the cathode section of L8, but Ci effectively connects the cathode to point 2 at radio frequencies.
Thus in this circuit, the cathode is above ground at r-f potentials.
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135. Buffer-Doubler Stage (fig. 55)
The r-f signal from the oscillator is fed through blocking capacitor Ci3 to the grid of tube V 9 (Tube JAN-6L6 (VT-115)), which is operated as a Class C amplifier. The operating grid bias is developed across grid leak R23 when excitation voltage is applied to the grid. When no excitation voltage is applied to the grid, a protective bias is provided by the cathode bias resistor R24 which is bypassed by capacitor C8. This bias prevents excessive plate current through V 9 during the key-up periods of c-w transmission as well as when the grid is not properly excited because of oscillator failure. The plate-tank circuit consists of variable capacitor C32 and coil L2 0 in the tuning unit and it is connected to the plate of tube V 9 through contacts on switch SWn. The plate-tank circuit is tuned by variable capacitor C32, which is controlled from the tuning unit by a knob marked DOUB. Plate voltage is supplied by the exciter
power supply, and is applied through coil L20, r-f choke coil CII5, and meter shunt resistor R33. Choke CH 5 offers high impedance to r-f currents, and accordingly these currents flow to ground through bypass capacitor C26 which has negligible reactance at operating frequencies. The tube receives screen-grid voltage through screen-dropping resistor R25 and meter shunt resistor R33. Bypass capacitor C4 maintains the screen grid at r-f ground potential. When switch SW8, the EXCITATION METER SWITCH, is set to DOUBLER PLATE, the EXCITATION METER Mi indicates the sum of the plate and screen currents through tube V 9. When the master oscillator is used, the buffer-doubler stage operates as a frequency doubler for all frequencies up to 12 mc; for frequencies from 12 to 18 mc, the buffer-doubler stage operates as a quadruples When the crystal oscillator is used, this stage operates as a buffer amplifier in the 2-to 4-mc
range; as a frequency doubler in the 4- to 12-mc range; and as a quadrupler in the 12-to 18-mc range. The r-f output from the buffer-doubler tank is coupled through capacitor Ci4 to tubes Vio and Vn.
136. Infermedia+e-Power-Amplifier Stage (fig. 56)
Tubes V10 and Vn (Tubes JAN-807 (VT-100) ) are connected in parallel and operated as a Class C amplifier stage. The grid bias for Class C operation is furnished by the bias power supply and applied to the grids of tubes Vio and Vn through parasitic resistors R2i and R22, r-f choke coil CH7, resistor R8, and meter shunt resistor R28. A small amount of self bias is obtained as a result of rectified gridcurrent flow through resistor R8. This feature improves the Class C operation. When switch SW 8 is set to INT. AMP. GRID, meter Mi indicates the grid current for tubes Vio and Vn. Grid excitation voltage is obtained from tube V 9 through coupling capacitor Ci4. The excitation voltage is applied to the grids of tubes Vio and Vn through parasitic resistors R2i and R22 which effectively prevent this stage from producing parasitic oscillations. The high r-f impedance of choke CH7 confines the r-f excitation voltage to the grids of Vio and Vn, thus keeping r-f energy out of the bias power-supply circuits and insuring maximum grid excitation voltage. The plate-tank circuit consists of variable capacitor C34 and coil L2e, in the tuning unit, and it is con
nected to the plates of tubes V10 and Vn through the contacts on switch SWn. The plate-tank coil is tuned to resonance by variable capacitor C34, which is controlled by the knob marked INT AMP on the tuning unit. Plate voltage is supplied by the exciter power supply and is applied to the plates of tubes Vio and Vn through coil L26, r-f choke coil CH6, and meter shunt resistor R27. R-f energy is kept out of the power-supply circuit by the action of choke CH6 and bypass capacitor C24. The screen grids obtain voltage through screen-dropping resistors R6 and R7 and meter shunt resistor R27. Capacitors C6 and C7 are the screen grid r-f bypass capacitors. When switch SW8 is set to INT. AMP. PLATE, meter Mi indicates the total plate and screen current for tubes V10 and Vn.
137. Power-Amplifier Stage (fig. 57)
The r-f output of the intermediate power amplifier is coupled through capacitor C15 to the grid of poweramplifier tube Vie. Tube Vi6 (Tube JAN-250-TH (VT-220) ) is operated as a Class C, plate-neutralized, power amplifier. The grid bias required for this class of operation is furnished by the bias power supply. It is applied to the grid of tube VX6 through r-f choke coil CH8 and meter shunt resistor R26. Choke CH8 confines the r-f excitation voltage to the grid and keeps r-f energy out of bias powersupply circuit. When switch SW 8 is set to P. A. GRID, meter Mi indicates the p-a grid current,
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112
tube Vie. The plate-tank circuit consists of variable capacitor Ci2 and p-a tank coil L7. The p-a tank circuit is tuned to resonance by the variable capacitor C12 which is controlled by the PLATE TUNING dial on the front of the transmitter. Plate voltage for tube V16 is furnished by the high-voltage power supply and is applied to the plate through P. A. PLATE meter M2, r-f choke coil CH4, and coil L7. For phone operation the secondary winding of modulation transformer T 9 is also included in the plate-voltage circuit. Meter M2 indicates the p-a plate current. Radio frequency energy is kept out of the plate power supply circuit by means of bypass capacitor Ou. The inductance of choke CH4 together with its distributed capacitance forms a parallel-resonant circuit at a frequency between 2 and 4 me. Accordingly resistor R9 is placed in parallel with choke CH4 to prevent a high oscillating current in the choke coil. An out-of-phase voltage is fed back to the grid of tube Vi6 through capacitors Ci8 and C29 to neutralize the effect of the interelectrode capacity existing between grid and plate in the p-a tube (plate neutralization). Capacitor C29 has a low reactance at the signal frequency and serves only as a d-c blocking capacitor to isolate the neutralizing capacitor C48 from the high d-c voltage of the p-a plate-tank circuit. Bypass capacitors C9 and Ci0 maintain the filament circuit of tube Vi6 at r-f ground potential, and filament meter M3 indicates the a-c voltage applied to the filament. R-f power is taken from the p-a tank circuit by means of a link inductively coupled to the tank coil, and power is fed to the antenna tuning unit through a short coaxial cable. When the transmitter is not in operation, contacts on relay RY4 short circuit the coupling link and
detune the transmitting antenna so that it does not absorb signal energy at the frequency to which the radio receiving equipment is tuned.
138. Antenna Tuning Unit ( g. 58)
Antenna Tuning Unit BC-939-A is used to match the impedance of the transmitting antenna to that of the final p-a tube plate circuit. The tuning unit is so designed that the transmitter will operate satisfactorily with a five-section rod antenna or with a long wire auxiliary antenna over a frequency range of 2.0 to 18 me. Figure 59 is a functional schematic drawing of the antenna tuning unit when it is connected to a five-section rod antenna and the antenna range switch SW9 is set to 2-10MC. Since the antenna is electrically much shorter than a quarter-wavelength, it presents a highly capacitive load to the transmitter. This capacitive antenna can be tuned to resonance by the addition of a portion of inductance L6, the low-frequency loading coil, which is made variable by a movable tap is controlled from the front panel of the tuning unit by a crank handle marked FREQUENCY 10MC— INCREASE—2MC. When the inductive reactance of coil L6 is made equal to the capacitive reactance of the antenna, the load presented to the transmitter is purely resistive. Coupling coil L5, which is link-coupled to the p-a tank coil, acts as an impedance-matching transformer so that the resistance of the antenna, as reflected back into the p-a tank circuit, presents the optimum plate-load resistance, as viewed from the plate of the p-a tube. Coil L5 is made variable by a movable tap which is controlled by a knob marked COUPLING INCREASE. Figure 60 is a functional schematic of the tuning unit connected to a five-section rod
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Vacuum capacitor C3o is included in the circuit to provide the necessary capacitance when the reactance of the antenna is inductive because of the length of the wire and the frequency used. ANTENNA CURRENT meter M4 indicates the r-f current flowing in the series circuit which consists of the antenna and the antenna loading circuit. R-f current will be at maximum when the antenna is tuned to resonance with the transmitter frequency by means of the antenna loading circuits in the antenna tuning units.
139. Modulator Section
a. Driver Stage (fig. 62). Tubes Vi and V2 (Tubes J AN-2 A3 (VT-95) ) are operated as Class AB], a-f amplifiers connected in a push-pull circuit. The suffix 1 after AB denotes that grid current is not allowed to flow during any part of the input cycle. Plate voltage for tubes Viand V2 is furnished by the bias-voltage power supply. This power supply has the positive side of the output voltage grounded, and therefore the ungrounded side of the output voltage is approximately 360 volts negative with respect to ground. The filaments of the driver tubes are connected through resistor R20 to 360 volts negative, and the plates are connected to ground through the center tap of driver transformer T 8. This places the plates at a potential of approximately 300 volts positive with respect to the filaments. Approximately 60 volts negative grid bias is obtained as a result of the voltage drop
across resistor R20 because of the d-c plate-current flow. The grids are connected to the negative side of resistor R20 through the center tap on input transformer T7. Resistor R20 is bypassed by capacitor C27 which has enough capacity to offer a very low reactance to all audio frequencies above approximately 50 cps (cycles per second). Its purpose is to keep the a-f voltage out of the bias power supply and to prevent degeneration of the a-f signal in self-biasing resistor R20. A-f voltage is fed to the primary winding of transformer T7 over a 500-ohm transmission line. The secondary winding of transformer T7 is connected to the grids of tubes Vi and V2; the grid circuit is completed to the filaments through the center tap on transformer T7 and resistor R20. The primary-to-secondary turns ratio of transformer T7 is such that when the secondary is loaded by resistor Ri4 and Ri5, the impedance, looking into the primary winding, is 500 ohms. This is the correct impedance to properly terminate the a-f transmission line from the speech amplifier. The driver stage is coupled to the modulator stage by transformer T 8. The secondary winding of transformer T8 is loaded by resistors Rig and R17 to provide a more constant plate-load impedance for the driver tubes.
b. Modulator Stage (fig. 62). Tubes V3 and V4 (Tubes JAN-100-TH (VT-218) ) are operated as a Class B push-pull modulator stage. Class B operation requires that the tubes be biased near plate current cut-off. Under this condition, the
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plate current which flows when no signal is applied to the grids is relatively small; but when peak signal voltage is applied to the grids, the plate current may rise to several times the zero signal value. Grid bias for tubes V3 and V4 is furnished by the bias power supply, and during phone operations, is applied to the grids through contacts on relay RY3 and the secondary center tap on transformer T8. The bias voltage is set to the correct value by potentiometer R12, the MODULATOR BIAS control on the front of the transmitter. During c-w operation, potentiometer Ri2 is disconnected by contacts on relay RY3, and the total output voltage of the bias power supply is applied to the grids of tubes V3 and V4 through resistor R34. This voltage is sufficient to cause plate current cut-off. Plate voltage for the modulator stage is furnished by the high-voltage power supply, and is applied to the plates through the center tap on modulation transformer T 9. The filaments of tubes V3 and V4 are connected to ground through resistor R5 in parallel with MODULATOR PLATE meter Mi Oi. Meter Mioi is located in the speech amplifier and indicates the d-c plate current for tubes V3 and V4. If meter Mioi or the circuit to the meter becomes open, resistor R 5 provides a protective bias for tubes V3 and V4, regardless of the setting of MODULATOR BIAS control R12. In addition, it maintains the filament circuit
of the modulator tubes and the wiring to the meter near ground potential. Under certain conditions, it may be necessary to apply plate power to the transmitter without having the speech amplifier and junction box connected. This can be done by setting PLATE POWER switch SW6 to ON; resistor R5 affords the protection described above. The a-f voltage developed across the secondary of transformer T 9 adds to and subtracts from the d-c plate voltage applied to the p-a tube. Because the r-f output voltage of a Class C amplifier is proportional to the applied plate voltage, the r-f carrier is amplitude modulated by the a-f voltage developed in the modulator stage. Transformer T9 is, in effect, loaded by a resistor whose value is equal to the d-c plate resistance of the p-a tube. Because of the impedance-transforming properties of transformer T 9, the resistance which is reflected into the primary circuit is the optimum plate-load impedance for modulator tubes V3 and V4. During c-w operation, the secondary winding of transformer T9 is short-circuited by a pair of contacts on relay RY3.
140. Power Supplies
a. Exciter Power Supply (fig. 63). The exciter power supply furnishes plate and screen-grid voltage for oscillator tube V8, buffer-doubler tube V9 and intermediate-amplifier tubes Vio and Vn. Fila-
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116
ment transformer T4 has three low-voltage secondary windings. They are: (1) 5.0-volt, 10.5-ampere, (2) 6.3-volt, 3.5-ampere, and (3) 5.0-volt, 3-ampere. The 5.0-volt, 10.5-ampere winding furnishes filament current for p-a tube VieJ the 6.3-volt, 3.5-ampere winding furnishes heater current for tubes V8, V9, Vio, and Vn; and the 5.0-volt, 3-ampere winding furnishes filament current for rectifier tube Via. Rectifier tube Vi2 (Tube JAN-5Z3 (VT-145)) is connected in a full-wave rectifier circuit. The
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b. Bias Power Supply (fig. 64). The bias power supply furnishes filament and plate voltage for tubes Vi and V2, and bias voltage for tubes Vio, Vn, Vi6, V3 and V4. Transformer Tx supplies filament and plate voltage to rectifier tube V5 (Tube JAN-5Z3 (VT-145) ) which is connected as a full-wave rectifier. The rectifier output voltage is applied to a choke input pi-section filter consisting of filter chokes L2 and L3, and capacitors C20 and C2i. Resistor R11 and potentiometer Ri2 connected across the output of the power supply serve as bleeder resistors. The voltage regulation of this power supply is relatively good because of the use of a choke input filter and a high value of bleeder current. An adjustable tap is provided on resistor R11 for the purpose of adjusting the bias voltage to tubes Vio, Vn, and Vie to the correct value. Filament current for modulator tubes V3 and V4 is supplied by filament transformer T3. The function of all other parts shown in figure 64 has been described in other paragraphs.
c. High-voltage Power Supply (fig. 65). The high-voltage power supply furnishes d-c plate voltage for modulator tubes V3 and V4, and p-a tube V16. Tubes V6 and V7 (Tubes JAN-866A (VT-46A)) are connected in a full-wave rectifier circuit. Transformer T2 furnishes filament current to the rectifier tubes; transformer T6 furnishes the high a-c voltage to the rectifier plates. The rectified high voltage is applied to an L-section filter consisting of filter choke L4, and filter capacitors Ch9 and C23 in parallel. Resistor Ri3, the bleeder resistor, is connected across the output of the power supply and serves to discharge capacitors Ch 9 and C23 when the power is turned off. Switch SW7, the C.W.-PH0NE switch, reduces the voltage applied to the plates of the rectifier tubes during phone operation. Switch SW4 is the HIGH VOLTAGE PROTECT switch. When set to HIGH VOLTAGE PROTECT it connects resistor R19 (heater element) in series with one side of the primary of transformer T6 to reduce the output voltage of the rectifier during tune-up
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to p-a tube Vie during tune-up operations. When d. Plate Power Switch SWg (fig. 68). PLATE switch SW4 is set at OFF, it short-circuits resistor POWER switch SWg is located on the front panel
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Figure 69. C.W. PHONE switch—functional diagram.
119
of the transmitter. When set to ON, it applies voltage to the coil of relay RYi. A pair of contacts on relay RYi applies power to the primary winding of high-voltage transformer T6.
e. C. W. Phone Switch SW7 (fig. 69). C. W. PHONE switch SW7 is a four-pole, double-throw toggle switch located on the front panel of the transmitter. Its purpose is to select either c-w or phone operation. In the C. W. position, switch SW7 applies a-c power to only a portion of the primary winding of transformer T6. Thus full plate voltage is applied to the p-a tube. In the PHONE position, switch SW7 applies a-c power to the whole primary winding of transformer T6 and, as a result, reduced plate voltage is applied to p-a tube Vi6 and modulator tubes V3 and V4. Two poles of switch SW7 are connected in parallel to carry the primary current required by transformer T6. In the PHONE position, another pole on switch SW7 applies voltage to the coil of relay RY3. The con
tacts on relay RY3 short-circuit the secondary winding of modulation transformer T 9, and these contacts remain closed until current flows through the coil of relay RY3. One pole on switch SW 9 is not used.
Caution: Never throw this switch when the plate power is turned on. To do so will damage the switch, because the switch is not designed to break the primary current to high-voltage plate-power transformer T6.
f. Band Switch SWu (fig. 70). Switch SWu is a four-section, three-position switch, controlled from the front panel of the transmitter by a knob marked BAND SWITCH. Its purpose is to provide selection of any one of three tuning units which have been set to a predetermined frequency. The switch sections are numbered (on the functional schematic diagram) SWu-i, SWu.2, SWu-3, and SWn.4. Section 1 is the section nearest the front panel of the transmitter. Switches SWu-i and
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functional diagram. J g
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set to INT. AMP. PLATE, meter Mi is connected I ZSWITCHES | >R
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h. Overload Reset Switch SWi2 (fig. 72). K 1 K
Switch SWi2 is a momentary push-button type of C* t6 o
switch located on the front panel of the transmitter. 0RY2 1
The switch is normally closed; but when pressed, it A_c C0MM0N | |
interrupts the energizing current through the coil 4 TL14403
of overload reset relay RY2, which in turn operates Figure 73. Interlock switches—fzmctional diagram.
121
high voltages. Their purpose is to disconnect the a-c power from the primary winding of high-voltage power transformer T3. On transmitters with aerial numbers below 5191, switches SW2, SW5, SWi0, and SWi3 are connected in series with the coil of relay RYi. Beginning with serial number 5191, the interlock wiring has been changed; and switches SW2 and SWi3 are connected in series with the contacts of relay RYi, providing positive protection even though the contacts on relay RYi should freeze closed. Interlock switch SWi0 is not used on transmitters with serial numbers above 5191. Switch SW2 is located on the under side of the lefthand top cover just above the r-f tank coil. Switch SW 6 is located on the rear apron of the modulator deck of the transmitter in such a manner that the switch opens when the rear cover of the transmitter is removed. Switch SWi3 is located on the under side of the right-hand top cover and operates when the door over the tuning units is opened. On transmitters with serial numbers below 5191, switch SWio is installed in such a manner as to disconnect the a-c power from transformer T6 when the entire top section of the transmitter is removed.
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Figure 74. Plate power relay RY,—functional diagram.
142. Relays
a. Plate Power Relay RYi (fig. 74). Relay RYi is a double-pole, single-throw relay located on the modulator deck of the transmitter. Its purpose is to apply plate power to the transmitter. When the coil of relay RYX is energized, one pair of the relay contacts applies a-c power to the primary winding of the high-voltage power transformer T6 and the other pair of contacts apply a-c power to the primary winding of the exciter power-supply transformer T5.
b. Phone-continuous Wave Switching Relay RY3 (fig. 75). Relay RY3 is a double-pole, doublethrow relay located on the modulator deck of the transmitter. This relay operates in conjunction
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Figure 75. Phone-continuous wave switching relay RY3—functional diagram.
with the C.W. PHONE switch SW7 and its purpose is to select either c-w or phone operation. When switch SW7 is set to C.W., no current flows through the coil of relay RY3 and a closed pair of contacts short-circuit the secondary winding of modulation transformer T 9. When switch SW7 is set to PHONE, the coil of the relay is energized and the closed contacts which short-circuit the secondary winding of transformer T 9 are drawn apart, removing the short circuit. At the same time, another pair of contacts on relay RY3 close and these contacts apply the correct bias for Class B operation of modulator tubes V3 and V4 through potentiometer R12-
c. Antenna Shorting Relay RY4 (fig. 76). Relay RY4 is a double-pole, double-throw relay located on the r-f deck of the transmitter near the p-a tank coil. Its purpose is to short-circuit the antenna-coupling coil of the p-a tank coil when the transmitter is not in operation. The coil of relay RY4 is connected in parallel with the coil of relay RYi; therefore both relays operate at the same time. When relay RY4 is not energized, the contacts are connected in series across the antenna-coupling coil, shorting it out. When the relay is energized, the contacts are drawn apart, removing the short circuit from across the coupling coil.
d. Overload Protection Relays RY2 and RY5 (fig. 72). Relays RY2 and RY5 are located on the lower deck of the transmitter. They protect high-voltage rectifier tubes V6 and V7 from damage due to heavy current surges or serious overloads. All current drawn from the high-voltage power supply must pass through the coil of relay RY5 and is designed to operate the contacts when the current through the coil exceeds approximately 750 ma.
122
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123
meter indicates the p-a grid current on the 0- to 150-ma scale; resistor R26 is the meter shunt resistor.
d. P. A. Plate Meter M2 (fig. 65). P. A. PLATE meter M2 is a 0- to 500-ma, d-c milliameter located on the front panel of the transmitter. Its purpose is to indicate the d-c plate current of p-a tube Vi6. The meter is connected in the high-voltage plate lead to tube Vi6, and is isolated from the radio frequency in the tank coil by r-f choke coil CH4 and bypass capacitor Cm
e. Fil. Voltage Meter M3 (fig. 66). Filament voltage meter M3 is a 0- to 10-volt a-c voltmeter
located on the front panel of the transmitter. It indicates the filament voltage to p-a tube Vi6. The meter is connected directly across the filament winding of transformer T4 which supplies filament current to p-a tube Vi6. Since the primary windings of transformers T2, T3, and T4 are connected in parallel and receive a-c primary current through the common variable resistor Ri8, it necessarily follows that when resistor Ri8 is adjusted so that meter M3 indicates the correct voltage across the filament winding of transformer T4, the filament voltages supplied by transformers T2 and T3 will also be nearly correct.
Section III. THEORY OF SPEECH AMPLIFIER BC-6I4-E
144. First A-F Amplifier (fig. 78)
Tube Vioi (Tube JAN-6SQ7 (VT-103) ) is connected as a triode in a Class A resistance-coupled amplifier stage. Its purpose is to amplify the output of dynamic Microphone T-50 or remote Telephone EE-8-( ). The tube is self-biased as a result of the d-c voltage drop across the cathode-bias resistor Rio6- Plate voltage is furnished by the power supply in the speech amplifier, and is applied to the plate of tube Vioi through a decoupling resistor Ri28 and plate-load resistor R107. Capacitor Cm is the a-f bypass capacitor for decoupling resistor Ri28. The filter, consisting of resistor R428 and capacitor Cm, prevents feedback from succeeding stages because of coupling through the common impedance of the power supply. The network in the grid circuit, consisting of resistors R101, R102, R103, Ri04, and Rio5, is designed to properly match the impedance of either dynamic Microphone T-50 or a telephone line, the far end of which is connected to a field Telephone EE-8-( ). Microphone T-50 requires high-impedance input; Telephone EE-8-( ) requires a low-impedance input. In addition to matching impedance, the network also provides the correct attenuation of the input a-f voltage when using Microphone T-50 or field Telephone EE-8-( ). This is a necessary function because the output voltage levels of Microphone T-50 and Telephone EE-8-( ) differ considerably. Solution of the resistance network, consisting of resistors R101, R102, R103, R104, and Rios, yields the equivalent circuits shown in figure 78(A) and (B). Figure 78(A) is an equivalent circuit of the 1st a-f amplifier stage when using Microphone T-50; figure 78(B) is an equivalent circuit when using remote Telephone EE-8-( ). In either case, the a-f voltage applied to the grid of tube Vioi is, in effect, obtained from a tap on a voltage divider. When using Microphone T-50, the microphone output voltage is attenuated
approximately 15 decibels; when using remote Telephone EE-8-( ), the degree of attenuation is approximately 20 decibels. Capacitor Ci30 is an r-f bypass capacitor to prevent high-frequency interference from affecting the amplifier when the input is connected to a telephone line. The output voltage of tube Vioi is developed across resistor Ri07 and is applied to the grid of the second a-f amplifier through audio-coupling capacitors C102 and C119.
145. Second A-F Amplifier (fig. 79)
Tube V102 (Tube JAN-6J5 (VT-94)) is operated as a Class A resistance-coupled amplifier stage. Its purpose is to amplify the output of the first a-f amplifier tube Vioi and to amplify the output of a carbon microphone when one is used. Bias voltage is provided partly by the modulation limiter and partly from the self-biasing action of resistor Rn2 in the cathode circuit. The action of the modulation limiter is described in paragraph 148. Plate voltage is applied through decoupling resistor RX27 and plate-load resistor Rm. Capacitor Cm is the a-f bypass capacitor for decoupling resistor Rm. The decoupling filter consisting of resistor R427 and capacitor Cn2 performs the same function as the decoupling filter described in paragraph 144. When a dynamic microphone or field telephone is used, the output voltage of the first a-f stage is impressed on the grid of tube V102 through coupling capacitor Ci02, resistor Rios, potentiometer Rm (gain control), and another coupling capacitor Cn9. Capacitor C119 also serves as a d-c blocking capacitor for the bias voltage supplied by the modulation limiter. The purpose of resistor Rios is to provide a more constant plate-load impedance for tube Vioi as the gain control Rm is varied. This improves the low-frequency response of the amplifier at low settings of gain control Rm. Gain control Rm controls the output of the speech amplifier when using a dynamic
124
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of tube Vio3. The plate circuit of this section of tube V103 provides, through capacitor Choe, a signal for grid 2 of tube Vi04 which is opposite in polarity at any instant to the signal applied to grid number 1 of tube Vio4- This signal voltage also appears across resistors Rn9 and Ri20. Resistors Rug and Rii9 are equal in resistance value. As the signal applied to grid 1 of tube Vi 0 4 becomes greater than the signal applied to grid 2, the polarity, at any instant, of the voltage developed across resistor Ri2o is such as to cause greater instantaneous output from the phase inverter section of tube Vi03. The two grids of tube Vi04 are therefore excited almost equally, and the voltage drop across resistor
R120, caused by the signal applied to grid 1 of tube Vio4, is almost cancelled by a voltage of opposite polarity and nearly equal amplitude caused by the signal applied to grid 2 of tube Vio 4. The remaining uncancelled voltage across resistor R120 corresponds to the unbalance between the signals applied to the two grids of tube Vi04. This unbalanced voltage then excites the grid of the phase-inverter section of tube Vi 03 so that the output of the phase inverter tends to reduce the unbalance. The high gain of tube Vi03 results in a very small percentage of unbalance, even with considerable variations in the two sections of tube V103 and variations in circuit constants.
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126
147. Fourth A-F Amplifier (fig. 81)
Tube V104 (Tube JAN-6SN7 (VT-231) ) is connected in a Class A push-pull amplifier stage. Its purpose is to amplify the output of the third a-f amplifier stage sufficiently to excite the grids of the push-pull driver stage located in the transmitter. The tube is self-biased as a result of the d-c voltage drop across cathode-bias resistor Ri24 which is bypassed for audio frequencies by capacitor Ci07. Plate voltage is obtained from the speech-amplifier
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power supply, and is applied to the plates of the tube through the center tap on the push-pull output transformer Ti02. Transformer Ti02 is designed to match the plate-to-plate impedance of tube V104 to a 500-ohm transmission line. Grid excitation for tube V104 is provided by the third a-f amplifier and phase inverter. The a-f output voltage appearing across the secondary winding of the output transformer is fed to the driver stage in the transmitter over a 500-ohm transmission line.
148. Modulation Limiter (fig. 82)
Tube V105 (Tube JAN-6SR7 (VT-233) ) is com nected in a modulation limiter circuit. Its purpose is to produce a d-c control voltage which is proportional to the peak amplitude of the speech-amplifier output voltage. This d-c control voltage is then used to bias the second a-f amplifier tube; its effect is to vary the gain of the second a-f amplifier tube V4 02 in inverse proportion to the amplitude of the output voltage of the speech amplifier. Tube V-ot performs two functions: The triode section of the tube functions as an a-f amplifier, and the two diodes are connected in a full-wave rectifier circuit. The tube is self-biased as a result of the d-c voltage across cathode-bias resistor R13i and plate voltage is applied through decoupling resistor R129 and plate-load resistor R130. Capacitor Cn5 is the a-f bypass capacitor for resistor R129. Excitation voltage for the grid of tube Vi0Sis obtained from one of the grids of tube Vi04 through potentiometer R134, the modulation LIMITER CONTROL. The a-f output voltage of tube V405 appears across resistor R130 and is applied to the primary winding of transformer Ti04 through audio-coupling capacitor Cn4. The a-f voltage appearing across the secondary winding of transformer Ti04 is applied to the two diodes of tube V405 and the diodes are returned to ground through the center tap of the secondary winding and diode load resistor R i33. The rectified a-f voltage which appears across resistor R133 is filtered by an RC (resistance-capacitance) network consisting of resistor Ri32 and capacitor Cn6. The d-c voltage appearing across capacitor Cn6 is ap-
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127
proximately equal to the peak amplitude of the signal applied to the diodes of tube V105, and this d-c voltage is applied to the grid of tube V102 through resistor Rio9. Tube V102 is operated on the curved portion of its mutual characteristic curve. Under this condition the transconductance of the tube varies rapidly with variations in grid bias; that is, an increase in grid bias decreases the transconductance, and vice ve^sa. When the LIMITER CONTROL (potentiometer Ri34) has been properly adjusted, the modulation limiter provides a minimum: of 3 decibels compression at 100 percent modulation; this has the effect of raising the average modulation level approximately 7 decibels without exceeding 100 percent modulation on voice peaks. For the adjustment procedure for the LIMITER CONTROL see paragraph 197.
149. C-W Side+one
a. Sidetone Oscillator (fig. 83). Tube V106 (Tube JAN-6SN7 (VT-231) ) is connected in a multivibrator circuit. Its purpose is to generate a sidetone signal for monitoring the c-w transmission. When the transmitter is keyed, the cathode circuit
of tube V106 is completed to ground through the contacts on switch SW206B and relay RY20q. The multivibrator circuit is essentially a two-stage, resistance-coupled amplifier in which the voltage developed by the output of the second tube is fed back to the input of the first tube. Tube V106 is a dual triode tube and is self-biased as a result of the d-c voltage drop across the cathode-bias resistor Ri36. Capacitor Ci28 is the a-f bypass capacitor for resistor Ri36- Plate current flow through the left-hand triode of tube Vi06 causes a voltage drop across plate-load resistor Ri39. This voltage drop is applied to the grid of the right-hand triode through capacitor Cu8. This change of grid voltage produces a corresponding change of plate current and voltage drop across plate-load resistor Ri40. The voltage drop across resistor R140 is then applied to the grid of the left-hand triode through capacitor Cm. Resistor Ri35 is the grid resistor for one triode section; resistor RX38 in series with potentiometer R137 forms the grid resistor for the othei triode section. The frequency oscillation is determined by the values of coupling capacitors Ch? and Cji8 and the grid resistors. The audio output of the sidetone oscillator appears across potentiometer Rm-
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Figure 83. Sidetone oscillator circuit—functional diagram.
b. Sidetone Amplifier (fig. 83). Tube Vios (Tube JAN-6J5 (VT-94) ) is connected as a cathode-follower amplifier. Its purpose is to isolate the headphones from the sidetone oscillator and to provide a low-impedance output to which the headphones are connected. This stage, strictly speaking, is not an amplifier because theroetically the gain of the stage can never exceed unity and practically the gain of a cathode-follower stage is in the range of 0.6 to 0.8. In this type of amplifier, the plate of the tube is connected directly to B + ; and the cathode-bias resistor serves as the load resistor.
Resistor Ri22 is the cathode-bias resistor for tube Vios and also acts as the load resistor. Grid excitation voltage for tube Vios is obtained from the movable contact on potentiometer Rm which also serves as the d-c grid return to ground. Potentiometer Rm controls the volume level of the sidetone signal applied to the grid of tube Vio8; resistor Rm limits the maximum signal that can be applied to approximately two-thirds the available output of the sidetone oscillator. The output voltage appear -ing across Ri22 is applied to the headphones through resistor Ri4i. The output impedance of tube Vies
128
is approximately 300 ohms; accordingly, resistor Rm is connected in series with the cathode of
tube Viog and the headphones to provide a better impedance match.
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Figure 86. Dynamic microphone circuit—functional diagram.
through pin No. 2 on socket SOwi and relay RY2Oo. Capacitor CX23 is an r-f bypass to prevent high-frequency interference from entering the amplifier by way of the microphone cords. Capacitor C424 prevents sparking at the microphone switch contacts when breaking the d-c current through relay RY200. The DYNAMIC MIC. 1 control (resistor Rin) functions as a gain control for the speech amplifier when a dynamic miscrophone or field telephone is used to modulate the transmitter. (See fig. 79.)
c. Modulation Limiter Control. The LIMITER CONTROL (resistor Ri34) (fig. 82) is located on the front panel of the speech amplifier behind a cover plate. Its purpose is to control the amplitude of the a-f signal applied to the modulation limiter tube Vio5. The control is provided with a slotted shaft which is accessible when the cover plate is removed. See paragraph 197 for instructions as to the proper procedure for adjusting the modulation limiter control.
d. Sidetone Volume Control. The sidetone volume control (fig. 83) is located on the rear side of the speech-amplifier chassis. Its purpose is to
Section IV. THEORY OF
Note. Junction Box JB-70-A (fig. 124) contains all the electrical circuits necessary for the control of Power Unit PE-95-( ), Radio Transmitter BC-610-E, and Radio Receivers BC-312-( ), BC-342-( ). A-c power outlets are provided for Rectifier RA-63-(*), lights, heater, blower, etc.
152. Transmitter Control Switch SW203
a. General. The transmitter control switch SW203 is a three-position lever-key type of switch and is located on the front panel of the junction box. The switch is marked TRANS. ON TRANS. OFF REC. TO EE-8. The switch performs four major functions:
control the amplitude of the a-f signal applied to the grid of the sidetone amplifier tube Vio.
e. Auxiliary Key Jack. The KEY jack located on the front panel of the speech amplifier is connected in the cathode circuit of oscillator tube V8, located in the transmitter. The jack accommodates Plug PL-55. The transmitter can be keyed for c-w operation by inserting a key plug into this jack.
Caution: When the transmitter is keyed from this jack, the receiver disabling circuits do not operate. Therefore, be sure that neither radio receiver is tuned to the transmitter frequency or a harmonic thereof.
f. Modulator Plate Meter. The MODULATOR PLATE meter Mioi (fig. 62) indicates the d-c current to the Class B modulator tubes V3 and V4. Correct zero-signal bias to tubes V3 and V4 is obtained by adjusting the MODULATOR BIAS control (located on the front panel of the transmitter) while observing the indication of the meter. When modulating the transmitter, the microphone gain controls are adjusted properly by observing the indication of the meter on voice peaks.
JUNCTION BOX JB-70-A
(1) Applies 115 a-c volts to coils of relays RY4 and RY4.
(2) Connects coil of relay RY200 to KEY jacks or remote telephone line through contacts on switch SW202b.
(3) Connects remote telephone line through capacitor C202 and contacts on switch SW202c to input of speech amplifier.
(4) Connects remote telephone line through capacitor C202 and contacts on switch SW202a to the receiver outputs.
b. Trans, on Position (fig. 87).
130
(1) When switch SW203 is set to TRANS. ON and the REMOTE CONTROL EE-8 switch SW202 is set to NORMAL, switch SW203 performs two functions:
(a) Switch SW 2o3 applies 115 a-c volts to relays RYi and RY4. Relay RYX applies plate power to the transmitter; relay RY4 is the antenna shorting relay. See paragraph 142 for a detailed description of the functions of these relays.
(b) Switch SW203 connects one side of the coil of relay RY2oo to the KEY jacks located on the junction box. Relay RY2oo is keyed during c-w operation. For a detailed description of relay RY200 see paragraph 154.
(2) When switch SW203 is set to TRANS. ON and switch SW202 is set to either TELEPHONE position, switch SW203 performs three functions:
(a) Switch SW203 applies 115 a-c volts to relays RYi and RY(.
(6) Switch SW203 applies 12 d-c volts to the coil of relay RY200.
(c) Switch SW 203 connects the ungrounded REMOTE TELEPHONE terminal through capacitor C202 to the grid of the first a-f amplifier tube V101.
(3) When switch SW203 is set to TRANS. ON and switch SW202 is set to either TELEGRAPH position, switch SW203 performs two functions:
(a) Switch SW203 applies 115 volts a-c to relays . RYX and RY4.
(5) Switch SW203 connects one side of the coil of relay RY2Oo to the ungrounded REMOTE TELEPHONE terminal of the junction box. The transmitter can then be keyed from the far end of a telephone line connected to the REMOTE TELEPHONE terminals.
c. Trans. Off Position. In the TRANS. OFF position, all circuits to which switch SW203 is connected are open.
I POSITION OF SW202
■---9-----1 I. BC-312 TELEGRAPH
2. BC-312 TELEPHONE II/ || / 3. NORMAL
TRANS RYI 11(2 KRY4 4. BC-342 TELEPHONE
K K 5. BC-342 TELEGRAPH MICROPHONE
_____ I1Q7 IIW SWITCH
X " 7-------------------------------1------------------------------------H
TO X “I ||i-„ ■
TELEPHONE EE-8-C ) | C?q? 1+ v
INCHEST CH-120 "T" IMF 12V JZ. 101 VT-103
DC .Z"" ■'"s.
O 11 R|05 R|03 N
REMOTE ? I A A A_ a a a I_________1
TELEPHONE I 3 I 'QC 200M I /
9 26 j46 k—y
k>i I 56 J200 J
< SW202B --------------- j । M ANTENNA
Hi ,w .13 SHORTING I
/ O | ® " " ®---" (X) 20 (X> JUNCTION | I 3 RELAY |
/ L_ SW205B SW203 V jT jbB?70-Aj I [ I
I -------------. ^_Z_J | I | I |_L_ 1--------------1
MICROPHONE I I I
SWITCH _1_ 12V
— DC
I------------7
J~' —I T- ' — — — — —|। | RADIO *
। VIO6 VT-231 | | I . RECEIVER .
~~l r~ | | V8 |VT-IO7 I -------------1 SC-342-O I
i ZY i i । j
' Yf V ’ V I I Zry, ! I antenna I
I 1 c? C I 3 SHORTING
I —— ; i ,#p F Y ' I 7 "£LAY I
' 11—? ! ! ~ '
! 1 has S'"’ | ---------------’
1 Ssoon I | sioom 3iomh
I i i । 1 r "5V ’
I________ 1 I I 1 AC i
I SPEECH AMPLIFIER I | RADIO TRANSMITTER |
I___BC‘6I"’E _J L - BC-6I0-E
_ —------— — ---- —----> »(. ,44( 5
Figure 89. Keying relay RYsoo—functional diagram.
another pair of contacts completes the cathode 155. Receiver Disabling Switches SW200
circuits of the m-o or crystal-oscillator tube V8 and SW20l (fig. 90)
and the c-w sidetone oscillator tube Vi06. The Switches SW2oo and SW20i are double-pole, double-C.W. SIDETONE switch SW202Bis also connected throw toggle switches. When these switches are in the cathode circuit of tube Vioej its function is thrown to the ON position and relay RY2Oo is described in paragraph 157. energized, they perform two functions: One pair
c. Receiver Disabling Circuits. One pair of of contacts on switches SW200 and SW20i connects
contacts on relay RY2Oo applies 12 d-c volts (through
switches SW2Oo and SW20i) to the antenna shorting receiver
relays in Radio Receivers BC-312-( ) and disabling --------------------------
J t . I-- RADIO RECEIVER BC-3I2-C )
BC-342-( ). One pair of contacts grounds the —° / on 6 , output
audio output of Radio Receiver BC-312-( ) q ___________________________________<0_0_000y —
through switch SW200; another pair of contacts ry2Oo ° 'antenna'
ground the audio output of Radio Receiver () ° 0FF ? shorting —
BC-342-( ) through switches SW2Oo and SW20i.
See paragraph 155 for a functional description of -------------------
RECEIVER DISABLING switches SW2Oo and-----------------------------------------------------------------
SW2oi. Because of the close proximity of the receiver
receiving and transmitting antennas, the receiver ____o 0N (5 radio receiver bc-342-o
input circuits are subjected to large amounts of ____ / - - /
r-f energy when the receivers are turned to the °sw2oi xdQ-ZZL 1
ky200 ------------ I
transmitter frequency or a harmonic of the trans- o off o shorting ____
mitter frequency. Radio Receivers BC-312-( ) ' relay °dTa?udio
and BC-342-( ) are provided with antenna 111111 p"—____________________________
shorting relays. To prevent damage to the input —I— l2v°c Y2oo
circuits when the transmitter is operating, contacts ". ... ... , .. ,
07 r igure 90. Receiver disabling switches—functional
on these relays ground the receiving antennas. diagram.
133
i\ y
LOUDSPEAKER I_______________________________________________■ LOUDSPEAKER
LS-3 I _____ ___________________________________________ LS-3
IN CHEST CH-121 I /~^ L—\ IN CHEST CH-120
r _L __L_ \]
5
RADIO RECEIVER BC-3I2-C) RADIO RECEIVER 8C-342-O
OUTPUT OUTPUT --------
2D AUDIO » 2D AUDIO
0SW2O5A ^^OSA^ 0=
----0—R _ -----------* -
C.W. A203 205 c.w.
SIDETONE J202 P V ° " VV\-------4 Y P J204
J203 p\/-O O--Y p j205
<4 / 8 -NORMAL — HEADSETS BC-312 / / — HEADSETS BC-342
” OUTPUT A' Y TRANSPOSED
b 204 Tl 14491
Figure 91. RECEIVER OUTPUT switch—functional diagram.
12 d-c volts to the antenna shorting relays; the other pair of contacts grounds the a-f outputs of the two receivers. Switch SW200 (BC—312) disables Radio Receiver BC-312-( ), and switch SW20i (BC-342) disables Radio Receiver BC-342-( ). When these two switches are thrown to the OFF position, the antenna shorting relays are grounded. See paragraph 154 for the functions of relay RY20o. 156 * * * * * * * * * * * * * * * * * * *
156. Receiver Output Switch SW204 (fig. 91)
Switch SW204 is a double-pole, double-throw toggle
switch and it functions as follows: When switch
SW204 is set to NORMAL, the a-f output of Radio
Receiver BC-312-( ) is connected to the HEAD-
SETS jacks mounted toward the left-hand side
of the junction box and to Loudspeaker LS-3
located in Chest CH-121. The a-f output of
Radio Receiver BC-342-( ) is connected to the
HEADSETS jacks mounted toward the right-hand
side of the junction box and to Loudspeaker LS-3
located in Chest CH-120. When switch SW204 is
set to TRANSPOSE, the a-f output of Radio
Receiver BC-312-( ) is connected to the right-
hand HEADSETS jacks and to Loudspeaker LS-3
located in Chest CH-120. The a-f output of Radio
Receiver BC-342-( ) is connected to the left-hand
HEADSETS jacks and to Loudspeaker LS-3
located in Chest CH-121. By the use of switch
SW2o4, the operator at Radio Receiver BC-312-( )
can instantly switch his loudspeaker and headsets to the output of Radio Receiver BC-342-( ), and vice versa. Switch SW204 does not effect the functioning of the RECEIVER DISABLING switches^ The a-f signal applied to the HEADSETS jacks is attenuated an appropriate amount by resistors R2o3 and R205. These resistors also serve to isolate the headsets from the receiver output circuits to prevent grounding the c-w sidetone signal when th6 receivers are disabled.
157. C.W. Sidetone Switch SW205 (fig. 92)
Electrically, switch SW20s is a two-section, threey position switch. Its purpose is to complete the cathode circuit of the c-w sidetone oscillator tube V106 and to switch the c-w sidetone signal output of the sidetone amplifier tube Vi08 to either pair of HEADSETS jacks. When switch SW20s is set to position 1 (TO BC-312), the A section applies the sidetone signal to the left-hand HEADSETS jacks of the junction box; when the switch is set to position 3 (TO BC-342), the A section applies the sidetone signal to the right-hand HEADSETS jacks. i
- - . i
158. Start-Stop Switch SW206 (fig. 93)
Switch SW206 is used to start and stop Power Unit PE-95-( ). When the START button is pressed, current from the 12-volt battery m the power unit hows through the starting relay in the power unit.
134
-■V.os i , HEADSETS HEADSETS
>4-------LvT-231 BC-312 C.W BC-342 V|08_____*
Z^Jii J202^V——O SWITCH O ——vjj J204 \
' Lzz; J2O3[t- ...... <:—T205 \Xy
‘ j -- f' sw205A I----------------------
- ; — 5M
' 1*122-
I | 2M
RI36 | J Q2 ]3 ~
-----------------mw--------------1-----d d
500A | x^''oSW205B
POSITION OF (A .
SWITCH SW2Q5 I f
I. TO BC-312 !
2. OFF- ’ J-------------------------------------,
a TO BC-342 (A RY I
A RY2OO +|
i TLJ4492
Figure 92. C. W. SIDETONE switch—functional diagram.
Contacts on the starting relay complete the starting circuit and start the motor of Power Unit PE-95-( ). When the STOP button is pressed,
POWER UNIT JUNCTION BOX
_p£-2^r£ X___ ______
START RELAY I *
rW-------------;------)----1
LsTART
’ SW206A
12 V DC I I
—d'H-J-l—j—
I o\l STOP
_____ । I sw206B
-------------1-----
STOP RELAY |
L__________________j l_________________________1
TL 14486
Figure 93. ST ART-STOP switch—functional diagram.
current from the 12-volt battery flows through the stopping relay. Contacts on the stopping relay short-circuit the ignition system and stop the motor of Power Unit PE-95-( ).
AUXILIARY
POWER UNIT BATTERY
PE-95-1 ) BATTERY CHEST CH-IO9-A
f— ----1 SOURCE I------'
SWITCH I '
sw207
I-- ■■ ■ ex o--------------'-.
+ | PE-95 \ AUX I +
12 V "A- I -A- |2 v
DC | ! = OC
-'Ll-----—-------------------------It- I
l—_□ q_„j
TO ALL CIRCUITS “
REQUIRING 12 VOLTS
DC FOR THEIR OPERATION TLI4493
Figure 94. Battery source switch—functional diagram.
159. Battery Source Switch SW2a7 (fig. 34)
Switch SW207 is a single-pole, double-throw toggle switch. When switch SW207 is set to PE-95, the 12-volt storage battery located in the trailer with Power Unit PR-95-( ) is connected to all circuits requiring 12 d-c volts for their operation. When switch SW207 is set to AUX., the 12-volt d-c circuits are connected to the 12-volt storage battery in Chest CH-109-A. The negative terminals of the storage batteries are grounded and the positive terminals are connected to switch SW207.
160. Circuit Breaker CB 200 (fig. 124)
Circuit breaker CB2oo is designed to break a current in excess of approximately 50 amperes. One side of the 115-volt a-c line from Power Unit PE-95-( ) is common to all equipment. The other side of the line is connected to the equipment through circuit breaker CB2oo. The normal current required by the equipment passes through the circuit breaker without interruption; however, a short circuit on the line, or a load in excess of 50 amperes trips the circuit breaker. The circuit breaker can be reset by pressing the PRESS TO RESET button on the front of the junction box. When switch SW205 is set to position number 1 or 3, the B section grounds the cathode resistor Ri36 of the c-w sidetone oscillator tube V106 through a pair of contacts on relay RY2Oo. When switch SW205 is set to position number 2 (OFF) the c-w sidetone circuits are open.
161. Surge Filters
When the circuit to a coil carrying a current is broken, the magnetic field about the coil collapses. The collapsing magnetic field induces a back emf
135
(electromotive force) in the coil that is proportional to the product of the inductance of the coil and the time rate of change of the current through the coil. The current through the coil changes very rapidly at the instant the circuit is broken; accordingly, the voltage induced in the coil may reach extremely high proportions. In a circuit containing
200 ______
ft™ * ft00
/ \ T- (x)SW203
/ \ ±200
z / 1 iR201 iTZ/ n JACKS
ecftift200! 342iife l,oon R2oft
If 100 ±C2oo IP ±C2OI ,00n| ' J20'
S_____J-0.01 MF h____J-O.OIMF
' R204-L
P.PIMF^
Ve << I yT-107
G>ch2 to I MH
(----j RY200
J 0>CH9 ---------6<)-------
R35> to 10 MH
(OOM | to
fl R 202
I |------------------------1
C203 Tt|449»
0.01 MF —
Figure 9'5. Surge filters—functional diagram.
inductance, a dissipative network is connected across the coil to prevent arcing at the contacts of the switch which breaks the current. This network, sometimes called a surge filter, consists of a resistor in series with a capacitor. In Junction Box JB-70-A there are four of these dissipative networks. (See fig. 95.) The action of a surge filter can best be shown by an example. When the transmitter is keyed for c-w operation, the current through relay RY200 is interrupted in accordance with the dots and dashes to be transmitted. When the current is interrupted, the back emf induced in the coil of relay RY2oo charges capacitor C204 through resistor R2o4. Capacitor C204 then discharges back through resistor R204 and the coil. However, the resistance of the coil together with resistor R204 is high enough that only a few highly damped oscillations occur and the transient voltage dies out in a very short period of time. Thus the back emf, induced in the coil at the instant the current is interrupted, is dissipated in the form of heat in resistor R204 and the resistance of the coil. The antenna shorting relays of Radio Receivers BC-312-( ) and BC-342-( ) are provided with surge filters consisting of resistor R2oo with capacitor C2Oo and resistor R20i with capacitor C20i. Because of the inductance of choke coils CH2, and CH9 in the cathode circuit of oscillator tube V8, a surge filter is required. This filter consists of capacitor C203 and resistor R202.
Section V. OVER-ALL SYSTEM FUNCTION
162. General
Figure 96, an over-all system block diagram, shows the complete function of Radio Sets SCR—399-A and SCR-499-A. The major components of the radio set are: Radio Transmitter BC-610-E, Antenna Tuning Unit BC-939-A, Speech Amplifier BC-614-E, Junction Box JB-70-A, and Radio Receivers BC-312-( ) and BC-342-( ). The signal paths are as shown in figure 96.
163. C-W Operation
The transmitter uses a master or crystal oscillator which is keyed for c-w operation. To key the transmitter Key J-37 is connected to either KEY jack of Junction Box JB-70-A. The output of the oscillator is applied successively to the bufferdoubler, the i-p-a, and the p-a stages. The r-f power output of the p-a stage is approximately 400 watts in the 2- to 8-mc range, 300 watts in the 8- to 12-mc range, and 275 watts in the 12- to
18-mc range. The r-f output of the p-a stage is coupled to the transmitting antenna by means of Antenna Tuning Unit BC-939-A. Plate and screengrid voltage for the oscillator buffer-doubler, and i-p-a tubes is supplied by the exciter power supply; plate voltage for the p-a tube is supplied by the high-voltage power supply; bias voltage for the i-p-a and p-a tubes is supplied by the bias power supply. The sidetone oscillator in the speech amplifier operates when the transmitter is keyed, and the output of the sidetone oscillator is applied to the sidetone amplifier. The output of the sidetone amplifier is connected to the HEADSETS jacks in the junction box through the C.W. SIDETONE switch. Keying the transmitter operates the receiver disabling circuits when the RECEIVER DISABLING switches in the junction box are set to ON. Figure 97 is a functional schematic wiring diagram of the transmitter, speech amplifier, and junction box for c-w operation.
136
ANTENNA TUNING UNIT
.BC-939-A
r--------------------”--------------------- y...-.-...-...- ~ -- -I- - -------------------------------- "I
. I PA I
u I
| (VT-IOO)
I TWO .
j ---------------- ------------------ JAN-807 IN --------±7-----
I MO OR CRYSTAL BUFFER DOUBLER dadai i ri PA
• OSCILLATOR r PARALLEL Z~^. ______________ |
I F (220) *--*----’ h|oh-voltage
( I \ 115 J IVT-100) \. 7 POWER SUPPLY
। \ IOIJ \ j x ' x'—x. 1
JAN^6V6 JAN-6L6 ------ JAN-25OTH ( VT-\ |
. I ]- | o g T ‘ (4 6-A/ .
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| ' '---•---•-----•--J--- •---- •--•-* ° MODULATOR STAGE .amLa^a im I
,___________|_________o z^^x z-—JAN-866A IN I
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I Dino \ d. I O J \d\Ol --
I POWERSUPPLY V_Z X__Z /VT-\
I __ __ Z------X Z^X O< TWO JAN-IOOTH ( )
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I --- %___Z JAN-5Z3 DRIVER STAGE 1
’ THREE IAN-A71 Z~X Z~X '
I JAN-OD3/ VR -150 1______ ___ /VT-\ /VT-\ 1
I -------— ---------------- • * ~ \95 \ (95 )
TWO JAN-2A3
| RADIO TRANSMITTER BC-6I0-E ----——PUy ~PULL--- -|
SPEE^H AMPLIFIER (speech AMPLRl I legend:
°14’ L POWER SUPPLY I
rx । -------------- _ -------------- •------•---- PLATE VOLTAGE
DYNAMIC S\________, _________ IST A-FAMPLR (vT-eo) T ATH A-F AMPLR | o VOLTAGE
MICROPHONE VULIA(jt-
T-50 rf/ I (VT-IO3) I ( VT-231 ) I ---------- STAGES COMMON
\. 1 JAN-80 4 X Z I T0 CW AND
I___________----------------------------'to duXTT^ode 1 --- PH0NE operation
D1 JAN-6SQ.7 'mODULAt’i’oTTIALL JAN-6SN7GT | --- STAGES USED ONLr
^>00000 LIMITER STAGES 1 FOR PHONE OPER-
------1---REMOTE----—t o ---- "* I__________ 1 ---- ATION
I TELEPHONE 2D A-FAMPLR ( 033 ) 3D A-FAMPLR AND --- STAGES USED ONLY
EE-8-C) . X. J -PHASE INVERTER FOR C-W OPERATION
I IST A-F / VT-23TX I ---------
AMP. (VT-941 JAN-65R7 ( DUAL )
| J) W y \TRIODEJ |
JAN^6J5 -----*----------*■-- JAN- 6SN7GT .
I I ----------------“I |----- LU
ss. „„ । 3'-™= 1 jss;:0
OSC । O5C AMPLR
RADIO KEYING Z X Z^^ . RADIO
RECEIVER CIRCUIT _ I (vT-23l) ---•--- ( VT-94) 1 | RECEIVER
BC-3I2-O *“ X.__Z V / | BC-342-O
OUTPUT ~l 1 DUAL TRIODE IAM Kle . ___ OUTPUT
2D AUDI0 I JAN-6SN7GT ____JAN-6J5--- | 2D ^UDIO
, RECEIVER L2_____________ .RECEIVER ’’ -------------
DISABLING L_ _ ______ _ ___________ ___________ ___| DISABLING r
LOUDSPEAKERl\n CIRCUIT . CIRCUIT -* ,, riZ^l LOUDSPEAKER
LS-3 [JJ—— L - - ...1---------------------p pLkj LS-3
------------•--------- ------------------------- ‘ TELEPHONE
TO -----------------4----- JUNCTION BOX --------------------------------- EE-8-C)
REMOTE < » «__________________ JB-70-A ______________________r- IN
TELEPHONE o O CHEST
EE'e“’
HEADSET HEADSET
HS-30 \ HS-30
Figure 96. Radio Sets SCR-399-A and SCR-499-A—~complete block diagram.
I SPEECH AMPLIFIER j B+ i | ---------------- TO BUFFER-DOUBLER i--—--------------—
| 8C-6I4-E r * I R j ' V8 VT-|07 AND I PA STAGES V|6 I VT-2 20
I 5M< <5M I I /-1— \ TO
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। , "f tom । ,/?<“» " 4- I_________________LA
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I BC'312 I । *a । T? s*------------------t-----
i —•—U' । 1 g R/~l S | IHry5 .______________S’ ,ih
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I _______H'. I ?-----------------RV,||| T of
1--------3 II /II ___ C|9-L -Lc23
1 g ry2°° i 1 ±Ry2 ------------------r 3mFT T3mf
RECEIVER +I2V ANTENNA f i I Y \ —T— J
OUTPUTS DC SHORTING 1 i .______P----- V7V1XVT.4(1A
relays । 1 r n -----———'
| I | ill RY. -----------------------7------ — —
I J200 I I , o? S T .__________, EXCITER
kpyJ -----------------1 '____________II ? ?nv 5 J v , , I----^573---*-------•-----STAGES
KEYS. || ,, , , f-------- • RY L r l2ZTX 6H I I B +
J'37 i n 4-1-0------1—।----------------- a E f yr-l t4iiEJ Ar4
I 11- „ SW203 I | I g---- ( <) r $ 750,0 kR|O
i J2oi-X AT trans-°n । । a g \yry~i—-S 8i65mf I >40M
I । । _______| [__ ~a'7MF
JUNCTION B°x । | RADIO TRANSMITTER ___________________1________Ta'5MF
JB-70-A J । BC-6I0-E
Figure 97. Radio Sets SCR-399-A and SCR-499-A for c-w operation—functional diagram.
137
138
r R|30 a- - ■— i
i-----II "4 -«------VW----► B+ BUFFER DOUBLER _L?i2 2'5rk7^4
T IIO.OIMF | 5OM fi ZH X AND I PA Z^P\ x-p 0 0 1 ----*.
k| ,----1 I v,„ _AAA I I ( A A a9a i SjC'TO ANTENNA
3 £> I ✓—rx 105 rVW—। —I----I ----) r'V\AA3K tuning unit
S 3 I______4-X-Yt-223 CHg l00M CH2 \ r-. 7 \/\/ -Lr =4=TOOn 33 t
3 (gP -----L --------' *8 Vl6 C|2 o'oQ2MF .
3 3 \Jf Q 2.5MH I MH -107 VT-220 -----------r <-7
E/^r MICROPHONE | LIMITER CONTROL 0.006MF
13 T-50 B+ + R|33 /'POOH ,,R|34 _ _______ ___________________
nJ a L\mh >—t—vw---------------------- z4-x4
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_______>200M 1------1 RII3 IiOjOIMF____>R* V/V/ K ^P3!- VT-^/is >R"7 >R|IB Z^\V1°< o} C if T, 3 Jo f T3 illg RY3Q
RIO2 ZJ- X o.OIMfT f /-*■ \00IMfF--f---1 >00M>250M II--|VT'231 3 K 3 £> =3^ 3 3 E=? 3 S I ?1
, , s0|°lj. f-vvv-r-4---) —i—M— J —r-cz J r I zn-4—i r3 3 3 — ■zyfix. .-<3 — ■-<757p^> 3 4___?
331— 2/fPK3 < imeg < \ ।—\ r—7 I----1----f—I rt--I 3 3 3 3 ----3 43 3 ----~ 3 3
H ?E IT ) R|°® j—^102 R|I9s sR|2° 3 3 °) 3 Jri5 ’ 3 3 Jr 3 3
I J X3' ZIMEG200MZ < 0.0IMF C||9< 200M < VT-94 i>--1 250MX S250M ---v ' -------' I Z™ —, r— f ] > 17 I—. , I I
1 ? rI04 I X S 2Ox
>'-ooon IR|" r°°°n r"4> xSn >ru6 |[ B+ | > I y0M L''} i—:-------
RnX 2 S SrTSIO°M C|°6 ---" V 7V2 t J
l,000fl< CARBON La A A.__ I I I-------*JI-------_gIO7>RI2| \^CZvT-95 \2)
,, _f MICI NAiMEG "--- X O.OIMF “IlOMF 55OOn R v4
V>SW2O2C T B+ > [ Uz? SR2° VT-218
1 ..— --------j--------------—M--------------------------—1 nvo >750n -----"
< R||0 ==Z0 ==10 25M
PLUG PL-68 JI02 .. T005 f2000 UTA A A A J ---TO----------X ‘ ”
[f^ -f Q J” rrti_______________________________________________________
3000 JT ■ MODULATOR BIAS L
SPEECH AMPLIFIER BC-6I4-E I V
— BIAS TO TUBES EXCITER STAGES
__________________ _____________ -------- --_______ V|0 V(| AND V|6 B+ __________________________ _____________- ___________—— --- L| 4 , ,_______________RADIO TRANSMITTER BC-6I0-E______. -------------J8 ,-----------,
~L _ , ___।______________________ 3 3 *i2 I-----3 6R >o >=
L f 1 r~° __ ~ 3 3 VT-I45/^LX1 T4||/ 3 3 fen v x i72 =Ui9 4423 <75w
LZ__L_________T V VT-746a(^Y---------J 3MF 3MF
___I—
I -------------------------------------------jniw*
Figure 98. Radio Sets SCR-399-A and SCR-499-A for phone operation—functional diagram.
REMOTE. OPERATION CW OR PHONE
REMOTE + 12 V DC VIOI | I | v8
TELEPHONE CONTROL 4 VT-IO3 ZTX .XAtXvT-107
LINE \ EE-8 _______o /<—
\ _____ j T-----------7--0------ "102 / \ f____\
------------ JUNCTION BOX \ *------------------- f-A/W------f---(— I f I J8-60-A \ Sw2O2B S ry200-----J 1MEG J----------------------------1S 7/
Aoi ?——p—A- — ' k. 3 H 5R|01 >rio3 f—' r—s
TELEPHONE __________II . I I I । ~—I S I MEG <,200 J J CH^
rr q , . II i ] REMOTE C„n0 1 „ f M > o_ fc> 2
EE~8 ( ’ IMF uj | I TELEPHONE _L202 « ।---o—1—|-SW203 AT Ci30 R|°4 < RIO6 U |MH
________________ | I 1 I TTmF . _________________________ TRANS ON__---------------------'“AAA/-----" A 1,0000 S J30! t n jilt_____________________________UJ SW2O2CpTL _____________ ~ToOO5 YY _L GCH9 r ------------ o--------------____________________________________________ ■==’■ ____ i.ooon----------------S > 3 < PpL-55 "____________________________* 0.006MF ” I
□ JUNCTION BOX JB-?O-A SPEECH AMPLIFIER BC-6I4-E RAOlO TRANSMITTER 1
3: ,n_____________r ____ BC-6I0-E
I J-45______________ ___________________________________________________________
TELEPHONE EE-8-( ) IN CHEST CH-I20-A
POSITION OF SW2O2 I BC-312 TELEGRAPH -----------------------
2 BC-312 TELEPHONE 3 NORMAL REMOTE OPERATION ---------------
4 BC-342 TELEPHONE RECEIVERS TO TELEPHONE RADIO RECEIVER
5 BC-342 TELEGRAPH __________________________________________EE-8~( ) BC-3l2-( )
------------------------------------------------------- OUTPUT
-----------------------------------------2D AUDIO
REMOTE RECEIVER
CONTROL OUTPUT A
"1 _ E"EE-8 sw204 r____________________________—/loudspeaker
TELEPHONE |02° 61 404 [ LS-3 IN
LINE °bw2O2A I NORMAL "-----LI CHEST CH-I2I-A
------------ JUNCTION BOX \ cl --------- ■JB~60~A------------------------ 3 I , 202 TRANSPOSE/ \--------------------------RADIO RECEIVER I
I 11 IT rtAUIU ntUtlvtn
,1 501 ? p" II--------------------0--^-r J J BC-342-( )
TFIFPMONF II II IMF I-- lew r203 > >R2O5
TELEPHONE ’.n-re A__ i sw203 5M < < 5M OUTPUT
■ EE-8-1 ) IMF z I I REMOTE AT RFC 5 > ? 5 —2D AUDIO
----------------1 □ I ; TELEPHONE ____1 TO EE-8 >______________>_________-------------------------------- i______________________I ' p .________--------- _________________, /I LOUDSPEAKER
----------------------------—J I J ' • LS-3 IN -------- --------------------d_ —p I 11 ------------------LI CHEST CH-I20-A j---------------------------- ’ J2O2 ? I ? J204
TELEPHONE EE-8-( )______________ > > >
—1 J203 cd cd cd tzd J205
IN CHEST CH-I20-A------------------
_________________________JUNCTION BOX__JB-70-A_________________________ni«4M
HEADSETS HEADSETS
BC-3l2-( ) BC-342-( )
Figure 99. Radio Sets SCR—399—A and SCR—799—A for remote operation—functional diagram.
139
140 ’
164. Phone Operation jack of Junction Box JB-60-A. The a-f output
For phone operation, the transmitter oscillator °f the Telephone EE-8-( ) is used to modulate
produces continuous oscillations which are applied the transmitter for remote phone operation. The
successively to the buffer-doubler, i-p-a, and p-a operator at the remote, station can hear signals
stages. The r-f carrier output of the p-a stage is received by Radio Receiver BC-312-( ) or BC-
approximately 300 watts when operating in the 342-( ) when the transmitter control switch SW203
2-to 8-mc range, 250 watts in the 8-to 12-mc range, is set EEC . EE-8. The output of either
and 200 watts in the 12- to 18-mc range. The r-f receiver is selected by the REMOTE CONTROL
carrier is amplitude modulated in the p-a stage EE-8 switch SW202a. Telephone EE-8, located
(plate modulation). The transmitter can be modu- Chest CH-120-A, is connected to the telephone lated approximately 90 percent by a carbon Micro- l^e, and provides telephone facilities between the phone T-17 or T-45 or a dynamic Microphone remote station and shelter.
T-50 connected to the CARBON MIC. 1 and b- Junction Box JB-60-A provides a convenient DYNAMIC MIC. 2 jack and socket, respectively, means of connecting a remote field Telephone
of Speech Amplifier BC-614-E. Microphone T-50 EE-8-( ) and Key J-45 to a telephone line. Key
connects to the input of the first a-f amplifier; Jack *Eoi is connected across the LINE tormina s.
Microphone T-17 or T-45 connects to the input This Jack accommodates Plug PL-55 and is used
of the second a-f amplifier. The output of Micro- with key J-45 to key the transmitter. The short
phones T-17 and T-45 is amplified by the second, two-conductor rubber-covered cord entering the
third, and fourth a-f amplifiers; the output of junction box through a rubber grommet marked
Microphone T-50 is amplified by the first, second, EE-8 connects to field Telephone E 8 ( ).
third, and fourth a-f amplifier. A portion of the Capacitor C301 prevents Telephone EE-8 from
output of the third a-f amplifier is applied to a short-circuiting jack J301, and m addition, serves
modulation limiter. The modulation limiter pro- as a low-impedance path for the telephone ringer
duces a d-c bias voltage which reduces the gain voltage and voice fiequencies.
of the second a-f amplifier on extreme voice peaks
x x J i .■ t , 77, JUNCTION BOX JB-60-A
to prevent over modulation of the transmitter. ,------------------------------.
The speech amplifier power supply furnishes plate I |
and filament voltage for all tubes in the speech j 0 j0| LINE
amplifier, and current for a carbon microphone. -------1|---------Q
The output of the fourth a-f amplifier is applied to I I MF
the push-pull driver stage in the transmitter. The To I_____ J30l
driver stage develops the a-f voltage and power TELEPHONE ] O—% Fl key
required to drive the push-pull Class B modulator. EE-8-( ) ----■----- ------U
The a-f output of the modulator stage is combined
with the r-f carrier in the p-a stage to produce the |_________________j_____q
amplitude-modulated r-f wave which is radiated । LINE
from the transmitting antenna. The microphone
switches operate the transmitter and the receiver ।______________________________I
disabling circuits when the RECEIVER DIS- C301 200 V DC TL 14495
ABLING switches in the junction box are set to Jmction Bm JB_e0_A_fmctional '
ON. Figure 98 is a functional schematic diagram diagram.
of the transmitter, speech amplifier, and junction
box for phone operation. 166. Rectifier RA—63—(*)
Rectifier RA-63-(*) operates on an input voltage 165. Remote Operation (fig. 99) of 105 to 125 volts, 50- to 60-cycle alternating
a. The transmitter can be keyed for c-w opera- current. The rectifier furnishes a d-c output voltage
tion or voice modulated for phone operation from sufficient to charge the 12-volt storage battery in
a remote station located as far away as 1 mile. Chest CH-109 at a 5-ampere rate when the battery
The remote station consists of Telephone EE-8-( ) is in a completely discharged condition. The recti-
and Junction Box JB-60-A, and is connected to fier is equipped with a cord and plug ,cor connecting
the REMOTE TELEPHONE terminals of the it to Junction Box JB-70-A. A-c voltage is applied
junction box by means of Wire W-110-B. To key to the primary winding of transformer T50 0 through
the transmitter, Key J-45 is connected to the KEY circuit breaker CB50o and control switch SW2Oo-
14!
(See fig. 101.) The circuit breaker protects transformer T5Oo from damage if the secondary circuit is subjected to a short circuit or overload. The circuit breaker can be reset by pressing the red PRESS TO RESET button. The rectifier can be turned on or off and the charging rate can be controlled by switch SWsoo- When the switch is set to TRICKLE, the rectifier provides a trickle charging current of approximately 0.5 amperes into a fully charged battery. When the switch is set to FULL CHARGE, the rectifier furnishes a current of approximately 1.5 to 5 amperes, depending on the condition of the battery
and the dry disk rectifier RA5Oo. Rectifier unit RA5Oo is connected in a full-wave bridge-type rectifier circuit. The secondary winding of transformer T500 furnishes a-c voltage to rectifier RA500 and relay RY500. When the power is turned on, relay RY5Oo is energized and the relay contacts close. The d-c output of rectifier RA500 is applied to the d-c terminals of plug PL500. When the power is turned off, the relay contacts open and prevent the battery from discharging back through the rectifier.
r-------—™ 1
ra500 trickle
! ° oFFo^^'b—1 sw500 I pl500
rC — 11—i zfcn
3 £ CHARGE I
y-------------; 1 j rOi
t500 (k I
/ cb500> I _
ry500 TS500
-------0-p
j H-H-J--------
_____________________________fi-oJ-1-
j-U-j
_________________ ,..?l Q-!_■_ I--------------------------J | CD5qq
j______________T- -.-pr- -____=_____J
TL 16408
Figure 101. Rectifier RA-63-(*)—functional diagram.
142
Section VI. CHANGES IN EQUIPMENT
167. Changes in Radio Transmitter BC-6I0-E
a. Rectifier Filament Transformer T2. Beginning with serial number 5191 on Order No. 30204-Phila-43, a change has been made in rectifier filament transformer T2. This change was necessary to prevent break-down caused by arc-over in the transformer. A hermetically sealed transformer with ceramic stand-off terminal insulators (Signal Corps stock No. 2Z9611.144) has been substituted for Stancor type 10P34 (Signal Corps stock No. 2Z9611). The new transformer does not have a secondary center tap and requires connection of the positive high-voltage lead to one of the 2.5-volt filament terminals. For equipments manufactured before the change was made, MWO SIG 11-281-4 applies.
b. Plate Power Relay RYi. Beginning with serial number 1353 on Order No. 30203-Phila-43, and serial number 5191 on Order No. 30204-Phila-43, a change has been made in plate power relay RYV This change was necessary to prevent failure of the transmitter due to arcing and sticking of the plate power relay contacts. An industrial contactor type relay, Allen-Bradley type A-209 bearing Hallicrafters part No. 21D056, is used to replace the Leach type 1154 relay.
c. Neutralization High-Voltage Isolation Capacitor C29. Beginning with serial No. 5003 on Order No. 30204-Phila-43, capacitor C29 has been changed. This change was necessary to prevent failure of capacitor C29 due to the extremely high r-f potentials to which it is subjected during tuning of the transmitter or during periods of accidental overmodulation. The modification provides a capacitor of higher voltage rating, which prevents flash-over on the adjustable neutralizing capacitor Cis and injury to operating personnel by assuring complete isolation of capacitor Cis from the high-voltage d-c circuit. The original capacitor C29, a Sangamo type HIL 0.001-mf, 2,500 d-c volts (working) Signal Corps stock No. 30A1-80, is replaced with an American War Standard capacitor CM-70-B201-J, 200-mmf, 5,000d-c volts (working), Signal Corps stock No. 3K7020122. For equipments manufactured before the change was made, MWO SIG 11-281-5 applies.
d. Filter Choke Li. Beginning with serial number 5191 on Order No. 30204-Phila-43, filter choke Li has been changed. The redesign of choke Li was necessary because of excessive temperature rise. A new filter choke Li Hallicrafters part No. 56C043, is used to replace the original choke Lb
Hallicrafters part No. 56B018. The new choke has the same base-mounting dimensions but is slightly higher than the original unit. Therefore, it is not interchangeable with the original choke unless switch S Wio is removed, e below.
e. Interlock Switches SW2, SWio, SW13, and Circuit Wiring. Beginning with serial number 5191 on Order No. 30204-Phila-43, interlock switches SW2 and SW13 and the circuit wiring to these switches has been changed. Interlock switch SW10 has been removed from the transmitter since it performs no necessary function, and because additional space is required for the new choke coil Li (d above). Interlock switches SW2 and SW10 have been changed to open type contactor switches capable of breaking the primary current to the high-voltage plate supply transformer T6. In addition, these switches have been rewired so that opening of the access doors breaks the primary circuit to the high-voltage plate supply transformer Tg instead of the circuit to the plate power relay RYi. (See fig. 73.) This modification of interlock switch wiring is necessary to prevent injury to operating personnel resulting from failure of relay RYi to open the high-voltage when the relay contacts freeze or stick.
Figure 102.' Mounting of tubes Ve and Vi before , modification.
f. Mounting of Rectifier Tubes VT-46A. When operating Radio Transmitter BC-610-E in dusty localities, large amounts of dust may ac
143
cumulate underneath and around the sockets for high-voltage rectifier Tubes VT-46A. This accumulation of dust can absorb moisture and cause flash-over from high-voltage terminals to ground. To facilitate cleaning of the tube sockets and to prevent failure of the transmitter due to flash-over, rectifier Tubes VT-46A can be remounted. Figures 102 and 103 show the original mounting and remounting of rectifier Tubes VT-46A, respectively. For equipments that show symptoms of the above trouble, and have not already been modified, MWO SIG 11-281-2 applies.
amplifier tube Vios remains connected to the junction of resistors R126 and Rm-
b. An improved replacement for dual electrolytic capacitors, reference Nos. C108, 109, (Til, 115, and C112, 113 in Speech Amplifier BC-614-E have been procured and are now available for requisition from the field. The improved capacitor, Signal Corps stock No. 3DB8-117, should be requisitioned and installed in place of the original, Signal Corps stock No. 3DB8-35, whenever replacement becomes necessary.
Figure 103. Mounting of tubes Vs and V? after modification.
a126 new lead
--- --------o------WAAAz-------------
20 M X
4 I ft RI25
C||| FORMER ft ft 75M
“T~ 8MF lEAD J> ft <
139 ft ft 140 5m ft ft 5m
V|08 VT-94 Vl06 VT-221
\ I y x r \P
ft 138 ft 50M I
5 *137 ioom
TL 13808
A.
Figure 104. Diagram of change in sidetone oscillator circuit.
168. Changes in Speech Amplifier BC-6I4-E
a. Beginning with serial number 1151 on Order No. 30203-Phila-43, a change has been made in the c-w sidetone circuit. The change increases the available sidetone signal level and compensates for a possible loss in signal level due to circuit element deterioration. The plate-voltage supply connection for tube V106 has been changed from the junction of resistors R126 and Rm to the junction of resistors Ri25andRi26- (See fig. 104.) This change increases the plate-voltage to the sidetone oscillator tube V106. The increased plate voltage results in an increase in output of the sidetone oscillator tube Vio6- Resistor Ri38 has been changed from 100,000 ohms to 50,000 ohms. This change increases the level of the sidetone signal available at the sidetone volume control Rm slightly more than 2 db (decibels). The plate-supply lead for sidetone
169. Wiring Change in Junction Box JB-70-A If operation of RECEIVER DISABLING switches SW200 and SW201 does not provide disabling of Radio Receivers BC-312-( ) and BC-342-( ), respectively, regardless of the position of RECEIVER OUTPUT switch SW204, the switches are incorrectly wired. (See fig. 105.) On an incorrectly wired Junction Box JB-70-A, operation of RECEIVER OUTPUT switch SW204 transposes the disabling action as well as the audio output of Radio Receivers BC-312-( ) and BC-342-( ) (except when RECEIVER OUTPUT switch SW204 is in NORMAL position). Such method of operation of these switches is undesirable. Correction in wiring of Junction Box JB-70-A to eliminate this fault was accomplished in production after approximately 200 Radio Sets SCR-399-A had been shipped on Order No. 14153-Phila-43.
144
Radio Sets SCR-499-A were shipped with doublet antenna kits (on Order No. 18372-Phila-44) before the coupling coils were changed. These radio sets bear serial numbers 1 to 17 inclusive, 19 to 41 inclusive, and 43 to 87 inclusive. The doublet antenna kits supplied with these 85 radio sets are equipped with Coil Units C-451, C-452, and C-453. These coupling coils are designed to fit inside the p-a tank coils of the transmitter. The desired degree of coupling to the antenna is obtained by moving the coupling coils in or out of the p-a tank coil.
b. All doublet antenna kits except those mentioned in subparagraph a above are supplied with Coil Units C-387-D, C-388-C, C-389-C, C-390-C, C-447-B, C-448-B, and C-449-B. These coil units have a variable coupling link and replace the fixed link p-a tank coils previously supplied with the transmitter.
c. As soon as circumstances will permit, Radio Sets SCR-399-A and SCR-499-A will be delivered with the variable link tank coils listed above instead of with the old fixed link tank coils. When the doublet antenna kit is issued for use with such sets, either the oils will be omitted from the kit or, if issued, should be returned to stock.
Section VII. TROUBLE SHOOTING
171. General Trouble-Shooting Information
No matter how well equipment is designed and manufactured, faults occur in service. When such faults occur, the repairman must locate and correct them as rapidly as possible. This section contains general information to aid personnel engaged in the important duty of trouble shooting.
a. Trouble-shooting Data. Take advantage of the material supplied in this manual to help in the rapid location of faults. Consult the following trouble-shooting data when necessary:
(1) Block diagram of Radio Sets SCR-399-A and SCR-499-A. (See fig. 96.)
(2) Complete schematic diagrams. (See figs. 120 through 124.)
(3) Simplified and partial schematic diagrams. These diagrams are particularly useful in trouble shooting, because the repairman can follow the electrical functioning of the circuits more easily than on the regular schematics, thus speeding trouble location.
(4) Voltage and resistance data for all socket connections.
(5) Illustrations of components. Front, top, and bottom views which aid in locating and identifying parts.
(6) Pin connections. Pin connections on sockets, plugs, and receptacles are numbered or lettered on the various diagrams.
(a) Seen from the bottom, pin connections are numbered in a clockwise direction around the sockets. On octal sockets the first pin clockwise from the keyway is the No. 1 pin.
(5) Plugs and receptacles are numbered on the side to which the associated connector is attached. To avoid confusion, some individual pins are identified by letters which appear directly on the connector.
b. Trouble-shooting Steps. The first step in servicing a defective radio set is to section-alize the fault. Sectionalization means tracing the fault to the component or circuit responsible for the abnormal operation of the set. The second step is to localize the fault. Localization means tracing the fault to the defective part responsible for the abnormal condition. Some faults such as burned-out resistors, r-f arcing,
RECEIVER DISABLING
0N I9 O 10N
ry2oo -I U~~~I 7*00
t—. sw2oo sw2oi r—
J_ OFF O O ’ O O OFF
eC-312 BC-342
I\ /k NORMAL
TO RADIO -<------------° A°----------“---* T° RAOI°
RECEIVER SW204 V \> RECEIVER
BC-3l2-(> ° O TRANSPOSED BC-342C)
OUTPUT 20 AUDIO RECEIVER OUTPUT OUTPUT 20 AUDIO
RECEIVER DISABLING
ry °nH l T3°n 200^ J—.J T—-4 c
♦___ SW SW20l ___f
1---1 o o200 normal o o
JL off a o off -i
BC-312 f\-Zl BC-342
TO RADIO -4---------•—O Y O ♦ ----------► TO RADIO
RECEIVER / \ RECEIVER
BC-3I2-C1 SW204 O O TRANSPOSED 8C-342-C )
OUTPUT 2D AUDIO TRANSPOSED OUTPUT 2D AUD10
©RECEIVER OUTPUT
V tl 13801
Figure 105. Diagram of change in receiver disabling circuits.
170. Change in Coupling Coils for
Doublet Antenna Kit
a. A change has been made in the coupling coils for the doublet antenna kits supplied with Radio Sets SCR-399-A and SCR-499-A. However, 85
145
and shorted transformers can be located by sight, smell, and hearing. The majority of faults, however, must be located by checking voltage and resistance.
c. Sectionalization. Careful observation of the performance of the radio set while turning the equipment on often sectionalizes the fault to the transmitter or the receiver, and careful observation of the meters on the transmitter front panel often determines the stage or circuit at fault. Additional sectionalizing of the fault will be discussed in paragraphs 178 and 179.
d. Localization. Paragraphs 178 and 180 through 182 describe the method of localizing faults within the individual components. These paragraphs include trouble-shooting charts which list abnormal symptoms and their probable causes. The charts also give the procedure for determining which of the probable locations of the fault is the exact one. In addition, there are a number of drawings which show the resistance and voltage at every socket pin connection.
172. Voltage Measurements
a. General. Voltage measurements are an almost indispensable aid to the repairman, because most troubles either result from abnormal voltage or produce abnormal voltages. Voltage measurements are taken easily, because they are always made between two points in a circuit and the circuit need not be interrupted.
(1) Unless otherwise specified, the voltages listed on the voltage charts are measured between the indicated points and ground.
(2) Always begin by setting the voltmeter on the highest range so that the voltmeter will not be overloaded. Then, if it is necessary to obtain increased accuracy, set the voltmeter to a lower range.
(3) In checking cathode voltage, remember that a reading can be obtained when the cathode resistor is actually open. The resistance of the meter may act as a cathode resistor. Thus, the cathode voltage may be approximately normal only as long as the voltmeter is connected between cathode and ground. Before the cathode voltage is measured, make a resistance check with a cold circuit to determine whether the cathode resistor is normal.
b. Precautions Against High Voltage. Certain precautions must be followed when
measuring voltages above a few hundred volts. High voltages are dangerous and can be fatal. When it is necessary to measure high voltages, observe the following rules :
(1) Connect the ground lead to the voltmeter.
(2) Place one hand in your pocket. This will eliminate the possibility of making accidental contact with either ground or another part of the circuit and causing the electricity to travel from one hand to the other.
(3) If the voltage is less than 300 volts, connect the test lead to the hot terminal (which may be either positive or negative with respect to ground).
(4) If the voltage is greater than 300 volts, shut off the power, connect to the hot lead, step away from the voltmeter, turn on the power, and note the reading on the voltmeter. Do not touch any part of the voltmeter, particularly when it is necessary to measure the voltage between two points which are above ground.
c. Voltmeter Loading. It is essential that the voltmeter resistance be at least 10 times as large as the resistance of the circuit across which the voltage is measured. If the voltmeter resistance is comparable to the circuit resistance, the voltmeter will indicate a voltage lower than the actual voltage present when the voltmeter is removed from the circuit.
(1) The resistance of the voltmeter or any range can always be calculated by the following simple rule: Resistance of the voltmeter equals the ohms per volt multiplied by the full-scale range in volts. For example: The resistance of a 1,000-ohm-per-volt meter on the 300-volt range is 300,000 ohms (7? = 1,000 ohms per volt times 300 volts = 300,000 ohms).
(2) To minimize the voltmeter loading in high-resistance circuits, use the highest voltmeter range. Although only a small deflection will be obtained (possibly only 5 divisions on a 100-division scale), the accuracy of the voltage measurement will be increased. The decreased loading of the voltmeter will more than compensate for the inaccuracy which results from reading only a small deflection on the scale of the voltmeter.
(3) When a voltmeter is loading a circuit, the effect can always be noted by comparing the voltage reading on two successive ranges. If the voltage readings on the two ranges do not agree, voltmeter loading is excessive. The
146
reading (not the deflection) on the highest range will be greater than that on the lowest range. If the voltmeter is loading the circuit heavily, the deflection of the pointer will remain nearly the same when the voltmeter is shifted from one range to another.
(4) The ohm-per-volt sensitivity of the voltmeter used to obtain the readings recorded on the voltage and resistance charts in this manual is printed on each chart. Use a meter having the same ohm-per-volt sensitivity; otherwise it will be necessary to consider the effect of loading.
173. Resistance Measurements
a. Normal Resistance Values. When a fault develops in a circuit, its effect will often show up as a change in the resistance values. To assist in the localization of such faults, trouble-shooting data includes the normal resistance values as pleasured at the tube sockets and at key terminal points. These values are measured between the indicated points and ground, unless otherwise stated. Often it is desirable to measure the resistance from other points in the circuit to determine whether the particular points in the circuit are normal. The ■normal resistance values at any point can be determined by referring to the resistance values shown in the schematic diagram, or by use of the resistor color code. (See fig. 154.)
b. Precautions. (1) Before making any resistance measurements, turn off the power. An ohmmeter is essentially a low-range voltmeter and battery. If the ohmmeter is connected to a circuit which already has voltages in it, the needle will be knocked off scale and the voltmeter movement may be burned out.
(2) Capacitors must always be discharged before resistance measurements are made. This is very important when checking power supplies that are disconnected from their load. The discharge of the capacitor through the meter will burn out its movement, and in some cases may endanger life.
c. Correct Use of Low and High Ranges. It- is important to know when to use the low-resistance range and when to use the high-resistance range of an ohmmeter. When checking the circuit continuity, the ohmmeter should be set on the lowest range. If a medium or high range is used, the pointer may indicate zero ohms, even if the resistance is as high as 500
ohms. When checking high resistances or measuring the leakage resistance of capacitors or cables, the highest range should be used. If a low range is used, the pointer will indicate infinite ohms, even though the actual resistance is less than a megohm.
d. Parallel Resistance Connections. In a parallel circuit the total resistance is less than the smallest resistance in the circuit. This is important to remember when trouble shooting with the aid of a schematic diagram.
(1) When a resistance is measured and the value is found to be less than expected, make a careful study of the schematic to be certain that there are no resistances in parallel with the one that has been measured. Before replacing a resistor because its resistance measures too low, disconnect one terminal from the circuit and measure its resistance again to make sure that the low reading does not occur because some part of the circuit is in parallel with the resistor.
(2) In some cases it will be impossible to check a resistor because it has a low-voltage transformer winding connected across it. If the resistor must be checked, disconnect one terminal from the circuit before measuring its resistance.
e. Checking Grid Resistance. When grid resistance is checked, a false reading may be obtained if the tube is still warm and the cathode is emitting electrons. Allow the tube to cool, or reverse the ohmmeter test leads so that the negative ohmmeter test lead is applied to the grid.
f. Tolerance Values for Resistance Measurements. Tolerance means the normal difference that is expected between the rated value of the resistor and its actual value.
(1) Most resistors that 'are used in radio circuits have a tolerance of at least 20 percent. For example, the grid resistor of a stage might have a rated value of 1 megohm. If the resistor were measured and found to have a value between 0.8 and 1.2 megohms, it would be considered normal. As a rule, the ordinary resistors used in circuits are not replaced unless their values are off more than 20 percent. However, in some cases precision resistors and potentiometers are used. When a resistor is used whose value must be very close to its rated value, the tolerance is usually stated on the diagram or the maintenance parts list.
(2) The tolerance values for transformer
147
windings are generally between 1 and 5 percent. As a rule, suspect a transformer which shows a resistance deviating more than 5 percent from its rated value. Allow the transformer to cool off before the resistance test is made.
g. High-resistance Measurements. Many leakages will not show up when measured at low voltages. Most ohmmeters use a maximum test voltage of 15 volts on the highest resistance range. Where it is necessary to measure resistance above a few megohms or the leakage resistance between conductors of a cable, the test should be made using an applied voltage of 100 volts or more. If it is possible to ground one end of the resistance being checked, one of the low-voltage power supplies in the equipment can be used to provide about 300 volts for making these high-resistance measurements. The manner in which such measurements are made is indicated in figure 106. This method should be used only when the resistance being measured is very high. Be careful not to handle the meter after the circuit has been completed. The meter used should have an ohm-per-volt sensitivity of 1,000 ohms or more. The resistance of the meter is equal to the ohm-per-volt sensitivity multiplied by the range to which the meter is set. The derivation of the formula Rx = 3002?m is
V
shown below. Rx is the unknown resistance, Rm is the meter resistance, and V is the voltmeter reading.
7^ = 300-7
Rm V
If Rx is very large, V will be small in comparison to 300. Assuming that 300-V can be re-
+ 300 VOLTS
POWER SUPPLY
VOLTMETER
RESISTANCE BEING CHECKED
Rx = ^Rm (APPROX.)
EXAMPLE
V=5 VOLTS. THE METER IS USED ON ITS 300 VOLT RANGE AND HAS A RESISTANCE OF 1,000 OHMS-PER-VOLT.
RM = 300 X 1,000= 300,000 OHMS.
Rx: X 300,000 =18 MEGOHMS.
□
TL3553O
Figure 106. Measurement of high resistance.
placed by 300, the formula Rx — 300 is obtained.
X ~V~
When solved for Rx this gives Rx = 30QRm.
V
When making the measurement, the meter should first be put on the 300-volt scale to protect it in case Rx is very low. If the voltage used is not 300 volts, the correct value should be inserted in the formula in place of 300.
174. Capacitor Tests
Capacitors which are leaky or shorted can be found by resistance checks of the stage. A capacitor which is suspected of being open can best be checked by shunting a good capacitor across it. In i-f (intermediate-frequency) circuits, keep the lead to the capacitor as short as the original capacitor leads. In 1-f (low-frequency) circuits (less than 1 megacycle), the test capacitor leads may be several inches long. A capacitor color code is shown in figures 152 and 153 for checking the capacitor value against the value shown on the circuit diagram.
175. Current Measurements
Current measurements, other than those indicated by panel meters, are not ordinarily required in trouble shooting in the radio set. Under special circumstances, where the voltage and resistance measurements by themselves are not sufficient to localize the trouble, a current measurement can be made by opening the circuit and connecting an ammeter to measure the current. This procedure is not recommended except in very difficult cases.
a. When the meter is inserted in a circuit to measure current, it should always be inserted away from the r-f end of the resistance. For example, when measuring plate current, do not insert the meter next to the plate of a tube, but insert it next to the end of the resistor which connects to the power. This precaution is necessary to keep the meter from upsetting the r-f voltages.
Caution: A meter has least protection against damage when it is used to measure current. Always set the current range to the highest value. Then if necessary, decrease the range to give a more accurate reading. Avoid working close to full-scale reading because this increases the danger of overload.
b. In most cases, the current to be measured flows through a resistance which is either known or can be measured with an ohmmeter.
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The current flowing in the circuit can be determined by dividing the voltage drop across the resistor by its resistance value. The drop across the cathode resistor is a convenient method of determining the cathode current.
176. Tube Checking
Tube checkers are used to check the emission of electrons from the cathode and to test for shorted elements. Tube checkers will not test the performance of high-voltage tubes, rectifiers, or some special tubes in the modulator and rectifier. Tube checkers are useful, however, for checking receiving-type tubes used in the various components.
a. Results obtained from a tube checker are not always conclusive, because the conditions are not the same as those under which the tube operates in the set. For this reason, the final test of a tube must be its replacement with a tube which is known to be good. In many cases it is quicker and more reliable to replace a suspected tube with a good one than to check it with the tube checker.
b. An operating chart and an instruction book or technical manual are provided with the tube checker. This chart indicates the setting of the tube checker for each tube type. The number of controls, their arrangement, and their settings vary with different types of tube checkers.
177. Analyzer BC-1052-E
a. General. Analyzer BC-1052-E is packed in Chest CH-89-A. Directions for setting the analyzer will be found on the chart in the cover of the chest. This equipment can be used for the following purposes:
(1) Voltage measurements, both direct and alternating, from less than 1 to 3,000 volts.
(2) Continuity tests.
(3) Determining values of resistors, 0 to 10 megohms.
(4) D-c measurements from 0.1 ma to 15 amperes.
b. Resistance Measurements. To test any resistor—
(1) Set the analyzer switches and make test prod connections as indicated in the chart for the range into which the resistor falls.
(2) Short the test prods and adjust the meter for full-scale deflection (zero ohms) by use of OHMS ADJUST knob.
(3) Touch the test prods to the ends of the resistor, at least one end of which should be disconnected from the circuit.
(4) Read the ohms on the OHMS scale, and multiply that reading by the value indicated on the ohms range on the rotary selector switch. Note. The ohms adjustment must be made every time the range switch is changed from one range to another.
c. Measurement of Alternating and Direct Voltages.
Caution: Whenever the approximate voltage, current, or db level is unknown, always begin measurements with the highest range to prevent damaging the instrument by an overload.
(1) Refer to the chart for correct settings of controls, switches, jacks, and test prods before making any measurements.
(2) The DECIBEL calibration is for use across 500-ohm lines and loads. The scale is read directly in db.
(3) The OUTPUT jacks are for measuring the voltage or db level of any a-c or audio voltage. Internal circuits are made through a 0.1-mf isolating capacitor inside the instrument, and in such cases alternating current or audio superimposed on a d-c voltage may be read without harm to the analyzer.
d. High-voltage Measurements.
Warning: It is extremely dangerous to make this measurement. Contact with the high voltage in Radio Transmitter BC-610-E may be fatal. Do not make this measurement except as a last resort, and then always arrange to have someone else present. The recommended procedure for measuring the high voltage is as follows :
(1) Insulate the analyzer well above ground by placing it on dry boards or other insulating material at least 1 inch thick.
(2) Set analyzer controls to proper positions for measuring 3,000 volts as indicated on the analyzer chart.
(3) Remove coil unit L7.
(4) Place red (positive) test lead prod into center jack of the jack bar of the coil unit.
(5) Connect black (negative) test lead to any convenient ground on the transmitter frame.
(6) Open right-hand cover door (over tuning units) to open its interlock switch. (This switch will be used to close the circuit (13) below).
(7) Fasten down the interlock switch at the left-hand cover door so that it is closed.
149
(8) See that the back screen is in place so that its interlock is closed.
(9) Arrange the red (positive) test prod and cord so that the cord is extremely well insulated. The cord should be carefully supported so that it is free and clear of the door and frame of the transmitter and any components.
(10) Stand clear of the red (positive) test lead and see that no one comes in contact with it when voltage is on.
(11) Set PLATE POWER switch of the transmitter at ON.
(12) Put your left hand in your pocket.
(13) With your right hand, turn on the high voltage by pressing the interlock switch at the right-hand cover door.
(14) Read the voltage indication on the analyzer and release the interlock switch.
(15) Set PLATE POWER switch to OFF and remove fastening from left-hand cover interlock when finished.
e. Internal Batteries. The self-contained batteries of the analyzer consist of two 714-volt C batteries (Batteries BA-34), one 1^-volt heavy-duty dry cell (Batteries BA-34), and one 11/2-volt heavy-duty dry cell (Battery BA-30). These may be replaced by removing the four screws from the front panel. Remove the batteries by loosening the screws holding the brackets which hold the batteries in place. Be sure to observe the polarity when replacing batteries. The 1^-volt battery is held in place by spring clamps. Be sure to cut out a section of the battery paper cover to permit a good connection to the zinc shell.
178. Trouble-Shooting Procedures
Caution: Do not change fuses or make repairs with the high voltages on, for under this condition a potential of 2,000 to 2,500 d-c volts is present on all three decks of the transmitter.
a. Failure of this equipment to operate properly will usually be caused by one or more of the following faults.
(1) Improperly connected power cable between Power Unit PE-95-( ) and Shelter HO-17-A.
(2) Worn, broken, or disconnected cords or plugs.
(3) Defective fuses.
(4) Burned relay contacts due to overloads.
(5) Wires broken from excessive vibration.
(6) Defective tubes.
(7) Inactive (dirty or cracked) crystal.
b. When failure is encountered and the cause is not immediately apparent, check the above items before starting a detailed examination of the component parts of the system.
c. Check fuses at an early stage in trouble shooting. Do not continue to burn out fuses before looking elsewhere to determine the basic source of the trouble. Insertion of an electric lamp in place of a fuse will often prove helpful in tracing the source of the trouble if fuses continue to burn out.
d. The cause of the trouble can usually be traced to the component at fault by means of the meters and controls on the equipment itself. The use of the schematic diagrams and a logical system of reasoning will almost always isolate the fault. For example: If the transmitter cannot be keyed from either KEY jack or Junction Box JB-70-A, the trouble might be in the 12-volt power supply, relay RY200, switch SW203, the cording from the junction box to the speech amplifier, the cord from the speech amplifier to the transmitter, or the transmitter itself. To isolate the trouble proceed as follows:
(1 ) Switch the BATTERY SOURCE switch on Junction Box JB-70-A to the other 12-volt source.- If this does not clear the trouble, the 12-volt supply is probably not at fault.
(2 ) Plug the key into the KEY jack on the speech amplifier and try to key the set. If the transmitter cannot be keyed, the trouble is in the junction box or the connecting cord. If the transmitter still cannot be keyed, the trouble is in the cord from the speech amplifier to the transmitter or in the transmitter.
(3 ) Throw the EXCITER PLATE POWER switch on the transmitter to ON. If no excitation is indicated on the EXCITATION METER the trouble is in the transmitter.
179. Trouble-Shooting Charfs
The accompanying trouble-shooting charts, if properly used, simplify trouble shooting. There are four charts. The first chart covers the sec-tionalization of trouble in Radio Sets SCR-399-A and SCR-499-A. This chart lists the various symptoms which may be recognized easily by the operator, and gives the probable location for the existing trouble as well as the recommended correction. It tells the operator whether the trouble is in the transmitter, the receivers, the speech amplifier, the junction box, or the power supply. By proper use of this chart, the operator can isolate the trouble to
150
one particular component of the equipment, and thus save time that might otherwise be lost in checking components that are free of trouble. The second chart shows the localization of trouble in Radio Transmitter BC-610-E. This chart will aid in determining which stage in the transmitter is at fault, and will aid in localizing the trouble to the individual part in the circuit which is causing the abnormal condition.
The third and fourth charts are similar to the second, except that they deal with localizing the trouble in Speech Amplifier BC-614-E and Junction Box JB-70-A respectively. Therefore, the first chart will be used mainly by the operator, whereas the last three, covering trouble shooting within the various components, will be used by the repairman.
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180. Sec+ionalizing Trouble in Radio Sets SCR-399-A and SCR-499-A
Symptoms Probable trouble Corrections
1. Power Unit PE-95-( ) fails to start when START button is pressed 2. Power unit starts, but no power is available at Radio Set SCR-399-A or SCR-499-A 3. No filament power when FILAMENT POWER switch is set to ON 4. Low or zero reading on ANTENNA CURRENT meter 5. No grid excitation indicated when EXCITATION METER switch is set to P.A. GRID position (assuming intermediate amplifier is operating properly) 6. No plate current indicated on P.A. PLATE meter. Necessary grid current present. HIGH VOLTAGE PROTECT switch set to HIGH VOLTAGE PROTECT 7. Excessive plate current indicated on P.A. PLATE meter 8. PLATE POWER switch thrown to OFF. P.A. PLATE meter indicates plate current still flowing 9. No excitation indicated by EXCITATION METER when EXCITER PLATE POWER switch is set to ON position 10. Transmitter functioning normally. Radio Receivers BG-312-( ) and BC-342-( ) fail to disable during transmission 1. Discharged battery in power unit might operate start relay, but fails to turn over the engine Broken wire in power cord or bad connection at plug START and STOP leads interchanged or disconnected either at Junction Box JB-70-A or at trailer terminal board 2. Loose socket connection. Circuit breaker defective or circuit breaker nob closed 3. Fuse FSi, FS2, or FS4 open. FILAMENT POWER switch, defective Damaged Cord CD-763 or poor plug connections Filament resistor Ris defective 4. Incorrect control setting on Antenna Tuning Unit BC-939-A. Sections of transmitting antenna missing Insufficient antenna coupling 5. Tube V1 e defective or, improperly inserted Open r-f choke CIIg2 Adjustable resistor Ru defective 6. TRANS. ON-OFF switch on Junction Box JB-70-A not thrown to TRANS. ON position Reset necessary on overload relay Open fuse FS3 Interlock switches not closed Short in high-voltage circuit continually tripping overload relay Rectifier tube Ve or V7 defective Missing or improperly installed coil unit on jack bar Resistor R19 defective, or loose in socket 7. Improper tuning of tank circuit Wrong coil unit Failure to use vacuum capacitor C28 when operating below 2.5 me Excessive antenna coupling No bias voltage due to open fuse FS5 or tube V 5 defective 8. Contacts on relay RY 1 sticking because of severe overload 9. Tuning unit improperly seated in socket Tube V8 or V9 defective EXCITER PLATE POWER switch defective BAND SWITCH not set to proper channel r 10. RECEIVER DISABLING switches not turned to ON position Junction Box JB-70-A not functioning properly 1. Start power unit with hand crank See TM 11-904 Repair cord or connection Connect leads properly 2. Tighten connection. Replace or close circuit breaker 3. Replace open fuse. Replace switch Repair cor<| or connection 4. Set control according to tuning chart Replace missing sections Increase antenna coupling 5. Replace tube or insert tube properly 6. Throw switch to ON Press OVERLOAD RESET switch Replace fuse Close panels on top of transmitter tightly Check high-voltage circuit Replace defective tube Install coil unit properly Replace resistor R19, or tighten 7. Tune tank circuit according to tuning chart Use proper coil unit Install capacitor C28 Reduce coupling Replace fuse FS5 or tube V5 8. Clean contacts of relay RYi Caution: Leave plug out of socket SOo when working on this relay 9. Insert tuning unit firmly in socket Replace tube Set switch to proper channel 10. Turn switch to ON position See paragraph 182.
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181. Localizing Trouble in Radio Transmitter BC-6I0-E
Symptoms Probable trouble Corrections
1. FILAMENT POWER switch thrown to ON position. Green lamp does not light. FIL. VOLTAGE meter indicates filament voltage 2. FILAMENT POWER switch thrown to ON position. Green lamp does not light. No voltage indicated by FIL. VOLTAGE meter 3. FILAMENT POWER switch at ON position. Green lamp lights. No voltage indicated on FIL. VOLTAGE meter 4. FILAMENT POWER switch at ON position. Green lamp lights. FIL. VOLTAGE meter indicated filament power present. Tubes Vi, V2, and V5 not lighted 5. EXCITER PLATE POWER switch at ON position. No intermediateamplifier grid current indicated when EXCITATION METER SWITCH is at INT. AMP. GRID position. Tuning unit set according to tuning chart. M.O.-XTAL switch and BAND SWITCH at proper positions 1. Lamp LM3 burned out 2. Fuse FSi, FS2 or FS4 burned out FILAMENT POWER switch defective Damaged power Cord CD-763, or poor contacts at sockets SO201 or SO6 3. Tube V13, V14, or V15 not in sockets Filament resistor Ris defective 4. Fuse FS5 open 5. Switch SW3 defective . Tube Vs or V9 defective Defective rectifier tube V12 Open resistor Rs or choke CH7 1. Replace lamp 2. Replace fuse Replace switch Repair cord or sockets 3. Place tubes in sockets Replace resistor Ris 4. Replace fuse FS5 5. Replace switch Replace defective tube Replace defective tube Replace defective part
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182. Localizing Trouble in Junction Box JB-70-A
Symptoms
1. TRANS. ON-OFF switch at the TRANS. OFF position during c-w operation. No plate current indicated on P.A. PLATE meter when transmitter is keyed
2. Press-to-talk switch is depressed during phone operation. No plate current indicated on P.A. PLATE meter
3. Transmitter functioning normally on both c-w and phone operation. Radio Receivers BC-312-( ) and BC-342-( ) fail to disable during transmissions
4. Transmitter operating normally. Sidetone is not being received at Radio Receivers BC-312-( ) and BC-342-( )
5. Transmitter cannot be keyed during c-w operation from a remote position
6. Transmitter cannot be modulated from a remote position
7. During remote operation the telephone is not being fed reception from Radio Receiver BC-312-( ) or BC-342-( )
Probable trouble
1. Contacts of switch SW203 closing circuit of relay RYi fail to close
Relay RY200 fails to function
Wiring from SW203 to PL200 defective
Contacts of relay RY200 in circuit of the cathode of oscillator tube Vs fail to close
2. Relay RY200 fails to function Press-to-talk switch defective
12-volt power supply for energizing relay RY200 lacking
Contacts of relay RY200 in the circuit of relay RYi fail to operate
3. RECEIVER DISABLING switch SW200 or SW201 not turned to ON position
Switches SW200 and SW201 defective
4. C.W.-SIDETONE switch SW205 at OFF position
Relay contacts of RY200 in circuit of switch SW205B fail to close
5. REMOTE CONTROL EE-8 switch SW202 at incorrect position. (Also see 1 above)
6. Capacitor C202 defective. TRANS. ON-OFF switch SW203 at incorrect position
7. TRANS. ON-OFF switch SW203 at an incorrect position
REMOTE CONTROL EE-8 switch SW 202 at incorrect position
Corrections
1. Repair, adjust, and clean contacts
12-volt power supply lacking
Repair relay RY200
Repair wiring
Repair, clean, or adjust contacts
2. Repair or replace relay RY200
Repair or replace switch, or replace microphone
Repair 12-volt power supply from
Power Unit PE-95-( )
Switch to auxiliary battery supply
Repair, clean, or adjust contacts of relay RY200
3. Turn switch to ON position
Repair or replace switches SW200 and SW201
4. Turn C.W.-SIDETONE switch to TO BC-312 or to TO BC-342 position
Clean, adjust, or repair contacts of relay RY200
5. Place switch SW202 at correct position
6. Replace defective capacitor C202 Place TRANS. ON-OFF switch at TRANS. ON position
7. Place TRANS. ON-OFF switch at REC. TO EE-8 position
Turn REMOTE CONTROL EE-8 switch to correct position
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183. Localizing Trouble in Speech Amplifier BC-6I4-E
Symptoms Probable trouble Corrections
1. FILAMENT POWER switch on transmitter power panel closed. Red lamp fails to light 2. FILAMENT POWER switch at ON position, filament voltage present at all tubes, plate voltage lacking 3. Transmitter can be modulated by a dynamic microphone or Telephone EE-8-( ), but not by a carbon microphone 4. Transmitter can be modulated by a carbon microphone, but not by a dynamic microphone or Telephone EE-8-( ) 5. Transmitter can be modulated by carbon or dynamic microphone, but not by Telephone EE-8-( ) 6. Filament voltage and plate power supplied to all tubes. Transmitter can be modulated. Sidetone lacking during c-w operation 7. Filament voltage and plate power supplied to all tubes. Transmitter can be modulated. Speech limiter fails to limit speech peaks. 1. Fuse FSs open, lamp LMioi burned out 2. Rectifier tube V107 defective Secondary 250-volt winding of transformer T103 burned out Shorted filter capacitor Cios or C109 Open filter choke CH 101 3. Resistor Rno or R123 defective Transformer T101 defective Shorted capacitor C120 or Cno 4. Tube V101 defective Resistor R102 or R103 defective 5. Resistor Rios defective 6. Oscillator tube Vine defective Resistor R139, R140, Rise, R138, or R137 defective Amplifier tube Vios defective Resistor R122 or R141 defective • Capacitor C117 or Cm defective 7. LIMITER CONTROL R134 defective Speech limiter tube V105 defective Transformer T104 defective Capacitor Cue defective Capacitor Cm defective Resistor R109 defective 1. Replace fuse FS5, replace lamp LM101 2. Replace tube V107 Replace transformer T103 Replace shorted capacitor Replace defective choke 3. Replace defective resistor Replace transformer Replace capacitor 4. Replace defective tube Replace defective resistor 5. Replace defective resistor 6. Replace defective tube Replace defective resistor Replace defective tube Replace defective resistor Replace defective capacitor 7. Replace resistor Replace tube Replace transformer Replace capacitor Replace capacitor Replace resistor
Section VIII. REPAIRS
184. Replacement of Parts
Careless replacement of parts often make new faults inevitable. Note the following points:
a. Before a part is unsoldered, note the position of the leads. If the part (such as a transformer) has a number of connections to it, tag each of the leads.
b. Be careful not to damage other leads by pulling or pushing them out of the way.
c. Do not allow drops of solder to fall into the set, since they may cause short circuits.
d. A carelessly soldered connection may create a new fault. Be very careful to make well-soldered joints, since a poorly soldered joint is one of the most difficult faults to find.
e. When a part is replaced in r-f or i-f circuits, place it exactly as the original one was placed. A part which has the same electrical value but different physical size may cause trouble in h-f (high-frequency) circuits. Give
particular attention to proper grounding when replacing a part. Use the same ground point as in the original wiring. Failure to observe these precautions may result in decreased gain, or in oscillation of the circuit.
185. Replacement of Tubes
a. Tube V16 is removed as follows:
(1) Open the doors in the top of the transmitter over the plate coil and the tuning units.
(2) Take out the tuning units and remove tubes V8 and Vo from their sockets.
(3) Remove the grid lead from the grid cap on the side of tube V16 and the plate lead from the plate cap on top.
(4) Turn the tube counterclockwise until it can be lifted out of its socket.
(5) Remove the tube through the door over the tuning unit side of the transmitter.
155
b. Modulator tubes V3 and V4 are removed as follows:
(1) Remove the back screen.
(2) Take off the plate and grid leads from the caps.
(3) Turn the tube counterclockwise and lift it out of the socket.
c. High-voltage rectifier tubes V6 and V7 are removed as follows:
(1) Remove the back screen.
(2) Disconnect the plate lead from the cap.
(3) Turn the tube counterclockwise and lift it out of the socket.
d. To remove tubes V10, Vu, and V12, proceed as follows:
(1) Lift up the two doors in the top cover.
(2) Remove the tuning units.
(3) Loosen the clamp around the base of the tube with a screwdriver by reaching in through the door over the plate coil.
(4) Pull the tube straight up, gently rocking it from side to side.
186. Removal of Antenna Tuning Unit BC-939-A
To remove the antenna tuning unit proceed as follows:
a. Disconnect the antenna and ground leads.
b. Disconnect the coaxial cable leading from the transmitter.
c. Take off the four wingnuts holding the tuning unit to the top of the transmitter.
d. Lift the unit up and forward.
187. Removal of Top of Transmitter Cabinet The top of the transmitter cabinet should be taken off when extensive work is to be done in the r-f section. Remove the antenna tuning unit first (par. 186) ; then proceed as follows:
a. Remove the eight bolts holding the top to the mounting straps.
b. Unscrew the four wing-head screws which secure the top to the cabinet.
c. Disconnect the two leads which are plugged in terminal strip TSg on the exciter deck.
d. Lift the cover clear from the cabinet.
188. Removal of R-F Section
The r-f section may be removed from the transmitter as follows:
a. Remove all tubes for safekeeping.
b. Disconnect the leads from terminals 1 and 3 on terminal strip TSX on the exciter chassis apron.
c. Disconnect the two leads to the coil of re
lay RY4, and release thqm from the clamp on the side of the cabinet.
d. Disconnect the leads to meter M2, and clear them from the bracket under the meter.
e. Disconnect the black lead to capacitor C12.
f. Pull out plugs PLX and PL2 from their sockets on the modulator deck, and release the laced cable from its bracket on the modulator chassis.
g. Remove the eight bolts which hold the r-f section to the straps of the cradle.
h. Remove the 14 bolts which fasten the r-f section to the modulator section.
i. Lift the r-f section off.
189. Removal of Chests From Shelter
Whenever it is necessary to remove any of the major components of Radio Set SCR-399-A from Shelter H0-17-A, move the truck in such a position as to jack-knife Trailer K-52-( ), so that the rear of the truck will become more readily accessible. If possible, disconnect the trailer.
a. Removal of Chest CH-89-A (Seat Bench) . Two men are required to remove Chest CH-89-A from the shelter.
(1) Unscrew the six wing-head bolts holding the chest to the floor.
(2) Lower the chest from the floor of the truck to the ground, holding it by its handles.
b. Removal of Chest CH-88-A (Wall). Two men are required to remove Chest CH-88-A from the shelter.
(1) Remove cotter pins from trunk clamps.
(2) Unclasp all four trunk clamps.
(3) Remove chest by its handles.
c. Removal of Chest CH-119-A. Two men are required to remove Chest CH-119-A from the shelter.
(1) Remove Chests GH-88-A and CH-89-A.
(2) Remove Tool Equipment TE-48 and Cord CD-652 from Chest CH-119-A to lighten weight.
(3) Unclasp the four trunk clamps.
(4) Slide chest to the door and lower to ground.
d. Removal of Chest CH-120-E. Four men are required to remove Chest CH-120-E from the shelter.
(1) Disconnect all cords connecting Chest CH-121-A to Chest CH-120-A and close the cover of the latter.
(2) Disconnect Cord CD-659 from Chest CH-109-A.
156
(3) Disconnect all cords from the bottom of Junction Box JB-70-A.
(4) Disconnect ground straps from bottom of chest.
(5) Disconnect Cord CD-764 from front of Speech Amplifier BC-614-E, and remove cord.
(6) Loosen turnbuckles holding Chest CH-120-A to table frame after removing safety wires.
(7) Remove chest from table frame and lower to ground.
190. Removal of Radio Transmitter BC-610—E Four men are required to remove Radio Transmitter BC-610-E from the shelter.
a. Remove Chest CH-89-A as described in paragraph 189.
b. Disconnect Cords CD-763 and CD-764 from their sockets on the rear of the transmitter.
c. Remove Antenna Tuning Unit BC-939-A from the top of the transmitter as described in paragraph 186.
d. Unscrew the four long wrench nuts holding the cradle of the transmitter to the floor of the shelter.
e. Move the transmitter and its cradle directly toward the right wall to the center of uhe shelter.
f. Move the transmitter around into the center aisle and toward the rear of the truck, (it will now be necessary to have three of the men on the ground to assist in lowering the transmitter from the floor of the shelter to the ground.)
g. Lower the transmitter directly to the ground by the four handles.
191. Replacement of Switches in Radio Transmitter BC-6I0-E
a. General. The method of removal and replacement of the majority of the switches in the transmitter is apparent upon inspection. It is important, however, that all leads to the switch be tagged before they are disconnected from the lugs or terminals.
b. Removal of Band Switch SW8. First remove the r-f section as described in paragraph 188. Rest the r-f section on its top, and remove bank switch SW8 as follows:
(1) Disconnect all leads to the switch; tag each one.
(2) Remove the knob from the shaft by loosening the two setscrews.
(3) Remove the nut and washer from the shaft on the front of the panel.
(4) Remove the switch from the bottom of the exciter deck by unscrewing the five nuts which secure it to the deck.
(5) Replace in reverse order. When replacing the knob, see that the setscrew in the side of the handle engages the flat side of the shaft.
192. Replacement of Parts in Speech Amplifier BC-6I4-E
The parts of Speech Amplifier BC-614-E are easily accessible when the chassis is removed from the cabinet. To remove the chassis, disconnect the three cords from the front panel. Release the four winged panel locks and pull the chassis straight out of the cabinet.
a. Limiter Control R134. To replace the limiter control, first loosen the resistor mounting strip just behind the control by unscrewing the two nuts holding the strip to its mounting. Move the strip to the rear. Unsolder the three leads to the control, and tag each. Unscrew the two nuts holding the control to the front of the chassis, and remove the control. Replace in reverse order.
b. Microphone Gain Controls. To replace either microphone gain control, first disconnect the leads to the control. Remove the knob by loosening the setscrew holding it on the shaft. Remove the nut and washer securing the control to the panel, and take the control off the panel. Replace in reverse order.
193. Removal of Junction Box JB-70-A
To remove Junction Box JB-70-A from the cabinet, first disconnect all cords from the right side, front panel, and bottom of the chassis. Disconnect the grounding braid from the bottom of the chassis with a screw driver. Disconnect the remote telephone line,. if connected. Disconnect the cord which connects the junction box to the speech amplifier from its socket on the panel of the speech amplifier. Release the four panel locks and pull the chassis forward. With a screw driver, disconnect the leads from terminal 9, 10, 11, and 12 on TS200 ; and pull the cord through the rubber grommet in the right side of the junction box. Pull the chassis all the way out of the cabinet.
194. Rustproofing and Repainting
When the finish on the cabinets or panels of any of the components of Radio Set SCR-399-A or
157
SCR-499-A has been badly scarred or damaged, rust and corrosion can be prevented by touching rp bared surfacC .< •:|
iH^—\-~xtr’ •/ • r
r-foutputW1< \ <■ 5Sffl\F' i^T , J I i
terminals! <|»B K t (< J C '
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\\ IIMHHME&. w.-'.'. BS fL socket
■ aar-“~r ?T .,.,« ■ ,7 =awr _ur.
\ IfflU JIS * y f
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11______/ A X U. >t4 ■ k:M~
OUTPUT COIL/7 -^— :........ \ z.s’,. Y / '
v AND ^TUNING UNIT CHANNEL
|jL VACUUM CAPACITOR /^"vgTUBE SOCKET / BAND 2 TUNING UNIT CHANNEL
& C28M0UNTING / /
Ly.' ~ CLAMPS ViqTUBE SOCKET BAND I TUNING UNIT CHANNEL itF^Yot
Figure 107. Radio Transmitter BC-610-E—top view of r-f deck.
160
TRANSFORMER CHOKE V^TUBE NEUTRALIZING R-F PLATE FILTER ''Z||
T4 L| SOCKET CAPACITOR C|8 CAPACITOR Cn
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SAND SWITCH / wE3fr | 8AR . J
SWh R-F CHOKE RESISTOR
CH4 Rg
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, ._.... ^^ILI59O2|
Figure 108. Radio Transmitter BC-610-E—bottom view of r-f deck.
161
TRANSFORMER TRANSFORMER SOCKET SOCKET TRANSFORMER CHOKE SOCKET SO^ SOCKET S04 CAPACITOR t5 T3 SO, SO? T9 L2 / £2O_
. \ J /_ >.....................\ J /S capacitorI
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INTERLOCK ELEMENT R,o V5TUBE V4TUBE VgTUBE TRANSFORMER VgTUBE TERMINAL S05 SWITCH SW5 Ba$E SOCKET SOCKET SOCKET T8 SOCKET STR}P TS4 rQ j
Figure 109. Radio Transmitter BC-610-E—top view of modulator deck.
162
TT'" .
' CAPACITOR CAPACITOR. SOCKET SOCKET CHOKE Lg TRANSFORMER SOCKET SOCKET TRANSFORMER Cgj Cgo SO3 / ^3 SOj Tg
SRoft- 51’ » ■ Mr I ww? |i
choke l3|; MQIMOK A -'W^
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SOCKET '"vJUBe” TERMINAL- V2 TUBE V^TUBE V4TUBE V5TUBE HEATER SOCKET INTERLOCK
SO5 SOCKET STRIP TS4 SOCKET SOCKET SOCKET SOCKET ELEMENT Rig SO6 SWITCH
BASE SW5
________________ ___________ _ TLI59O4
Figure 110. Radio Transmitter BC-610-E—bottom view of modulator deck.
163
TRANSFORMER CAPACITOR CAPACITOR CHOKE TERMINAL STRIP TS3 RESISTOR
Ts C|g C23 L4 Rj3
| \ I I \ I \« « •/
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TRANSFORMER V6 TUBE V?TUBE RELAY RELAY RY2
t2 SOCKET SOCKET RY5
-
____1.._______ .. ... .:_______
Figure 111. Radio Transmitter BC-610-E—top view of power-supply deck.
164
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receiver- w Ft .J»4 ii?SKEl^^EEK?t3M
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switch FfiF P^MKSLx^r^
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e^o^Y I 8»Fl ^.TRANSPOSE
source rsS:■ WFW ,■ ■■• «. ■■ »—>•. afJML^ switch sw-,04
switch '|J ’ -\>; L 7' Wfci Wat X -;. ^jBr _
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/ RECEIVER a START- CIRCUIT SIDETONE
REMOTE REMOTE DISABLING TRANSMITTER STOP BREAKER SWITCH
s TELEPHONE CONTROL SWITCH CONTROL SWITCH CB2OO SW2Q5
^TERMINALS SWITCHSW202 SW2oi SWITCH SW203 SW2Q6 ...............................'._______i__________ JLI59I3]
Figure 114. Junction Box JB-70-A—top interior view of chassis.
167
- — — " himuhwi ■ ■" 11 .. —11 --------------------
1
POWER INPUT
i -
XJ LAMP IN CH-121 LAMP (ROOF)
. Bl SI ■ -. fSSr ,
TO SPARE TO BLOWER tHh|K
/ • gn m < %
S0Q^ 620 620 »
I S0205 “
• • \ SOgO7 / TO BC-6IO-( ) HEATER
SO2O1 ■—
w ;* wlP WSz
BATTERY
S0206 CORO CO-565 TO BC-312
• • RECTIFIER
’• RA-63-( )
* w B * I HS S |gj^|jy
AUDIO BC-312 • ^830^
• 9 • 2io S0204 so2 BATTERY SOURCE
SWITCH SW207
.................1 K" .................... WUL..............H Ww / uH?
x r ■ / i
RECEIVER OUTPUT C.W. SIDETONE START \ / rfmoTE
i TRANSPOSE SWITCH SW204 • SWITCH SW2Q5 STOP TRANSMITTER REMOTE TP1 cojnyf
SWITCH SW206 CONTROL CONTROLEE~8 terminals ।
SWITCH SW203 SWITCH SW202
..... 4.:.... ......iA.,..,....,.^ =.:...v . . -c..^ : .- •,: .. __LhAiZlil
Figure 115. Junction Box JB-70—A—bottom view of chassis.
168
C|°8 C|11 C)04 C|07 Guo C120 SOjoi «I23
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/ I v SIDE TONE VOLUME
Il°i CONTROL R|37 . ,,,.„
Figure 116. Speech Amplifier BC—GlJk—E—top interior view of chassis.
169
SOCKET
DYNAMIC MIC.2 SOCKET LAMP LIMITER KEY SOIO2 CAPACITORS ;
CONTROL Rm S0|03 LM|0| CONTROL JACK CAPACITORS / CIO8, <309
।
ex-—x ~ JSr '*■*» \ \ __? I Mj / 7'
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CAPACITOR 1 CAPACITOR
c"s 8GL£52$^»- 1 - c124
y|jyar*fLPaj—*11** '* '*”- ■
CAPACITORS" x 1' K.
ch2,C"3 i^yM. CW «*e* -^ n rYJi
? * >Ss*sxj^z' • •’ •■.—'■■•"•■'■ Jr TRANSFORMER:
VW2TU8E'' Jfcj,-W?Z$~5| ^a»». sJF T|04
socket t———
k •• 'I fa ......0HOKE
socket j^gZ / . -i T.. -Jzfclr ._^- ^J|
~^'••''''-~P jRUI'wJOkLjL' '
1. “ • Wiitwmwfar .
/ / / \ • \ X -
-rr- A .< -r-'A'-im- -, ' ' ' V1A4TUBE
TRANSFORMER V|06TU8E TRANSFORMER SIDE TONE. . . • , V105T.AB fcV tai . Z) antenna
^J|> __•■•-**^37 ]j terminal
BBBIBw ) iV--....~ \
|B9HM M ---------—. •
_Xww* /IHf 1 11
h> Wy toE^SB'- cf It' - TjMal
B I* iiV hA IS^' I i1 i’*i--w'
B&- iSKM L-X
>L^^|Ka]R t ijno ; — ■ !<♦■■/
X ' ■ v—Je I a i jxistez
ANTENNA CURRENT H-F LOADING COIL L44 VACUUM CAPACITOR
h METER M4 C22
CRANK HANDLE FOR
ADJUSTING COIL L44
--------- ... ______________________________ TLI59O9
Figure 118. Antenna Tuning Unit BC—939—A—top interior view of chassis.^
171
IK H-F
LOADING COIL
L44 \ ' VACUUM CAPACITOR
i’ -JB \ ■- \ L-F
. A \Jq \ LOADING COIL
t»W3l Wl ' ' ? L6
,W to ,1 w irrMF- --/ antenna
| 1 ^wwy.±.?o . I gy »__________ / / TERMINAL
HkwF I x • / I
I ^rifTWr^' Z ?■ /• .
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WNIE^^^ — ANTENNA
Si La *81 1»L - SWITCH
;■! 1 3DT M
| ' 1 oo^/ " n —N/VAAz— Q C |O4 — 20M ------------A cmcTAMC 4 Plate
6-plate LIMITER L-. n SDZNE REufly
relay I 1 SIDETONE R|4os s ri39 OSC 6 mod
7.ac VT-233 r!30s Scii5 l AMP 5m^5m vT-231 meter
8GN0 c,,4 0i50M$ I8 VT-94 LI________ V 401 6 audio
|[ _f 7 ,. I ____ 7-AuOlO
NOTE I L—1 Jkv 105 ] 1 _3 VIO8 JZT 1C1|7 e-CNO Jc°-
•s?s£w rZ) ZUhTP”06
microfarads 104 3 ITT P\A/ I VAX r,,„< \j\N ,._II__
unless 3 750 A Co 3 TT 1--♦ 8 TT J38 S a TT 6 "
OTHERWISE 2? 4 ’ * 1 H 100M| H 6 k 8 Sil
INDICATED 35 | L_®_J ’8 i 7 2 ] 78 > L3 5 °3 ChiOi
» k 5 J RI372 < 250 m C,08Cll?9H
’’ SrI3i--------------------►< ] ----,--1|-J-—-
c,,6 ■= >im ioo m> —r—’ | "a
ZZ—ZZ Or.22 1 i Toy s-a rect
H'32 T331 |2M • _, ’TOP.N2 " VT’80
u,o, f 1 c 128 -T | R . 36 OfV'02&V.08 V|07
"—------------------------------— ------1 • 002 t 2Z^'
T - 1 25An--LZ-I A '
4- TUBE SOCKET CONNECTIONS ’ 8?v ,1-1 \l
----------------------- lmioi rV* )n4
nrsZZs VT-94 |-----
4 VT-103 _ ______
(2\ XT) VT-231 I 2 A |6 3 V 250 v I 2 &0v Sv 2A
ms) VT-233 i WWW u)
BOTTOM VIEW OF SOCKETS ' T 103
-------------------- 11 5 V )6 | oO • 60 CyClE
CAPACITORS
REF SYMBOL WORKING VOLTS REF SYMBOL WORKING VOLTS
cIOi CIO2 CIO3 C|04 CIO5 Cl06 ClOT C|08 C|09 Clio Cl n C|,2 Cl 13 C| 14 C| 15 600 V DC 600 V DC 600 V DC 25 V DC 600 V DC 600 V DC 25 V DC 475 V DC 475 V DC 25 V DC 475 V DC 475 V DC 475 V DC 600 V DC 475 V DC C| 16 C| 17 C| IB C119 C|20 C|2l CI22 C|23 C,24 CI25 C|26 C|27 C|28 CI29 C, 30 400 V DC 600 V DC 600 V DC 600 V DC 25 V DC 600 V DC 600 V DC 600 V DC 400 V DC 600 V DC 600 V DC 500 V DC 600 V DC 500 V DC 500 V DC
RESISTORS
REF SYMBOL WATTS REF SYMBOL WATTS
RIOI 1/2 ri2 1 l
rI02 1/2 rI22 1/2
rI03 1/2 R124
rI04 1/2 rI25 2
rI05 1/2 Rl 26 2
RlO6 1/2 R|27 1
rI07 1/2 Rl 26 l
rI08 1/2 rI29 1/2 •
ri09 1/2 ri30 1/2
ri 10 1/2 Rl 31 1/2
Rl 1 2 1/2 rI32 1/2
Rl 1 3 i/Z rI33 1/2
R| 14 V2 rI35 1/2
R| 15 1 rI36 1/2
Rl 16 1/2 rI38 1/2
Rl 17 1/2 Rl 39 1/2
Rl 18 1/2 rI40 1/2
R| 19 1/2 rI4 1 1/2
rI20 1/2 R|42 1/2
TL-848IA
Figure 123. Speech Amplifier BC-614-E—schematic diagram.
MO ___
i-»-----------------------------------B pAv
_£—X ' । °XTAL ||— _ ™
fl " i #5 rA^r/C
1——41—U ~ ______L-j—5 f i
Ln A lir7...................................... W hi L *A-----
\ te'W" - -’JS^ —- SW9.2 C22 L44 M4 ---
_________________________— ——-—----------------------------------■■ ' -------------- --------------------------------------------------------------------------. S»|t । \ “p 3*11.2 — SW||3 ft SW11.4 swil 5 ANTENNA
* - 1- — - - —— - -*- - - - —----X___________ LX CURRENT Z" ------------
„I2VOC — VT-103 VT-94; VT-231 VT-231 VT-95 VT'2.9 L, BAND SWITCH j V _L_
" ' I-_- ' S020l SO2O2 Ciop I
+ I2VDC GND __ _____ KEY VIU& . ———————————_______ I ' e»
. . —। ^p-ftTO BC-6IO-( I /p-^TO HEATER —I—n I_I—It I-[z------- fs- ------------------------------------------------------------------------------- -----—I________ _____________ Rr
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T.v.;r sc“” _------------,,--- 41"“ 1 ? L-—- 1-----F=ff? 'si r v U_______Of:—i'~l t”°“" I r°“ OL
U ---------------.... !--- ip T - _ . — --- ---------------inbnRY3 _/ £_J TT /L"\ 500 f Rs i I
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R 4.---------------------------! _L Ssom • ’ S ___»T-'«5 Esh —1 PLATE '-snS §850 40“> 4 l3-5n.. 3- J- H tl _ 4 POWER STl 43S--- < > r 3 90<1
®»OS ON ON I ■kmflJ’TlOl - r,24 C|09 ~ <~S + Z\7v F 1 I- ST 435 -±- S _£c„ » -fT l0'5A___
n------------------|, , ------,r-. ■—-. I. - —O-xt1.#. h. p Lkff— T _^. ffOEEn ----------------------1------=|—.---------1.
fi#r Mln__J7T3Rl42 ----f- 30 i 3'j°x |L-o- • |-f I ---------------- —
I_ ~ . S *-1 I2sT >200n r J R J __2_ - C|08 5| 700A _ _____ \sw5 -OT I ffl I I I 13 C100 "O
—--------------------|S°arlL . IEz^T ■005 l4 I—ffvT 5m | 5M°| HnH yt-8o| 54 ^(-800—----------------T--------------- tiT-----vt"45\ MOAj C I——| |
lq4 ------1— ------- —==------------------------------------------------------------------zz7.z.;t——1 |--------—.^(7 :r.rM | _4=z?i
6 t ----------------------------------------tp-0 TO LS-3 IN CH-120 125 v kff OVERLOAD SW_____S 2 . S giffO/ ~ --*-----* 02 /
^”2020 4 pfcct 2 ST c ° VT"46A o G 11,1 —" u—— ■ nil-.
.......—■ --s 204 I I KEV Pt-202 FS c725v FS ° 0----------25V _ 4^—| |2,000 NOTE: 1 key SI00A I CO—o TO SC-342-1 > PHONE-2 NO AUDIO Z~X • _2 T ff3 -T t-jM^ =^-1 X I v ALL VALUES ARE IN OHMS OR MF UNLESS
■ffn S ffzn Kn pzn a-vfl -4 A --- . -------------------------------------J PHONE R I " ~" 7\ |\ OTHERWISE INDICATED.
X#4 rP7> I J?o3 IJ 2o 4 IJ205 I J20l __ kffso6 2sa 20a I Loooo— 13 > CffkCp9_ l|lH (/ IT CAP RESISTANCE VALUES SHOWN ON TAPPED
[J200_Y'.01_ 202_______________[ 203_| 204_I 205_____j 20 TO EE - 8 IN CH-120 ftC '2S» 125 V --.J , 75 M S 3 T- 3-7- 6en fLV^ 1/ TRANSFORMERS APPLY TO ENTIRE WINDING
__ HEADSETS BC-312----------------------HEADSETS SC-342-I | SW2 L_ AU0HMLAMENT *INDIN6S ARE LESS THAN TLI44»>
~__ ------------------------- I - ■ C Wff *
L. ... L" ----
Figure 120. Radio Sets SCR—399—A and SCR—499—A—simplified schematic diagram.
CAPACITORS
REF. SYMBOL WORKING VOLTS REF. SYMBOL WORKING VOLTS
Cl 600 V DC C 1 5 2,500 V DC
C2 600 V DC C 1 6 1,000 V DC
C3 600 V DC C 17 1,000 V DC
c4 600 V DC C 1 9 4,000 V DC
^5 600 V DC C20 600 V DC
C6 600 V DC c21 600 V DC
600 V DC C23 600 V DC
C8 500 V DC C21j 1,000 V DC
C9 600 V DC C25 600 V DC
c 10 600 V DC ^26 600 V DC
C | | 6000 V DC - c27 100 V DC
CI3 500 V DC C28 20, 000 V RMS TEST
CI1 2500 V DC C29 5, 000 V DC
RESISTORS
REF. SYMBOL WATTS REF. SYMBOL MATTS
Rl 1/2 RI5 1/2
r2 20 RI6 2
R3 20 RI7 2
R4 1 RI8 75
R5 20 R 19 600
R6 2 R20 10
R7 2 R2I 1/2
R8 2 R22 1/2
R9 20 R23 1
RIO 20 R24 10
R 1 1 100 R25 2
R 12 50 R28 1/2
R 1 3 200 R34 10
Rm 1/2 R35 1/2
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—W GJ feO k* 1 1 (> I ,, note: SW n , o „ ARE GANG- ED . ______ _______________________
tuning f----------6. X -L note; । —« qJ c _ 91 & 92 11, I topcap . 2
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UNIT. 1. T —— ---M SCHEMATIC I I 92 Q) CX—II—X) * 0 00 f-' I T Z^lX. 3 T I X- I
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’-------------------------- L GN0 '— J 3 K ' 4 20M$ 9 £ 14 r (OOM> oj ,
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Vl IU' . ., MMP T VT-IOO • ? /_______,________I 1 , DIAC orrT o 2.KCY । | I
3 7, 3-cap!----------------- I note: ! 20 1.. vtAiarRECT‘ R It 3. ACCOM I I |
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5/ Xt MMP -—A-n 9 3f An 4-002 | IN OHMS OR MFD ( Cj, 311 , 1
1 I ch (_ ~V7^7 / ch d ru/^5 / . c28 ' 1 unless otherwise 11 I —^A-4 A ‘~\ LJn e. audio _L |
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aS W rx-------------n -----------------------
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I / „ f/yx --- 20 . R27 0 35l lock l^ J, L I / rl —J__________________? p? I
VOLTAGE Z TM-------1 CM fe"21'"__VT-145 . 0 meterswitch —--------- SW M S° 4 12 10 6 < 12 10 8 PL >1 Y W 1 I
I REGULATORS _______, ,^xV|? I ---^s 0741-----| -------------------- u ( 5 u PL 4_________________u---------,
I VT-I39 —M. sw'° I2.,ntamlp M rf3 1 L______" J~ § TZ_____________________________©
STa > ---56_ra\SFl j I 'NX°/SK I a int amp \ < <5 ---------------| ------- L-------------------- !
3A -----1 6 d> SWITCHES j pLATE SWo\, V. SWrt --------------------I L—_________________——____________
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I 1 1 I | f-y [ Zj----------------------- I
_____________________________ i^TG^a | +xZ/~ yV ' | POWER overload re^^ overload reset relay”]
i 2 |s 4 5 6 7 s 9 10 11 12 I ~T |_______________I SUPPLY H~V RECT | 14 4 RY 5 "j | RY <4 L. I
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■ - I GNO -1 J |35 OJ g 14 ’ 20M< 3 g ' IO0M< 3 £
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I — QQ 7 OF SO 4 SO a 4r -n so 8 !> J 7 . ------ 3 C ' ~I R F Z) (S ------------- « ,S9503
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M.O. ' T T.oos 9^ 3 I a-h-o_ r34 I t ac
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..4 “"I p"nT'5 ' M -°T T'“ r.f control I -------------------------------—------------------------------------
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.ooeT pow I INT AMPLR t37 -----k T I plate power relay । ow> / > POWER
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| vt-139 ii uLTS Hi I 2..nt amp Bl rpT 1 M?3Ja-L ZJ | § LZ__________________________________
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tZzz^Y—rflG ____lz 1 1 I1 । |
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I ” —————————t 2 4 [71 7 8 9 12 I L—]_______________I I SUPPLY H-V RECT [’ll H RY 5 ~| [ RY2 M P ">
ncM?opMM°) TS I---------------------------------------------* | SECTION VT-46A । I ZTrCZrA Z , 7 S a •
F I 11 I* 'i-ir-f-it | , ___________ ____—- v LE? ?T ZX -J L _ZELlitJ 3
I . 1 & 6 ( i V— e reor r | “
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I VT-46A vVTT.,’4S5 ZLL VT-IOJ L-O’”0 | ---^7' -€,'°0 "'“’so । L ’4"^ St" —1----------yE^^ZX,"
| nropcAP nroPCAP VT-139 L_{j,,,2Q L_ fl,, ,3g. J । ----O1"20 L- -0" ,2[} -40 2 I '°F7 \4ca2( I /) -|-1 i
I - i । ----- Hod___________________________________ I
| VT-218 VT-220 I I -----------------------------------------W-----J I
— -———-J— — — —-— — — _L_—____________ . , I
Figure 122. Radio Transmitter BC-610-E—schematic diagram after change in wiring of interlock switches.
173
?CVX------'K-izvdc £ so20l
X-<3) @ \ T CB 200
/ PE-O95 Arr---------—-----------rF H-| T0 BC-6I0-O ------------------------1
I® SO 200®) break'er ----h n------------
----------/AC--- 50 A ---------O' *=> -----O' CO----
\O^®/ TO HEATER PL 206 Qa 9-------------[]2 A —. POSITIONS OF SW205
/------- SO 203 co T 4 4 £ I. BC-3I2-O
* y? r
S W 206 B & r \~ n "/AC TO LS-3 I— TO I— CW SIDETONE SWITCH
STOP SW >S+Z INCH-121 n BC-3I2-C) [~| C. W. 51DETQNE 5 W l ■ LH.
X +I2V PHONE 2ND|
---------------------- ' AUDIO ----•----1--------------1 _______________
SW2O6A° 1 RECTIFIER PL 203 PL 204 JoL ,1 L I CAPACITORS
START SW •=• RA-63 A J 'U n U 3 ~777
TO SPARE____12-----TO LAMP IN JO ______________J-------------------4 ™G
BATTERY SLOWER CH-121 BC 342 C> SW,.. SW a---------------------
x^xgno r\ 0200 8OOV0C
T° ——(X y V 7 ' " \? J/ x!!/ HEADSET HEADSET C20| 000 V DC
TOBC-312-O BC-342-O BC-3I2-CI BC-342-1) Cj02 200 V DC
so2O4 SO 205 SO 206 so207 SO 208 SO 209 , , , , C203 600 V X
rWi . _jCS_ L/TX, L/TX 0——1 1——D 600vx
> \W/ < ML/, xJ/ vJ/' xji' J202 J204
J 4 j UJ ‘fGND JgND to SPARE TO LAMP TO LAMP . RESISTORS
£ a:* SPARE (ROOF) in CH-120 Fl ’ ,Xfl REF WATTS
tt T 02 3 203 .. J 205 SYMBOL_____
PF-9S “< SsAoLrCEY ’ 7 R200 1/2
A SWITCH R 203 S >*205 ”201 >'2
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o________________ ______________________________________________________________________________________________^204
AUX ________________________ . -I «205 ‘/2
R R----------------------------------------------------------------
200? 201? _____________________________,____________________________________________________
100$ ON 100$ ON ' ~
C 200 } 1 C 201 RECIEvER --------------------------------------------------------------------------
4- —« -• -*■ •—I ) DISABLING
To, suv 200 .01 sw 201 7 SWITCHES
£ '' OFF £ OFF '*~r _____________________________________
~ BC-3I2-1>“ BC-342-<> _____________________________
____________________________________[ '—— — —— — —_____________________________< j TS normal .200 a.
SW203 * »-------b—-----------•' T
POSITIONS OF SW202 _____I f\/7 (-^'hV-i,----------------
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2. rem ph - BC-312-i > i /\5W 204 Tf—t—I—*—¥—T—¥—¥—¥—¥—¥
3 normal TRANS T t 0---------" • •-- V l? 11 10 9876 54321
4 REM PH-BC-342-O ON —T~°------------- A T 2 TRANSPOSE )
5. REM C W-BC-342-O ^-1-0 ~I ^OurpJ^/ (------------->/------------------)
n a 4 O—-----------rT“°------ SWITCH ------7'
REMOTE CONTROL EE-8 SWITCH TRANS T L q *—!—O--------- f ~ L
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£ J ----U 0F all a EE-8-O MIC
I SW O-------------------------------------------£ 320l SOCKETS 4. PRE SS-TO-TAlK
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U J, ’y__________________________________________ a PLATE relay
T _______________________ 7. A C COM
----------------- _ a gnd
NOTE all VALUES ARE in OHMS OR MICROFARADS UNLESS OTHERWISE INDICATED TL-8483A
Figure 124. Junction Box JB-70-A—schematic diagram.
174
TUNING UNIT TU-47 TUNING UNIT TU-48
2.0 TO 2.5 MC 2.5 TO 3.2 MC
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NOTE: ALL PLUG STRIPS PL,0 SHOWN ON PRONG SIDE
TUNING UNIT TU-51 TUNING UNIT TU-52
5.0 TO 6.35 MC 6.35 TO 8.0 MC
Tl 1—I r~l PL|° n Hl Tl : ? Xi pl10 r? Hi o—o 9________o 9 o-—o 9 ° 9
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Figure 127. Radio Transmitter BC-610-E, modulator and power supply chassis—practical rviring diagram.
175
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Figure 126. Radio Transmitter BC-610—E, exciter deck—practical wiring diagram.
176
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Figure 128. Antenna Tuning Unit BC—939—A—practical wiring diagram.
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ARE ON FRONT PANEL. j [ 11 lll| X=^_L । J \ J|°' -----|| T"!
------------—Ftl-lnl------J—F—FS4g^F==FE . -==ee;^zI--------------------
11'I 'll ^^^lZZZZZZZ_______________________________________ I ।____— —-—14—i
<-------------------------III 11 ||l|-------------------------------,---,-----Ht=-----;--------F----
hTZ-~~---^™I LL—l I----lc'20 C|04i ’i ^ = Tp [1
|.rl-——zzj!! / । |i li __
I I Jr ipJ —--------------1—[°=L^—cp>o-{- -j
|l !l i~ll—I—--------------------------------------------------------------------------F=PI------------------
i i—."" 7-rh I JtMfillfW "ZSz-—-] i! rdn-r^a__________
III! ■ Z 11 If—r&2nP^ ~^ry—Ifty?,zz—H L ?i? »|? « §; -----------4;—____________•
lA«ua HtS I' l|_.________A-%fi01 [s X |T—^"'°8 I IY lfl| Y ly ly * “ I r41—qj AJJ II '»5V zs° sv 63 V
l i L2a g rwHL Jo Il
ush.,^ i' ra N_—----------------— -L^---------------Yi ' I I' Lj2;—1’
4L ij-TO-t-l^—1| If ,—---------------------, _ . 'i^—. ttJ._j || F~l
1 il Wn r--------j r==L__ 1 r——
% !Yioi_yi । 11 x5° °7x- \Ery 4^/—] 07 jll h .dZXx---------------
|i IfQ 1 (oZ 8^2 -J —KYcftki-^5745o\ H / Oi oX
Il I J NZUbJ/1 ZL)2. 76ctL (-;=o§>\t104 II fl p
1 < 11 ioJ^fp__u^3--oOJz *^^6*——Vi A6 ?3 i vJjAo7
II \ II---------------FJ'i z rZP-1 I| I——J
|| le-nzAj1 11 ------------—JjjyJ sCsiMj-ti i 11 __
Il lalZ^iST n 4— --------:--::-=h I; X§Lc2L’_-J=T
y J ______________________________________ —Z5--------------11-----------------
•L- . t . n —h---------------------
।—“7® S " ' ।-----------------1 CI28 |—^itaQ Z4 „ 'O/^ \ I
-i-ujn-4----------- ^£X4-J===Z------------------------------- LJSiV—J 11
K-tinn-*-------, - - —---------- r^%2'Q^ _1—-j tp=%oJ:-Uj
Bg-|RI|4 I f- 1-—3 \ J_4 V'O6 r3 5O-— _ rQH|OIQ ________________________
---------------------------J 'L\ p---------------------- M_—_r
.____________________L" |°4 101 2O-|-1
----------------------- I——————-----------—J — -^ -- ■■ ---
2ZO ALL PARTS BELOW THIS LINE-1 /~~l ■= "^a Z~Z j Ma
OJ“ ARE ON REAR APRON. g/-| C|I8 |-A|J rCZL X _L Jl (R137 ) |l ll □ ll RTl
H o’* . \ J " 2 - -
yi V^-i-41 w —jK____J
Figure 129. Speech Amplifier BC-614-E—practical wiring diagram.
SW2OS j ~XX---------swX VC -----1
pOn'' 4T9 rfCSJl ^r^TLJiW^SE Jun) H nJ 7x7 i" hh •xWzil r4 h !!
F^xMd -A- AQ. J -bAAv J^ri iiiiilliT I; remote
;iHl ( /____ HQ J 4 PH p-—"i hi L________J±Z______________I ‘i i telephone
h----------------ii \ ^5=^ —w । _.jj<_X ।1 g —________j ।
l: I'll 1: rW|
!' SW204 |hl zzHzsLhHztjM AzJpx I1 IQJ
7;!! swept il
*^^^7 iinWr EZLSh Ts? l;i Sii W rnh IrM le§ [mhii
---L—r-i —v^--ff—4l-------------
i! nk r—Hl Zff iH'!|ir I'iLiirz:______________________’LL'' — --.
_i; i} 1111 11 ZZZZZZZZZZZZl !ill ।!111 1 11 ---------— “ — 1?
'!r—i|i-lLi|.____ii_________]]i< J । । • 1---.=.=^______zzzzm__________i1 lL
I Tr~ -Frr i~----1 t=3~_~_4 ~ ~'~ ~'~ —: ~ ~ — —tHT" hJil RT J - ii fl
I I Pott ^2 Wx v.-I. L zzx -- --_- z Z.--T - ^ - -- -I.!;1 I r I——1==_ I 11
k i|iliii ’''i i[~ *-i r 1.□ i- . id cl_. n zx *i ii
Fx lli'l'iili;1 ilryyxE ----Ji J \ | Zl________________ |i ii
=i ||i|;il i;;i yijiniAlYl ;i|fef-—ij-JMEx / xi A "
s» ii'iiii!i!1n! innnii! AtST “ )10J) lx sO2O3 4z^»=l4ii! || GXJ ’-------------------------------------------------z5x.
/|(®h U===E3^^4:l±E==2t7h Zxzr xSX J i!
' ZZZZZZZZZZZZZZZZ__ J 41- jg= xred=4 _i । -'■ ■ । T\\x -
XXllWpnig ,t=4h&M1 ?
PL,nW}5>H—------------------—A"? "f " * TO TELEPHONE EE-0-1 ) I \ \ / / I
\9 6 Q/ -------------- 1 -------> IN CHEST CH I2O-A \\. / t.
TpzX -----4 TO RADIO RECEIVER BC- X.^'X X ILIW»
\ ----—] " 11 -------1 342-( )
|__________~ ~ ~ SPEAKER 2D AUDIO -----'
__ ____________________ Q— I C~~1 TO LOUDSPEAKER LS'3 —BLACK—-"’"""”- OPERATION CONTROL CORD_MAIN AUDIO CORD PLUG PL-60 IN CHEST CH-I20-A
Figure 130. Junction Box JB-70-A—practical wiring diagram.
r/7
O o O O
m r.
O r-DiO g
□3
RA50q'O o O O
(~~i —r «
F= =- - - ■ ■ - = =» -BLACK/WHITE TR.'-j
X f *
I-----‘ : => I hl UJ
rrZZZT L______________ 3 u __
£ '------------------7p| 500
H= I “ #----------BLACK/WHITE TR.J I 'U
r' —-------1 0 MlB
pX ' | -■■■ II .-----WHITE/BLUE TR---- Jjr--------------1
----BLACK---------L
*| i1 h §
pT £ £ o o
----- % “ 2 £
2 m3 /T\ 2
t X _I
“ » @ CB5oo
Id
5 r-WHITE/ORANGE TR.-
*
I ____ rm
—if----d | 'S s> | TS50° ||
i gj°=^9----------------40 ep——n—n-K---------70----tjfr t f H3
e ' ______Lg\ (gj 2 l n= _l_--6 ©—4S& 11
V_______Jl_-----------pB ——I —-
J I i===r PL 500
(P* O (^) iff.. SJ TL 18404
Figure 131. Rectifier RA-63-A—practical, wiring dwgram.
178
LINE VOLTAGE-116 V AC APPROXIMATE
TEST FREQUENCY-EMC CW OPERATION
__________________FRONT EDGE OF R F EXCITER PECK ■
SOOV DC y ^*\
• / VT-isa \
~ n O G / b J \
I--------------- CMi| |— isov DC -^*1227 ------------ / «Q ~ O' \
'—-6 SV AC -----| /jO ° 'X \3P °2 /
9 >° ° i° o 061 X\° °5X
440 V DC ---x I rO U Or-/ 6 S V AC , /
<" J3 O-----------I60V0C O O—-Z_ 150 V DC ,
440 V DC --- XJ ~~l SV DC
” £> O--------------------1 '----------------------' VT-139
440 V DC---- Z-——. '
R- O--------------ioo v ac -1 A O O \
X r. r. O C7O'\
-160 V DC <0. - 3l0VDC->/A6 300 V DC \ O 02/
O-------------------1 AY>° °77\-----65ViC—I X.«° 8 Xisovdc
(v O r— «» °C x-------x
V ■ >O o----------6T0VAC ---1 \*0 O, /
I---------------' i-----------------A—O O—/----------------1 JOi?
ki r) o J Al
I-- 5VAC ---------- G f. O O \
~o° CMs c I ° (7°'I
r 150 V DC \ ’o Oz /
- o o 1 \ P O. /
• vt-ioo \* \y
440 V DC s'"--------------------------------------------------
— - / O \ '
- “ r-----------------b° H-------------------1
< \ O-y-----6 SV AC--- — S VAC ---1—
R?l | /XX . r-f—-----------------------—
•? 320 V DC
1 _ n n n
I----Y PLATE (g)-----' 0 00 ’-*440 V DC 1 11 ‘ I—>
G VT-IOO 46OV0C-^ J
-180 DC . CHt£ I RE2 /AdlX. _________________ ''"0 Q U
rg-g-jp X \ J / oA-------------
\ c*e * \ ° o / rO □ Eh
\ - 200 V DC \ Y /
>l-2grio SEOVOC g~HAsVAC J / ' ! D T
VT-220 VT-145 M50 V DC 4480 V DC lOOVAC
O I ।--------------------Z-o O~\----5VAC ----1 6 3 V AC
\ o 7 u
L- 870 V AC---------O 0-7-------------1
----5V AC----- *“
PC'7 q qCI6
48ov dc —I T T A
450 V DC ' X480 V DC
SOCKET VIEWS ARE BOTTOM VIEWS
NOTE ALL VOLTAGES MEASURED WITH 1,000 OHM PER VOLT VOLTMETER IN ANALYZER BC-IO52-E SUPPLIED WITH RADIO SET SCR-399-A
VOLTAGES MEASURED TO GROUND UNLESS OTHERWISE INDICATED
TL l«40?
Figure 132. Radio Transmitter BC-610-E, exciter deck3 voltages at tube sockets and terminal strips.
179
_ *________________________________________erqnt edge of modulator chassis___________________
117 V AC ——
-«ovoc —। -fl I® ,\~IT5 V D.C \~T~435 v AC __pJ5vAC
C2j c20 =1 5s/) A I’ T h Ci C °=
' J 7 I’ “I fle kl [2 05 a“ | T’
x'-" Aso/ * j j" > p D?
2 « S“ ' -9OVDC SOj so_ ro 435 v AC
"» I
- 380 VDC -. r -380 V DC * l~360 V DC
Q a 0 G *• ?)
E-90V.DC -400 VDC -360-'SC .J-300 V DC
■ITS VDC- PHONE PHONE -300 VDC ______, 7 500 VAC
*'______-40VDC-- Tt> 40 VDC T3 300 VOC ______T| ^OOVAC
50-6 OC I-1
□ Q -360 VDC -------OF------------------360 VDC □ □ □ SrA , |-> rj
CW G C CW ST 100 115 «LI m Ln Ll Li-
on He -360 V DC Q^-— -360 VDC Lg o - g
C-360 V DC *3S0VDC ' - \ PHONE---------------------------PHONE rd X S □ -7VDC-□ □ □ TV DC O O \ I / \__/ / \
I \o-, J/ \<5 r«/ I L \ \Q q/
2-5 VAC X1 J V V |tL_2.5VDC \ \
\ / \ / ---------' -------L-5VAC
\ / \ / VT-218 V7-2.«
\_y W VT-145
VT-95 VT-95
SOCKET VEWS ARE BOTTOM VIEWS
NOTE: ALL VOLTAGES MEASURED WITH 1,000 OHM PER VOLT VOLTMETER IN ANALYZER BC-IO52-E SUPPLIED WITH RADIO SET SCR-399-A VOLTAGES MEASURED TO GROUND UNLESS OTHERWISE INDICATED TL 16411
Figure 133. Radio Transmitter BC-610-E, modulator deck, voltages at tube sockets and transformer^
180
FRONT EDGE; OF POWER SUPPLY CHASSIS
BOTTOM VIEW OF POWER SUPPLY
NOTE! ALL VOLTAGES MEASURED WITH 1,000 OHM PER VOLTMETER IN ANALYZER BC-IO52-E SUPPLIED WITH RADIO SET SCR’399 “ A
VOLTAGES MEASURED TO GROUND UNLESS OTHERWISE INDICATED
Figure 134- Radio Transmitter BC-610--E, power-supply deck, voltages at tube sockets and transformers.
2000 V DC PHONE
O 25CO V DC CW
2160 V DC PHONE
O 2600 V DC C
2160 V DC PHONE
26 00 V DC CW |-------------------100 VAC-----------
--------------------------(k
os EH----------------------------
----25 V AC--------------O S ?□
2160 V DC PHONE 2160 V DC PHONE
—~^2600 V DC CW "—--^ 2600 V DC CW
2 5V AC j | j—2 5 V AC
/Z
। । i r ।
\ r a '
.... ' — ----------------------------------'_________
VT-46A VT-46A
J83
VT- 94 VT-231 VT- 80
____ O45VOC^. 76 V DC . _____,240V0C _____
6VDC TI64 I-------Z)o\
fO \ VT-231 /Q) O 0>~r ---------
Zp ,Q/ \ /O Q\ 240 V DC Zp oQ/\ O J/
\ \ U"> rJ "Ls.3VAcX * *0 *0 ’Q -^265 V DC
22.5VDC -s L63VAC J V/-30VDC _____-___________
z^6j VAC —F~~7^ - 1.2 V o C
250 V DC -- -----------265 V DC
TIOI TIO2 CMlOl
□s ’□ D3 ’□
□ □ □
VT-231 VT-233
8.7 V DC 25 V DC -\
□« >□ D' 40 Fax
50 V DC -x/\O o) '■6 sdcV (q Oyle.SVAcX
"Zp Tp 2p>/
8 7 V DC ----15 0 V DC ----
SOCKET VIEWS ARE BOTTOM VIEWS
NOTE all VOLTAGES MEASURED WITH 1,000 OHM PER VOLT VOLTMETER IN ANALYZER BC-IO52-E SUPPLIED WITH RADIO SET SCR-399 A
VOLTAGES MEASURED TO GROUND UNLESS OTHERWISE INDICATED TL 16412
»
Figure 135. Speech Amplifier BC-614-E, voltages from tube sockets to chassis.
182
AP PENDIX I
MAINTENANCE PARTS LIST
For maintenance parts information, see appropriate sections of Army Service Forces Catalogs SIG-7 SCR-399 and SIG-7 SCR-499, Organizational Spare Parts, and SIG-8 SCR-299, SCR-399, SCR-499, Higher Echelon Spare Parts.
183
APPENDIX II
REFERENCES
I. Parts List
SIG 1
SIG 2
SIG 3
SIG 4-1
SIG 4-2
SIG 5
SIG 6
SIG 7
SIG 8
SIG 8
SIG 8
SIG 8
SIG 8
SIG 8
SIG 8
SIG 8
SIG 8
SIG 8
SIG 8
SIG 8
SB 11-8
SB 11-10
Introduction to ASF Signal Supply Catalog (when published).
Complete Index to ASF Signal Supply Catalog (when published).
List of Items for Troop Issue.
Allowances of Expendable Supplies.
Allowances of Expendable Supplies for Schools, Training Centers, and Boards.
Stock List of all Items.
Sets (when published).
Organizational Spare Parts.
Higher Echelon Spare Parts for Radio Sets SCR-399-A and SCR-499-A.
Higher Echelon Spare Parts for Radio Receivers BC-312-( ) and BC-342-( ).
Higher Echelon Spare Parts for Radio Transmitter BC-610.
Higher Echelon Spare Parts for Speech Amplifier BC-614-( ).
Higher Echelon Spare Parts for Antenna Tuning Unit BC-939-A.
Higher Echelon Spare Parts for Telephones EE-8-( ).
Higher Echelon Spare Parts for Headset HS-30- ( ).
Higher Echelon Spare Parts for Shelter HO-17.
Higher Echelon Spare Parts for Junction Box JB-70-A.
Higher Echelon Spare Parts for Power Unit PE-95-A, B, C, D.
Higher Echelon Spare Parts for Frequency Meter Set SCR-211-( ).
Higher Echelon Spare Parts for Microphone T-30- ( ).
Chests for Running Spares.
Signal Corps Kit and Materials for Moisture and Fungi-Resistant Treatment.
2. Technical Manuals on Auxiliary Equipment and Test Equipment
TM 11-300 Frequency Meter Sets SCR-211-A, SCR-211-B, and SCR-211-C
TM 11-303 Test Sets I-56-C, I-56-D, I-56-H, and I-56-J.
TM 11-307 Signal Generators I-72-G, I-72-H, and I-72-J.
TM 11-321 Test Set I-56-E.
TM 11-2613 Voltommeter 1-166.
TM 11-2626 Test Unit 1-176.
TM 11-2627 Tube Tester 1-177.
TM 11-472 Repair and Calibration of Electrical Measuring Instruments.
3. Painting, Preserving, and Lubrication
SB 11-10 Signal Corps Kit and Materials for Moisture and Fungi-Resistant Treatment.
4. Shipping Instructions
U. S. Army Army-Navy General Specification for Packaging and Packing for Oversea Spec No. Shipment.
100-14A
5. Decontamination
TM 3-220
6. Demolition
FM 5-25
Decontamination.
Explosives and Demolitions.
7. Camouflage
FM 5-20
Camouflage, Basic Principles.
184
8. Other Technical Publications
FM 21-6 List of Publications for Training.
FM 21-7 List of War Department Films, Film Strips, and Recognition Film Slides.
FM 21-8 Military Training Aids.
FM 21-40 Defense Against Chemical Attack.
FM 24-6 Radio Operator’s Manual, Army Ground Forces.
FM 24-11 Combined Operating Signals.
FM 24-18 Radio Communication.
TB SIG 5 Defense Against Radio Jamming.
TB SIG 13 Moistureproofing and Fungiproofing Signal Corps Equipment.
TB SIG 25 Preventive Maintenance of Power Cords.
TB SIG 66 Winter Maintenance of Ground Signal Equipment.
TB SIG 69 Lubrication of Ground Signal Equipment.
TB SIG 72 Tropical Maintenance of Ground Signal Equipment.
TB SIG 75 Desert Maintenance of Ground Signal Equipment.
TB SIG 143 Installation Instructions for Vehicular Radio Sets.
TM 1-455 Electrical Fundamentals.
TM 11-227 Signal Communication Equipment Directory, Radio Communication Equipment.
TM 11-300 Frequency Meter Set SCR-211-( ).
TM 11-310 Schematic Diagrams for Maintenance of Ground Radio Communication Sets.
TM 11-314 - Antennas and Antenna Systems.
TM 11-333 Telephones EE-8, EE-8-A and EE-8-B.
TM 11-430 Batteries for Signal Communication Except those Pertaining to Aircraft.
TM 11-453 Shop Work.
TM 11-454 The Radio Operator.
TM 11-455 Radio Fundamentals.
TM 11-462 Signal Corps Reference Data.
TM 11-483 Suppression of Radio Noises (when published).
TM 11-496 Training Text and Applicatory Exercises for Amplitude-modulated Radio Sets.
TM 11-499 Radio Propagation .Handbook.
TM 11-904-H Power Units PE-95-G and PE-95-H.
TM 11-850-N Radio Receivers BC-312-N, BC-312-NX, BC-342-N, BC-314-G, and BC-344-D.
TM 11-2737 Installation of Radio and Interphone Equipment in Shelter HO-17 (when published).
TM 38-250 Basic Maintenance Manual.
9. Forms
Unsatisfactory Equipment Report. (See fig. 151.)
10. List of Abbreviations
a-c....................................................... alternating-current
a-f....................................................... audio-frequency
a-v-c .................................................... automatic-volume-control
BFO ...................................................... beat-frequency-oscillator
cps....................................................... cycles per second
c-w ...................................................... continuous-wave
db ....................................................... decibel (s)
d-c....................................................... direct current
h-f....................................................... high-frequency
i-f ...................................................... intermediate-frequency
i-p-a .................................................. intermediate-power-amplifier
kc........................................................ kilocycle (s)
1-f ...................................................... low-frequency
ma........................................................ milliampere(s)
me........................................................ megacycle (s)
mmf ...................................................... micromicrofarad (s)
m-o ...................................................... master-oscillator
m-v-c................................... ................. manual-volume-control
185
„_a ................................................. power-amplifier
\ ............... ,............... radio-frequency
I I. Glossary
See glossary, TM 11-455.
186
Table VIII. Continuity checks for cables and terminal strips
a. Radio Transmitter BC-610-E
Measured from Ref symbol Term or lead No. Action or condition Measured to Resistance (in ohms)
Plug PLi (in modulator) PL! 7 8 Remove plug PLi from socket SOi Remove plug PLi from socket SOi Terminal 1 of terminal strip TSi ' Terminal 3 of terminal 0 0
9 Remove plug PLi from socket SOi strip TSi Terminal 4 of terminal 0
11 Remove plug PLi from socket SOi strip TSi Terminal 5 of terminal 0
strip TSi
Plug PL2 (in modulator) pl2 7 8 Remove plug PL2 from socket SO2 Remove plug PL2 from socket SO2 Terminal 7 of terminal strip TSi Terminal 8 of terminal 0 0
10 Remove plug PL2 from socket SO2 strip TSi Terminal 10 of terminal 0
11 Remove plug PL2 from socket SO2 strip TSi Terminal 9 of terminal 0
12 Remove plug PL2 from socket SO2 strip TSi Terminal 11 of terminal 0
strip TSi
Plug PL3 'in Modulator) pl3 1 Fuse FS5 in operating condition. Remove plug PL3 from socket SO3 Terminal 5 of terminal strip TS3 0
1 Fuse FS.5 in operating condition. Remove plug PL3 from socket SO3 Terminal 5 of plug PL3 0
1 Fuse FS5 in operating condition; lamp LM3 in its socket. Remove plug PL3 from socket SO3 Terminal 6 of plug PL3 Note. Setting of potentiometer Bis varies resistance reading. 9-21
1 Fuses FSi and FS5 in operating condition; lamp LM3 in its socket; switch SWi at ON. Remove plug PL3 from socket SO3 Terminal 3 of plug PL3 Note. Setting of potentiometer Ris varies resistance reading. 9-21
1 Fuse FSs in operating condition; lamp LM3 in its socket; switch SW6 at ON. Remove plug PL3 from socket SO3 and plug PL4 from socket SO4 Terminal 11 of plug PL4 Note. Setting of potenti-ometer Ris varies resistance reading. 9-21
1 Fuse FSs in operating condition; lamp LM3 in its socket; switch SW3 at ON. Remove plug PL3 from socket SO3 and plug PL4 from socket SO< Terminal 12 of plug PL4 Note. Setting of potentiometer Ris varies resistance reading. 9-21
1 Switch SW7 at PHONE; fuse FSs in operating condition. Remove plug PL3 from socket SO3 Terminal 2 of plug PL3 0
4 Terminal 4 of terminal 0
4 4 Switch SW12 closed. Remove plug PL3 from socket SO3 Potentiometer Ri8 full counterclockwise. Remove plug PL3 from socket SO3 strip TS3 Terminal 6 of terminal strip TS3 Terminal 6 of plug PL3 0 15
5 Fuses FS2 and FS4 in operating condition. Remove plug PL3 from socket SO3 Terminal 7 of plug PL3 0
7 Fuses FS2 and FS3 in operating condition; lamp LMi in its socket. Remove plug PL3 from socket SO3 and plug PLi from socket SO4 Terminal 7 of plug PL.» 340
7 Fuses FS2 and FS3 in operating condition; lamp LM4 in its socket; switch SWi at NORMAL. Remove plug PL3 from Terminal 8 of plug PL4 .1
socket SO3; remove plug PL< from socket SO 4
7 Fuses FS2 and FS3 in operating condition; lamp LMi in its socket; switch SW4 at NORMAL. Remove plug PL3 from socket SO3 Terminal 1 of terminal strip TS3 .1
7 Fuses FS2 and FS3 in operating condition; switch SW7 at C.W. Remove plug PL3 from socket SO3 Terminal 2 of terminal strip TS3 0
7 Fuses FS2 and FS3 in operating condition; switch SW7 at PHONE. Remove plug PL3 from socket SO4 Terminal 3 of terminal strip TS3 0
8 Remove plug PL3 from socket SO3 Terminal 7 of terminal 0
strip TS3
187
a. Radio Transmitter BC-610-E (Contd.)
Measured from Ref symbol Term or lead No. Action or condition Measured to Resistance (in ohins)
Plug PL4 (in modulator) PL4 9 9 Remove plug PL4 from socket SO 4 Potentiometer R12 full clockwise. Remove plug PL4 from socket SO4 Ground or chassis Terminal 10 of plug PL4 500 500
Plug PLn (on meter panel) • 1 2 3 4 G 7 8 Remove plug PLn from socket SOu Remove plug PLn from socket SOn Remove plug PLn from socket SOn Remove plug PLn from socket SOn Remove plug PLn from socket SOn Remove plug PLn from socket SOn Remove plug PLn from socket SOn Remove’plug PLn from socket SOn Terminal 5 of terminal strip TS2 Terminal 8 of terminal strip TS2 Terminal 6 of terminal strip TS2 Terminal 9 of terminal strip TS2 Terminal 7 of terminal strip TS2 Terminal 10 of terminal strip TS2 . Terminal 12 of terminal strip TS2 Terminal 11 of terminal strip TS2 0 0 0 0 0 0 0 0
Socket SO 1 (in modu- SOt 7 Remove plug PLi from socket SOi Ground or chassis 0
lator) 8 9 Remove plug PLi from socket SOi Remove plug PLi from socket SOi Terminal 2 of socket SO 5 Terminal 11 of socket SO 1 0 85
Socket SO2 (in modulator) SO2 7 7 7 10 11 Remove plug PL2 from socket SO2; remove plug PL3 from socket SO3 Remove plug PL2 from socket SO2 Remove plug PL2 from socket SO2; remove plug PL3 from socket SO3 Remove plug PL2 from socket SO2; remove plug PL4 from socket SO4 Remove plug PL2 from socket SO2 Terminal 4 of socket SO3 Terminal 8 of socket SO2 Terminal 5 of socket SO3 Terminal 11 of socket SO 4 Tap on resistor Ri 1 0 3 3 0 0
Socket SO3 (in modu- SO3 1 Remove plug PL3 from socket SO3 Terminal 6 of socket SO3 1.5
lator) 1 1 2 3 7 Remove plug PL3 from socket SO3 Remove plug PL3 from socket SO3 Remove plug PL3 from socket SO3 Remove plug PL3 from socket SO3 Remove plug PL3 from socket SO3 Terminal 1 of socket SO 5 Terminal 3 of socket SO 5 Terminal 6 of socket SO3 One side of socket SOo Other side of socket SOo 0 1.5 280 0 0
Socket SO4 (in modulator) SO4 7 9 10 11 Remove plug PL4 from socket SO4 Remove plug PL4 from socket SO4 Remove plug PL 4 from socket SO 4 Switch SW5 closed. Remove plug PL3 from socket SO3; remove plug PLi from socket SO 4 Terminal 8 of socket SO4 Terminal CT of transformer Ti (2.5-volt winding). An open bias voltage contact on relay RY3 Terminal 8 of socket SO 3 10 3,200 0 80
Socket SO5 (in modulator) SO 5 8 6 5 4 Remove plug PL4 from Socket SO4 Ground or chassis Terminal 7 of socket St) 5 Terminal 8 of socket SO 5, ground, or chassis Terminal 11 of socket SO 4 0 37 180 0
Sockets SO7, SO8, * and SO9 (in tuning SO7 1 Switch SWn at position 1 Terminal 5 of tube Vs (JAN-6V6) 0
unit) SO7 1 Switch SWi i at position 2 or 3 Ground or chassis 0
SOs 1 Switch SWn at position 2 Terminal 5 of tube Vs (JAN-6V6) 0
so8 1 Switch SWn at position 1 or 3 Ground or chassis 0
SO9 1 Switch SWn at position 3 Terminal 5 of tube Vs (JAN-6V6) 0
SO9 1 Switch SWn at position 1 or 2 Ground or chassis 0
SO-) . . • ■ — —- - —>•
SO8 SO9J 2 Ground or chassis 0
188
a. Radio Transmitter BC-610-E (Contd.)
Measured from Ref symbol Term or lead No. Action or condition Measured to Resistance (in ohms)
Socket SO7, SO8, ?nd SO9 (in tuning unit) (Contd.) Socket SO 11 (on upper control panel) Terminal strip TSi SO7 so8 so9 so7) so8 SO9J SO7 SO7 so8 so8 so9 SO9 SO7) so8 SO9 SO7 SO8) SO9J SO7 so8 so9 SO7 SO8 so9 SOu TSi 4 4 4 7 8 8 8 8 8 8 10 11 11 11 11 12 12 12 1 2 2 3 7 8 1 1 1 1 1 1 3 4 5 Switch SW11 at position 1 Switch SWn at position 2 Switch SWn at position 3 Switch SWn at position 1 Switch SWn at position 2 or 3 Switch SWn at position 2 Switch SWn at position 1 or 3 Switch SWn at position 3 Switch SW11 at position 1 or 2 Switch SWn at position 2 or 3 Switch SWn at position 1 or 3 Switch SWn at position 1 or 2 Switch SWn at position 1 Switch SWn at position 2 Switch SWn at position 3 Meter switch SW8 at DOUBLER PLATE. Remove plug PLn from socket SOn Meter switch SW8 at DOUBLER PLATE. Remove plug PLn from socket SOn Meter switch SW8 at DOUBLER PLATE. Remove plug PLn from socket SOn Meter switch SW8 at DOUBLER PLATE. Remove plug PLn from socket SOn Remove plug PLn from socket SOn Remove plug PLn from socket SOn Remove tube Vie from its socket Remove tube Vie from its socket Remove lamp LM2 from its socket. Remove plug PLn from socket SOn One side only of capacitor Ci One side only of capacitor C1. One side only of capacitor Ci Terminal 9 of terminal strip TS2 Terminal 3 of socket for tube V9 (JAN-6L6) Terminal 7 of sockets SO8 and SO9 Terminal 3 of socket for tube V9 (JAN-6L6) Terminal 7 of sockets SO7 and SO9 Terminal 3 of socket for tube V9 (JAN-6L6) Terminal 7 of sockets SO7 and SO8 Ground or chassis Terminal 10 of terminal strip TS2 Terminal 12 of socket SO7 Terminal 12 of socket SO8 Terminal 12 of socket SO9 Plate caps of tubes V10 and V11 Plate caps of tubes V10 and V11 Plate caps of tubes V10 and V11 Terminal 3 of socket SOn Terminal 4 of socket SOn Terminal 6 of socket SOn Terminal 5 of socket SOn Ground or chassis One side of socket for lamp LMi Ground or chassis Terminal 8 of terminal strip TS2 Terminal 12 of terminal strip TS2 Terminal 3 of terminal strip TS2 Terminal 4 of terminal strip TS2 Terminal 11 of terminal strip TS2 Terminal 8 of socket for tube V8 (JAN-6V6) Terminal 2 or 3 of socket for tube V12 (JAN-5Z3) Terminal 2 or 3 of socket for tube V12 (JAN-5Z3) 0 0 0 20 0 0 0 0 0 0 0 20 0 0 0 0 0 0 .6 .6 .4 500 0 0 0 35,000 0 0 0 4 0 70 0 0
189
a. Radio Transmitter BC-610-E (Contd.)
Measured from Ref symbol Term or lead No. Action or condition Measured to Resistance (in ohms)
Terminal strip TSi (Contd.) Terminal strip TS2 TS2' 7 9 10 3 4 5 7 9 10 12 Tubes V13, V14, V15 in their sockets Switches SW2, *SWio, SW13 closed Terminal 8 of terminal strip TSi Terminal 6 of terminal strip TS2 Terminal 11 of terminal strip TSi One side of meter M3 Other side of meter M3 Grid connection of tube V16 Terminal 3 of sockets for tubes V10 and Vn Terminal 4 of socket for tube V9 Terminal 2 of sockets for tubes V10 and V11 Ground or chassis 1.0 0 0 0 0 20 5,000 50,000 20,000 0
Terminal strip TS3 ts3 1 2 3 4 4 6 8 8 9 Relay RY2 at normal Terminal 0 of transformer t6 Terminal 2600 of transformer Te Terminal 2000 of transformer Te Terminal 5 of terminal strip TS3 Terminal 7 of terminal strip TS3 An open contact on relays RY2 and RY5 Ground or chassis Aside of meter M2 Ground or chassis 0 0 0 1 3 775 75,000 0 0
* SWio was omitted on models beginning with Serial No. 5191 on Signal Corps Order No. 30204-P-44 and on all transmitters thereafter.
b. Speech Amplifier BC-614-E
Measured from Ref symbol Term or lead No. Action or condition Measured to Resistance (in ohms)
Socket SO101 (marked DYNAMIC MIC. 8) SO101 1 2 Ground or chassis Terminal 4 of socket SO102 0 0
- 2 3 * . Tip contact of jack J102 Terminal 3 of socket SO102 0 500,000
Socket SO 102 SO102 1 2 2 5 6 7 7 Terminal 3 or 6 of tube V106 (JAN-6N7) Tip contact of jack J101 Terminal 2 of socket SO103 Ground or chassis - Terminal 4 of socket SO103 Terminal 3 of socket SO103 Terminal 1 of socket SO 103 500 0 0 7,000 0 0 16
•8 Ground or chassis 0
Socket SO103 SO 103 5 6 6 8 Positive terminal of meter M101 Ground or chassis Terminal 7 of socket SO103 Ground or chassis 0 35 35 0
Transformer Tjos T103 CT CT Insert dummy phone plug in Jack J102 Ground or chassis Ground or chassis 311 511 *375
* This reading applied on all Signal Corps orders except Signal Corps Order No. 14153-P-43.
190
c. Junction Box JB-70-A
Measured from Ref symbol Term or lead No. Action or condition Measured to Resistance (in ohms)
Terminal strip TS2eo Note. Disconnect all in Plug PL200 Plug PL201 (to Loudspeaker LS-3 in Chest CH-20) Plug PL202 (to BC-342 PHONE 2ND AUDIO) Socket SO200 (power input) TS200 erconnectin PL200 PL201 PL202 SO200 1 3 3 6 6 8 12 12 12 g cables wh 1 2 3 4 5 6 7 8 Tip Sleeve Tip Sleeve 1 2 2 2 3 3 3 3 3 3 3 3 3 Switch SW203 at TRANS. ON Switch SW205 at TO BC-312 or TO BC-342 Hold relay RY200 closed Switch SW202 at position 1, 3, or 5 Switch SW202 at position 2, or 4; switch SW203 at TRANS. ON en making the following checks except connections to Receiver output transpose switch in NORMAL position Press STOP button to close switch SW206A Switch SW207 at PE-95 Switch SW207 at PE-95 Switch SW207 at PE-95; switch SW200 at BC-312 ON. Hold relay RY2oo closed Switch SW207 at PE-95; switch SW201 at BC-342 ON. Hold relay RY200 closed Switch SW207 at PE-95; switch SW200 at ON. Hold relay RY200 closed Switch SW207 at PE-95; switch SW201 at ON. Hold relay RY200 closed Switch SW207 at PE-95; switch SW203 at TRANS. ON Switch SW207 at PE-95; switch SW203 at TRANS. ON. Switch SW202 at position 1 or 5 Switch SW207 at PE-95; switch SW203 at TRANS ON; switch SW202 at position 2 or 4 Terminal 2 of terminal strip TS200 Terminal 4 of terminal strip TS200 Ground or chassis Ground or chassis Terminal 11 of terminal strip TS200 Terminal 12 of terminal strip TS200 Other side of EE-8 in chest CH-120 Sleeves of jacks J200, J201, J202, J203, J204, and J205 Ground or chassis terminal strip TS200. Terminal 4 of terminal strip TS200 Terminal 3 of terminal strip TS200 Terminal 6 of terminal strip TS200 Terminal 7 of terminal strip TS200 Terminal 5 of terminal strip TS200 Terminal 2 of terminal strip TS200 Terminal 1 of terminal strip TS200 Terminal 8 of terminal strip TS200 Terminal 9 of terminal strip TS200 Terminal 12 of terminal strip TS200 Terminal 9 of terminal strip TS200 Terminal 12 of terminal strip TS200 Terminal 4 of socket SO200 One side of sockets SO201 and. SO202 One side of sockets SO207, SO208, and SO209 A-c contact of socket SO203 Terminal 4 of socket SO204 Terminal 7 of terminal strip TS200 Terminal 2 of socket SO204 Terminal 2 of socket SO205 Terminal 2 of socket SO204 Terminal 2 of socket SO205 Tip contact of jacks J200 and J201 One side of the remote line Ground or chassis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 200 0 0 0 0 100 100 100
191
c. Junction Box JB-70-A (Contd.)
Measured from Ref symbol Term or lead No. Action or condition Measured to Resistance (in ohms)
Socket SO200 (power input) (Contd.) 4 5 Ground or chassis One side of sockets SO201 0 0
5 5 and SO202 One side of duplex sockets SO207, SO208, and SO209 One a-c terminal of 0 0
6 Press START button to close switch socket SO203 Terminal 4 of socket 0
SW206A SO200
Socket SO203 (on Rectifier RA-63-(*) ) SO203 + 12V Switch SW207 at AUX Terminal 4 of socket SO204 0
Socket SO204 SO204 1 One side of the remote 0
line
1 Ground or chassis 0
3 Ground or chassis 0
Socket SO205 SO205 1 Ground or chassis 0
3 Ground or chassis 0
Socket SO206 (duplex spare) SO206 Either GND terminal Ground or chassis 0
Socket SO210 (audio cord) SO210 1 ' ■ 1 Switch SW205 at TO BC-312 Tip contact of jacks J202 and J203 Terminal 5 of terminal 5,000 5,000
1 Switch SW204 at NORMAL strip TS200 Terminal 2 of socket 0
1 Switch SW204 at TRANSPOSE SO210 Terminal 10 of terminal 0
2 Switch SW204 at TRANSPOSE strip TS200 Terminal 9 of terminal 0
2 Switch SW204 at TRANSPOSE strip TS200 Tip contact of jacks J204 5,000
2 Switch SW205 at TO BC-342; switch and J205 Terminal 5 of terminal 5,000
3 SW204 at TRANSPOSE strip TS200 Ground or chassis 0
4 Ground or chassis 0
_
192
Table IX. Data for checking transformers, chokes, and inductors
Note. Resistances of less than 1 ohm are given as 0. All measurements are made with windings disconnected from the associated circuit.
a. Radio Transmitter BC-610-E and Antenna Tuning Unit BC-939-A.
Ref Windings D-c Inductance
Component symbol or resistance (in
terminals (in ohms) microhenries)
R-f choke CHi 20 1,000
R-f choke CH2 20 1,000
R-f choke CH 3 32 2,500
R-f choke ch4 8.5 2,500
R-f choke ch5 20 1,000
R-f choke ch6 20 1,000
R-f choke ch7 20 1,000
R-f choke ch8 20 1,000
R-f choke ch9 42 10,000
Filter choke Li 90 6 x 106
Filter choke l2 125 6 x 10°
Filter choke L3 125 6 x 106
Filter choke l4 58 11 x 106
Antenna coupling coil L5 1.8
Antenna loading coil Le 100
Coil Unit C-387-B L7 58
Cod Unit C-388-A L7 32
Coil Unit C-389-A l7 18
Coil Unit C-390-A l7 12
Coil Unit C-447 l7 5.9
Coil Unit C-448 l7 3.5
Coil Unit C-449 l7 2
Antenna loading coil l44 14
Tuning unit
M-o grid coil TU-47 l8 89
M-o grid coil TU-48 l9 55.5
M-o grid coil TU-49 Lio 41.0
M-o grid coil TU-50 Li 1 21.4
M-o grid coil TU-51 L12 14.1
M-o grid coil TU-52 L13 7.4
Crystal-oscillator cathode coil TU-47 Li4 37
Crystal-oscillator cathode coil TU-48 L15 19
Crystal-oscillator cathode coil TU-49 Lie 9.2
Crystal-oscillator cathode coil TU-50 L17 66.0
Crystal-oscillator cathode coil TU-51 Lis 22.8
Crystal-oscillator cathode coil TU-52 L19 18.0
Buffer-doubler plate coil TU-47 L2q 40
Buffer-doubler plate coil TU-48 L2i 30.8
Buffer-doubler plate coil TU-49 l22 20.6
Buffer-doubler plate coil TU-50 L23 12.6
Buffer-doubler plate coil TU-51 l24 8.6
Buffer-doubler plate coil TU-52 L25 5.66
Intermediate-amplifier plate coil TU-47 L26 40
Intermediate-amplifier plate coil TU-48 l27 30.8
Intermediate-amplifier plate coil TU-49 L28 20.6
Intermediate-amplifier plate coil TU-50 l29 12.6
Intermediate-amplifier plate coil TU-51 L30 8.6
Intermediate-amplifier plate coil TU-52 L31 5.66
M-o grid coil TU-53 L32 7.5
Buffer-doubler plate coil TU-53 L33 2.56
Intermediate-amplifier plate coil TU-53 l34 2.56
M-o grid coil TU-54 L35 12.7
Buffer-doubler plate coil TU-54 L36 4.84
Intermediate-amplifier plate coil TU-54 L37 1.15
Crystal-oscillator cathode coil TU-53 L41 8.0
Crystal-oscillator cathode coil TU-54 L42 14.2
Power transformer Ti 500-0-500-volt secondary; 135
117-volt primary; 1.5
2.5-volt, 5.0-amp secondary. 0
5.0-volt, 3.0-amp secondary 0
Filament transformer t2 117-volt primary; 11
100-volt primary; 10
2.5-volt 10-amp secondary 0
Filament transformer t3 100-volt primary; 3
5-volt, 16-amp secondary 0
Power transformer t4 100-volt primary; 2.0
5-volt, 10.5-amp secondary 0
193
a. Radio Transmitter BC-610-E and Antenna Tuning Unit BC-939-A (Contd.).
Component Ref symbol Windings or terminals D-c resistance (in ohms) Inductance (in microhenries)
Power transformer (Contd.) 6.3-volt, 3.5 amp secondary; 0
5-volt, 3-amp secondary 0
Power transformer t5 115-volt primary; 1.5
435-0-435 secondary 85
Power transformer t6 2,000-volt primary tap; 0
2,600-volt primary tap; 0
total secondary 140
Audio transformer T'z 500 line primary; 35
G to G secondary; 950
G to CT secondary 475
Audio transformer t8 P to P primary; 250
P to CT primary; 125
G to G secondary; 170
G to CT secondary 85
Modulation transformer t9 P to P primary; 300
P to B primary; 150
P to B + secondary 135
Relay winding RYi* 540
Relay winding RYi 97
Relay winding ry2 780
Relay winding ry3 280
Relay winding RY 4 480
Relay winding RY 5 6
* Supplied with Signal Corps Orders Nc. 14153—Phila—43 and 30204—Phila—43 only.
b. Speech Amplifier BC-614-E.
Component Ref symbol Windings or terminals D-c resistance (in ohms) Inductance (in microhenries)
Audio transformer Tioi 1 to 2; 11
3 to 4 13.5
Audio transformer T102 1 to 3; 2 to 3; or 660
1 to 2; 330
4 to 5 35
Power transformer T103 115-volt primary; 16
6.3-volt, 2-amp secondary; 0
5-volt, 2-amp secondary; 0
250-250 secondary 600
Audio transformer T104 2 to 3; 3,750
8 to 5; 8 to 7; or 8,500
6 to 5 4,500
Filter choke CHj 700 29
c. Junction Box JB-70-A.
Component Ref symbol Windings or terminals D-c resistance (in ohms) Inductance (in microhenries)
Relay winding .RY2oo 200 1.5
194
Table X. Performance Characteristics
Description Indicating meter Meter switch position Normal Limits
Maximum Minimum
Line voltage (a-c) Filament voltage Buffer-doubler plate current Intermediate-amplifier grid current Intermediate-amplifier plate current P-a grid current (PLATE POWER OFF) P-a grid current (PLATE POWER ON) P-a plate current (PHONE) P-a plate current (C.W.) Modulator plate current (no modulation) Modulator plate current (100% modulation) Power output (voice) (4 me) Power output (c-w) FIL. VOLTAGE EXCITATION METER EXCITATION METER EXCITATION METER EXCITATION METER EXCITATION METER P. A. PLATE P. A. PLATE MODULATOR PLATE MODULATOR PLATE DOUBLER PLATE INT. AMP. GRID INT. AMP. PLATE P. A. GRID P. A. GRID 115 volts 5.0 volts 35 ma 2 ma 150 ma 75-100 ma 65- 80 ma 250 ma 290 ma 40 ma 200 ma 320 watts 500 watts 125 volts 5.3 volts 8 ma 175 ma 260 ma 300 ma 50 ma 105 volts 4.9 volts 25 ma 1 ma 60 ma 50 ma 200 ma 200 ma 35 ma 210 watts 325 watts
Table XI. Characteristics of vacuum tubes
Signal Corps Tube VT-46A VT-80 VT-94 VT-95 VT-100 VT-103 VT-107 VT—115 VT-139 VT—145 VT—218 VT-220 VT-231 VT-233
JAN type 866A/866 80 6J5 2A3 807 . 6SQ7 6V6 6L6 OD3/ VR-150 5Z3 100-TH 250-TH • 6SN-7GT 6SR7
Description Mercury vapor half-wave rectifier High vacuum full-wave rectifier Triode Triode Beam power Duplex diode triode Beam power Beam power Voltage regulator High vacuum full-wave rectifier Triode Triode Twin triode Duplex - diode triode
A-c filament voltage A-c filament current (amp) D-c plate voltage D-c screen voltage D-c grid-bias voltage Max a-c voltage per plate Max inverse peak voltage D-c plate current (ma) D-c screen current (ma) D-c grid current (ma) Max d-c output current (ma) Plate dissipation (watts) Approx grid driving power (watts) Approx output power (watts) Plate resistance (ohms) Transconductance (microohms) Amplification factor Load resistance (ohms) 2.5 5.0 10,000 250 5.0 2.0 400 1,400 110 6.3 0.3 250 -8.0 -9.0 7,700 2,600 20 2.5 2.5 300 -62 40 15 800 5,250 4.2 3,000 6.3 0.9 600 250 -50 100 9.0 3.0 25 0.22 37.5 6.3 0.3 250 -2.0 0.8 91,000 1,100 100 6.3 0.45 300 150 -25 35 5 3.0 12 6.3 0.9 375 200 -35 88 9 3.5 20 0.18 17 f 150 30 5.0 3.0 500 1,400 250 5.0 6.5 2,000 225 100 380 30 16,000 5.0 10.5 2,500 -220 290 70 250 42 600 32 6.3 0.6 250 -8.0 9.0 7,700 2,600 20 6.3 0.3 250 -9.0 9.5 0.3 8,500 1,900 16 10,000
195
j--------------- 83 *------------4
WEIGHT = 4300 LB LOADED TLI645I
Figure 136. Shelter H0-17-A—dimensional outline sketch.
196
1 ! [1 I'
M J. • . =■ s
I I
4-.- ■ H— !► ; _
■* l£------------— 55^’----------- . r
“’4
h---------------------------------J L---,4---j
WEIGHT = I65 LB LOADED TLI6457
Figut e 137. Chest CH—88—A—dimensional outline sketch.
197
J/,s
CHEST CH-88-A
LAYOUT OF CONTENTS
y y y y y y y y
COIL UNIT C-387-3 COIL UNIT C-388-A COIL UNIT C-389-A COIL UNIT C-39O-A COIL UNIT C-447 COIL UNIT C-448 COIL UNIT C-449 CAPACITOR C2g 2.0-3.5 MC. 3.5-45 MC. 4 5-57MC 5.7-8 MC. 8-11 MC, 11-14 MC. 14-18 MC. OR C30
QUANTITY 2 QUANTITY 2 QUANTITY 2 QUANTITY 2 QUANTITY 2 QUANTITY 2 QUANTITY 2 kammc
□ U M fwr
QUANTITY 2
~y y y y y y y y
TU-47 TU-47 TU-51 TU-51 - MICROPHONE T-50 CAPACITOR C2g
RELAY RY, °UANT'TY ' ,2MMF
1 CARTON QUANTITY I
—i------------1------------1------------t---------- PLATE POWER SPARE FUSES SPARE
V V y QUANT)TY ( QUANTITY I PILOT LAMPS
TU-48 TU-48 TU-52 TU-52
~y y y y ~y y y y
TU-49 TU-49 TU-53 TU-53 TU-47 TU-49 TU-51 TU-53
y y ~y y y y ~y ~y
TU-50 TU-50 TU-54 TU-54 TU-48 TU-50 TU-52 TU-54
----—----------—-------------------------------------11 “---------------------------------------------------
TLI6462
Figure 138. Chest CH-88-A—lay-out of contents.
198
ll*"' --II ■■ ~ "..[ "1BI-'*- - \ r-T-^s— ~ay —•err-' ~ ~ I - r " * - I -■ J ■ —
o o ~© o © © ^r~~ ° ° )
------—.—---------------------------CJ_.—“ ... ----------xU":— ^"1.
-|vp into
v 2
I |____________________________________________________________________________________________________[I ____________ . ; ♦ ..."~'j"
L________________________________________________________.78±-l_________________________________________J k-6i-4-------6j-|‘
F* 78 2 C-C MTG HOLES “ C-C MTG HOLES 8 1
-------------------------------------------------------eo‘------------------------------------------------
I " ---------18 ±.--------
WEIGHT--300 LB LOADED TLI6458
Figure 139. Chest CH—89—A—dimensional outline
199
____________________________________________________________________________________I ______________________________________________________________________________________
CHEST CH-89-A CONTENTS CHART
HINGE______________ HINGE HINGE HINGE
A HYDROMETER ~ 25/
VT-22O VT-2IB VT-218 TUBE Quantity-'|L VT-2I8 2-GROUND STRAPS (B7A2O8) MAST BASE RING FOR MP-47
— FOR SH E LT E R B »■ ■ * utitv ■
SPARES ___________________ 2-GROUND CLAMPS(76BI17) QUANTITY- I
r OR |4 J FOR TRUCK BODY co
OUANTITY-I QUANTITY-1 QUANTITY-1 SPEECH AMP > CA«BON QUANTITY-1 CAPACITOR T MAST BASE SPR.NG
AND TETRA - CH LORIDE Q.q C?X
RADIO TRANS. QUANTITY-1 jMFp 4Q00V 1 ASSEMBLY FOR MP-47
, ) - 1 „ 1 —t-------------------,---—---- quantity-ieach §
-J y y 'y CAPACITOR ____________________ “■ CORD CO-314
5 Clft C17 2'-7 . CORD CO-316
= OPERATING OPERATING OPERATING n a - a a MFn nnnv 5
« u 85 8-5MFO IOOOV SPARE ANALYZER BC-IO52-E ® «
- SPARES SPARES SPARES QUANTITY-1 QUANTITY-1 J QUANTITY - I EACH g
° CARTON I CARTON 2 CARTON 3 --------- REC ANTENNA FOR TRANS 2 « J f
© X-,,, .taoo GUY ASSEM8LV L *“ ? STAKE ASSEMBLY GP’B °
“ INSULATORS, QUANTITY-2 STRAP ST-I9-A P z P-5 OU4NTITY-2 K
“• ___________ GASKETS AND 3 SI IS A £ u. 5 OUANTHY 2 <
T7 f) ~7) BUSHING 777 H---------- QUANTITY-3 J o a. g uj £
FOR MP-47 S REC ANTENNA -S © £ 5 - IOO FT ANT WIRE
TROUBLE GUY ASSEMBLY " 1 , o UJ r> 1
LAMP SMALL TCOLS SPARE 77}-------------------- OUANTITY-2 MAST BASE ^COUNTERPOISE CP-I5-B " 2 ? « j >
WITH AND LAMP ._________________ BRACKET „„„„ „„ r °: Q
= s_ = r W
lli Io T I (a) • i
1 i i A i
. T) , AT I L-ZZl WEIGHT = 87.5 LB LOADED TLI6460
Figure Hl. Chest CH—10&-A—dimensional outline sketch.
’ 201
, BOX BX-34-B QUAN.2 IIO V TROUBLE LAMPS SPARE TUBES FOR TRANS. |7 TOOL BOX TE-48
^7
47 FREQUENCY METER SCR-2II
TYPEWRITER
VT-22O QUAN.2 VT-218 QUAN. 2 VT-218 QUAN, MISC.TRANS.TUBE MISC. TRANS. TUBES
TLI6464
Figure llj.3. Chest CH-119—( )—lay-out of contents.
Is <» » a s I J1
| si a a a /Of XX/ld.
TO /7 (Next superior headquarters) (Station) (Technical service)
cOMPLlETEMAJ^^ITEM ~ ~
NOM FNOATlfRF “ XXfy
73g ~ a=> / o — E Xy
MODEL MANUFACTURER -
e xxx XX^yo^A-
U. S. A. REG. NO. SERIAL NO. 7/ DATE RECEIVED ~if
£Xde^ ~X. /4153-XXjd -4-5'0/ GZ8 2 XXa 44
EQUIPMENT WITH WHICH USED (if applicable) :: ~.
(Xyccdd XXt SO.E' -399- C ) XX^ /-/O-//_________________________________________________________________________
NOMENCLATURE OF DEFECTIVE COMPONENT
DART NO. - TYPE
3D68-34 C Jo) /vy'jLdtf 6 a*/f - /o + fojb, GGou.d.Q.
MANUFACTURER “ " " U * ~~9 DATE INSTALLED
____________________________/4 XXr 44
V * LENGTH OP SERVICE
DATE OF INITIAL TROUBLE TOTAL PERIOD OF OPERATION BEFORE FAILURE (FILL IN WHERE APPLICABLE)’
7ZO X'-Jr 44 Y E A RS MONTHS DAYS HOURS MILES ROUNDS
TOTAL YEARS MONTHS DAYS
TIME z*) A C ~ - - -
INSTALLED L> O Co
DESCRIPTION OF TROUBLE AND PROBABLE CAUSE
GIVE TYPE OF FAILURE. MECHANICAL. ELECTRICAL. WORKMANSHIP. MATERIAL. DESIGN
C JO Xld-Ze/CE Cred/ i^ 44
RECOMMENDATIONS * ' f (/ /Y * ——£/ {.
___________ ft- isXnd.
OFFICE STATION DATE SIGNATURE ~
______________________________________________
(Technical service) NAME
TO CHIEF /9.C EL A. Wt L SO74
NAME f V f ‘ RANK AND TITLE /J
Ca&tr.j C.
STATION ijanK ORGANIZATION
______________________________________________________________________________________S7± dLl ■ &
INSTRUCTIONS___________________________________________________________ft '
1 • h *s imperative that the Chief of Technical Service concerned be advised 5. It will not be practicable or desirable in all cases to fill all blank spaces
at the earliest practical moment of any constructional, design, or operational of the report. However, the report should be as complete as possible in order
defect in materiel. This form is designed to facilitate such reports and to provide to expedite necessary corrective action. Additional peHirent information not
a uniform method of submitting the required data. provided for in the blank spaces should be submitted as inclosures to the form.
2. This form will be used for reporting manufacturing, design or operational Photographs, sketches or other illustrative material are highly desirable.
defects in materiel with a view to improving and correcting such defects, and for 6.. When cases arise where it is necessary to communicate with a chief cf
use in recommending modifications of materiel. ' service in order to assure safety to personnel, more expeditious means of coir.-
3. This form wiU not be used for reporting failures, isolated material defects or L„U“Cah°n QWauthor“ed- This fom be u6ed to confiTm madi
malfunctions of materiel resulting from fair-wear-and-tear or accidental damage e^e o.Y8, meailj' . . . ,. j f
nor for the replacement, repair, or the issue of parts and equipment. It does not 7J T?1S f,or” m°de °a‘ U81n? V =?nnc.S ONJamzations and forward^,
replace currently authorized operational or performance records “ duplicate through command channels to the cmef of technical service Tho
. j office of the chief of technical service receiving the report will forward an iniorma-
4. neports ot malfunctions and accidents involving ammunition will continue tion copy to the Commanding General, Army Ground Forces or Army Air F jees,
N ' as directed in the manner described in AR 750-10 (Change whichever is applicable, and to the Commanding General, Army Service lorces.
5?r‘ 8- Necessity for usinw this form will be determined by the using or service troops.
W. D., A. O. O. Form No. 468
1 December 1943 16-37786-1 u. s. covebnuemt raixTmeorrics
TLI534O
Figure 151. WD AGO Form f68.
COLOR SIGNIFICANT FIGURE MULTIPLIER VOLTAGE RATING (VOLTS) CHARACTERISTIC (AWS MICADIELECTRIC)
RMA MICA- AND CERAMIC-DIELECTRIC AWS MICA- AND PAPER-DIELECTRIC AWS CERAMICDIELECTRIC
BLACK 0 1 1 A
BROWN 1 10 10 100 B
RED 2 100 100 200 C
ORANGE 3 1000 1000 300 D
YELLOW 4 10,000 400 E
GREEN 5 100,000 500 F
BLUE 6 1,000,000 600 G
VIOLET 7 10,000,000 700
GRAY 8 100,000,000 0.01 800
WHITE 9 1,000,000,000 0 1 900
GOLD 0 1 1000
SILVER 0.01 2000
NO COLOR 500 TLI34I7-I
Figure 152. Capacitor color codes.
207
RMA 6-DOT COLOR CODE FOR MICA-DIELECTRIC CAPACITORS
-H~ p SIGNIFICANT FIGURES
S W FIRST SECOND THIRD
1 CAPACnun I rW-ft
| MiQRcifej
V?ALIiNrE CAPACITANCE MULTIPLIER RATING TOLERANCE
RMA 3-DOT COLOR CODE FOR AWS 6-DOT COLOR CODE FOR
MICA-DIELtCTRIC CAPACITORS PAPER-DIELECTRIC CAPACITORS
ARE ALWAYS SIGNIFICANT FIGURES
wnc mlvvmio piper SECOND
SIGNIFICANT FIGURES SILVER a , 1 /
FIRST SECOND J\ 2 /
______fW /
9 9 9 = \ =
T-T toito
\ OPERATING '
MULTIPLIER TEMPERATURE MULTIPLIER
MULTIPLIER RANGE
The silver dots serve to identify this marking. The ___________.__________________ sixth dot shows whether the capacitor has a maxi-
Capacitors marked with this code have a voltage mum operating temperature of 167°F (black) or rating of 500 volts. 185°F (brown)
CAPACITANCE TOLERANCE TEMPERATURE COEFFICIENT OF CAPACITANCE xlO’6 mmf/mmf/°c
RMA & AWS MICA-AND PAPERDIELECTRIC (PERCENT) RMA CERAMICDIELECTRIC (PERCENT) AWS CERAMICDIELECTRIC GREATER THAN 10 MMF (PERCENT) AWS CERAMICDIELECTRIC LESS THAN 10 MMF (MMF)
20 20 20 2.0 0
1 1 1 - 30
2 2 2 — 80
3 3 2.5 0.25 -150
4 4 -220
5 5 5 0.5 -330
6 6 -470
7 7 -750
8 2.5 4- 30
9 10 10 1.0 Not specified
5
10
20 TLI347-2
Figure 153. Capacitor color codes.
208
AWS 6-DOT COLOR CODE FOR AWS COLOR CODE FOR TUBULAR
MICA-DIELECTRIC CAPACITORS CERAMIC-DIELECTRIC CAPACITORS
J™ significant figures significant figures
blaVk first second first second
DLAU\
=1111 Ik—1= q o> q timix *
P O Q c™EUntE ToZnce"
characteristic capacitance multiplier OQOu ‘
TOLERANCE Ljy---______________
The black dot serves to identify the AWS marking. ciI^Vakit5
Capacitors marked with this code are rated at 500 SIGNIFICANT FIGURES
volts, except the following AWS type CM35 capaci- -----——_________________________________
tors with capacitances of 6,800, 7,500, and 8.200 Capacitors marked with this code have a voltage micromicrofarads, and AWS type CM40 capacitors rating of 500 volts, with capacitances of 9,100 and 10,000 micromicrofarads are rated at 300 volts.
RMA COLOR CODE FOR TUBULAR
CERAMIC-DIELECTRIC CAPACITORS
-----------------------------------------------------------------------------------
I I
► RMA: Radio Manufacturers Association < CAPACITANCE SIGNIFICANT FIGURES
> aia/c a ■ j < TOLERANCE FIRST SECOND THIRD
J AWS: American War Standard < \ \ I
> (American Standards Association] < \ \ | S
i--------------------------------------I =—C' BlHwBll—
> NOTE: These color codes give all capacit- | r Kvl Lvw J
> ances in micromicrofarads. 1 /
► < TEMPERATURE mii.tidiicd
L______________________________________COEFFICIENT MULTIPLIER
Capacitors marked with this code have a voltage rating of 500 volts.
209
[*rkSoR I
H a a n F O AWS COLOR CODE F0R
5 11 II 11 » FIXED COMPOSITION RESISTORS
FIXED COMPOSITION RESISTORS tolerance multiplier significant figures’
_____________________________________ \ ( FIRST SECOND
\ , j / .......... /
SIGNIFICANT FIGURES V7/,T
FIRST (BODY) SECOND (TIP O O O'
EImA “-------------------------------------------------T
significant figures | [| FIRST SECOND
U MULTIPLIER U \,. / ~...
=1 | 11 u=
reii------------- iOLMlJ____________'
=> / \
V& Y/^Y/X MULTIPLIER TOLERANCE
FIRST ^COND^^-ANCE
SIGNIFICANT FIGURES MULTIPLIER --------—---------.------------
The exterior body color of insulated resistors may ______________________________________be any color except black. The usual color is natural
Insulated fixed composition resistors with axial tan. The exterior body color of uninsulated resistors leads are designated by a natural tan background with axial leads may be either black or white. The
color Non-insulated fixed composition resistors with exterior body color of uninsulated resistors with
axial leads are designated by a black background radial leads may be black or it may be the color pf
color the first significant figure of the resistance value.
SIGNIFICANT TOLERANCE
COLOR FIGURE MULTIPLIER (PERCENT)
BLACK 0 1
BROWN 1 10
RED 2 100
ORANGE 3 1000
YELLOW 4 10,000
GREEN 5 100,000 ► j
> 4
BLUE 6 1,000,000► RMA: Radio Manufacturers Association j
VIOLET 7 10,000,000, AWS American War Standard 4
GRAY 8 100 000 000 > (American Standards Association) <
_________________________' '____________________________> 4
WHITE 9 1,000,000,000 ► <
GOLD 0 1 5
SILVER 0.01 10
NO COLOR 20
———J____________________ - n !34I8
Figure 157. Resistor color codes.
210
\ ANT LfAD \ amt LEAD ,
fjTTlNGASS'V X. riTTlNG ASS’Y
’ pV MP-4 8j2^- MAIN REC ANT LEAD____________________'
\ Ujj aJm rec ant leap \ _________kt_________| (__i__________________________— — —S— — -’- — — — ?L62_____________________________-
\ kT \ FT SPEECH AMPLIFIER | LAMP |------- ' J
-30->X *® __________ mP-5O-a\ *» । BC~6i4~E * |
’ ’ _ TQ8C-4IO TO J8-7O £ SPEAKER ____ _____PLUG TiP, WHITE——.
,__r4a^E_sLcHZi2i_-L±aux_operatin_gL (-------------------------LQJ Q HZfD O X ° °^==3-----,u«eve..uU~
I 1 LAMP | I | SO,05 SO,0? ’ MM
- " SPEAKER ! r—PLUG TiP, WHITE—, I I £ U—J ,
7 LS-3 O o=c:zi.)—I--T I.’ I I I I r I < I
I O ■— PLUG SLEEVE .BLACK J | I n * ♦ o 4> h « ----------
• ® • I “ » r k j * °
1 P I Q 1
’ *■ I IX I «©-'< - ° u, w________________________MAIN AUDIO CORO CX-I43/MP3-?__ ’
! -------- I- s~ i » > » * “ * z I ; ZZZZZZZZZZZZZZZZZZ I
I LL I H I 'J b I rh-------------------------’ “H-sarr
r'i n ............................................-Z nTrrmhiHI flo q 1 ral
I—J । L-PLUG SLEEVE. BLACK—' o J « * • * * * “ “ J J ----------------IP TELEPHONE ।
! I k ' '
t - Q । । wZ7.’?*'«°ot-txxx (“I IJ l 2 |
—— — ———— — — —— — — — — ——_— j I u ° T PLUS rip, WHITE . r^LACP—C ’
| | « « I 1 |_L J L. |
I «TARM------1 >{T CQRQ__________|—PLUA TIP, WHITE --■ I 1 I 1 I 1 I 1 I 1 1 I _______ V L-PLUS SLEEVE.BLACK-I L«,H,TE-O|
........................................ i I rW 111 rni Fri^oo ।-----------------------------------------। -BLUE,.—............................,OEOO « 3 ‘ IO " I* S/-\ rm T'l (—O-OO-O. 'LAO , p»p-| , ---------
____________________________________CO-355________J-----Til Z\ JUNCTION BOX °O UJ—J L’j CeceWrV-’t'Vuow J L^J
-•wtcw.w— , I , I I J JB-70-A
-.CUE, rrn. v-----U| O n -nJ:
E.xd ffp I ,Lt—jg ... ।
rfp iiH oo
® > • 2 a-2£-J | 80210 _ S°204 ,020S ,020t *°20l ° Q I
1 f h • y । ,□000 0 00 s O | =0—----------------------
Q 5F hH L~a~g~a~6ffl~6~e'i
Q [$• _________T T™
7 |___________CD-563_________________________ -J
--------s--------c.x-]------------------t a m m--------------cj ° antenma
’ j. ' ' I I L_____________________ TUHIMG
-» * F-' r N. " r-ACl UNIT rH
” o 5 > > O u _______T C 1 BLOWER CORD____________ K I
x £ 5 cm oj • . I i I BC-939-A w •»
*” " 7 I C J YELLOW—. ---AC----- H-J nH CONCENTRIC LEAD f J *
LL!_____LU □ -TELLO.- _----- ---- J i O o O 1^----------—J--------------- | 5
| I —WHITE— — I2V-.TERM - L—J L—J £ £
| ] 1 1 p~| _______ ___________RED l|2V*. OPPOSITE GNoJ_। | |
IH H H F R*010 T"**s,"TTe" X
BLOWER | | | p HEATER BC-BIO-C | I
j"! —H I— J --I—L. ___________ ' 3 3 4"l _________ • * s
--4---1___I___I_______il --"eo-- ------*'■•'----- ------m C~} I !~P1 /-s AUX.BATTERY
O O (\ ^rk
--------- - — —---—----1 L—3HIJL0— !— GROUND. B-----J
7/r/T 7?/YrA*ni __QQQ__A nnfl _LOO A w r*
21 i
TUNING CHART OF RADIO TRANSMITTER BC610-E'I f TUNING CHART OF RADIO TRANSMITTER BC-610-E
for for
Tuning Unit TU-47 Tuning Unit TU-48
NOTE Ule v C 50 Frequency Range 2.0-2.5 M C Frequency Range 2.5-3 2 M C
On 2-2.5 MC
APPROXIMATE DIAL SETTINGS APPROXIMATE DIAL SETTINGS
* Tuurur rnuToni c ANTENNA TUNING nnrn.nur rnvrT.> TIIMtur fONTOni 9 ANTENNA TUNING
OPERATING CRYSTAL TUKIHG CONTROLS UH|1 3(.?39.A OPERATING CRYSTAL TUNING CONTROLS 0f.939.A
FREQUENCY FREQUENCY <011 ---- ------—----------• FREQUENCY FREQUENCY COIL ---- (? .-------------
IM IF INI TuM.lr BflM0 IM IF UNIT INT riLiLr BAND
KILOCYCLES USED *° D0US X T G SWITCH ^P11"6 L0A0IMG KILOCYCLES USED *0 DOUB ' TUHIMG SWITCH COUPLING LOADING
POSITION ____ I — POSITION
2000 2000 O387 D ]] 2.4 4.7 20 2-10 4.9 4.6 2500 2500 C'387 D 10 07 2 8 7 210 43 226
2550 2550 O387 D 18 1.7 3.4 12.5 2 10 4.3 23.9
2050 2050 C-387-D 22 3.2 5.2 3 0 2-10 4.9 7.1 2600 26fl0 c.3g7.D 26 ? Jfl 4 3 25Q
2100 2100 C 387 D 32 3.8 5.5 3 9 2-10 5.1 9.4 2650 2650 C 387 D 33 3.1 4.4 21.5 2 10 4.2 26.2
r„ 2700 2700 C 387 D 40 3.7 4.9 25.5 210 4.2 27.3
2150 2150 C387-D 41 4.3 5.9 47.5 2-10 4.9 11.4
2750 2750 0387-D 46 4.1 5.3 29.0 210 4.2 28.3
2200 2230 03870 49 4.8 6.3 56.5 2-10 4.8 13.3 2800 2800 C.337-D 52 45 5 g 33q 210 4.2 29.3
2250 2250 0387 D 57 5.2 6.7 6 3.5 210 4 .7 1 5.1 2850 2850 O387 D 58 4.9 6.1 365 210 4.2 30.2
290S 2900 C-387 D 63 5.2 6.5 405 210 4.5 31.0
2300 2300 C 387 D 63 5.6 7.0 70 2-10 4.6 16.8
2950 2950 O387 D 68 5.6 6.8 435 210 4.1 32.0
2350 2350 0387-0 69 6.0 7.4 77 2-10 4.5 18.3 3^ 3000 C387-D 73 5.9 7.2 4 7 0 2 10 4.1 32.7
2400 2400 C 387 D 75 6.3 7.7 83 2-10 4.5 19.8 3050 3050 0387-0 78 6.1 7.4 50.0 2 10 4.1 33.5
3150 31G0 C-387-D 82 6.4 7.7 53.0 210 4.1 34.2
2450 2450 0387 0 81 6.7 8.0 88 2-10 4.6 21.3
3150 3150 03870 87 6.6 7.9 55.5 210 4 2 35.0
2500 2500 C387-D 85 [ 7.0 8.2 94 | 2-10 4.6 22.6 3200 3200 0387-0 90 6.8 8.0 58.5 210 4.2 35.6
HOTI-FOO EXACT M.O. SETTUI5, USE FREQUENCY METER SET SCR-211-() MOTE-FOR EXACT M.O. SETTING, USE FREQUENCY METER SET SCR-211-()
PART HO. 9M1QS J ___________________________________PART WO. 92B105_
NOTE: VIEW ABOVE SHOWS BOTH FACES OF CHART. FACES COMBINE BACK TO BACK TL1668I
TO MAKE ONE CHART.
Figure 156. Timing chart, Tuning Units TU-47 and TU-48.
212
TUNING CHART OF RADIO TRANSMITTER BC-61O-E( TUNING CHART OF RADIO TRANSMITTER BC-610-E
lor for
Tuning Unit TU-49 Tuning Unit TU-5O
Frequency Range 3.2-4.0 MC Frequency Range 4.0-5.0 M C
APPROXIMATE DIAL SETTINGS APPROXIMATE DIAL SETTINGS
OPERATING CRYSTAL TUNING CONTROLS &UNIT K wT OPERATING CRYSTAL TUNING CONTROLS NA ™^G
FREQUENCY FREQUENCY COIL ----- „ —------------- FREQUENCY FREQUENCY COIL ———___________ P 4 _ , B( 939 4_
IN IF UNIT |NT ^ATE BAND IN If UH|T PLATE BAND
KILOCYCLES USED *0 DOUB w HG SWIKH COUPLING LOADING KILOCYCLES USED M.O. D0U8. TUNING SWITCH COUPLING LOADING
_____ POSITION ___ 4MP POSITION 3200_3200 C-387 D 25 3.4 5.8 58.5 210 4.2_35.6_4000 20G0 C 388 C 7 2.2 3.5 48 210 4.0 43 2
3250 3250 C387 D 30 3.8 &.] 61.0 210 4.3 36.3 4^° 2825 C’388 C 13 2 5 3 9 50 210 4 0 43 7
M . 4100 2050 C 388 C 19 2.9 4.3 52 2 10 4.0 44 0
4300 3300 C 387 D 35 4.2 6.3 63.0 2 10 4.3 37.0 4150 2075 C-388 C 24 3.2 4.6 54.5 210 3.9 44 3
3350 3350 C387-D 40 4.6 6.5 65.5 2 10 4.5 3 7.5 4200 2100 03880 29 3.5 5.0 56.5 210 3.9 44 6
3400 3400 C 387 D 45 4.9 6.7 670 210 4.6 38.2 4250 2125 0388 0 34 3.8 5.3 58.5 2 10 3.9 4 4 9
3450 3450 O387 D 50 5.3 6.9 6 9 5 2 10 4.7 38.7 4300 2150 0388 0 39 4.1 5.6 60.5 2 10 4.0 4 5 2
qcnn -Knn r-»fl7-n « c a 7 1 7m Tin c . 4350 2,75 C’388 C 44 4.4 5.9 62.5 2 10 4.0 45.5
3500 3500 0388D 55 56 7.1 21 2-10 3.4 38.9 4400 2200 O388 C 48 4.6 6.1 ' 63.5 2 10 4.0 45.8
3550 3550 C-388C 59 5.9 7.3 235 2~IO 3 5 39.5 4450 2225 0388 0 52 4.8 6.4 65 5 210 4.0 46.1
3600 3600 C-388 C 64 6.1 7.5 265 210 3.5 39.9 4500 2250 0388 0 56 5.1 6.6 67 210 4.0 463
3650 3650 0388 C 68 6.4 7.7 29.5 210 3.6 40.4 4550 2275 C389-C 60 5.3 6 8 155 2-10 2J 46.4
3700 3700 O3S8C 72 6.6 7.9 3 2 210 3.7 4 0.9 ^00 O389 C 64 5.6 7.0 17.5 210 2.9 46.7
4650 2325 0389 c 67 5.8 7.2 20 210 2.9 46.9
3750 3750 0388 C 75 6.8 8.1 35 2-10 3B 41.3 4700 2350 O389 C 71 6.0 7.3 22 210 2.8 47.2
3800 3800 O388 C 79 7.0 8.3 3 7.5 2 10 3.9 41.7 4750 2375 O389 C 74 6.2 7.5 2 4.5 2 10 2.9 4 7.4
3850 3850 C383 C 82 7.2 8.5 40.5 210 3.9 42.2 4800 2400 C 389 C 78 6.4 7.7 2 6.5 2 10 2.9 4 7 6
3900 3900 C-388 C 85 7.4 8.7 4 3 2 10 4.0 42.5 4850 2425 C‘389 c 81 6 6 7 8 29 2 10 2 9 479
4900 2450 C’389 0 84 6.8 8 0 31 2 10 2 9 4 8 1
3950 3950 G388-C 80 7.6 8.8 45 210 4.0 42.9 w0 „„ „ ?|)
4000 4000 C-388-C 91 7.8 8.9 4 8 2 10 4.0 4 3.2 5000 2500 C389C 91 7.1 8.4 355 210 2.8 48.5
NOTE-FOR EXACT M.O. SETTING, USE FREQUENCY METER SET SCR-211-() MOTE-FOR EXACT M O. SETTING, USE FREQUENCY METER SET SCR-211-( )
L— --------------------------------------------- -----------------------------—----------------—J
__________________________PART NO. 92S106 PART NO. 92B106 N0TE:VIEW ABOVE SHOWS B°TH FACES OF CHART. FACES COMBINE BACK TO BACK tL 15950
' O MAKE ONE CHART.
Figure 157. Tuning chart, Tuning Units TU-49 andTU-50.
213
TUNING CHART OF RADIO TRANSMITTER BC-610-E TUNING CHART OF RADIO TRANSMITTER BC-61O-E
f°r for
Tuning Unit TU-51 Tuning Unit TU-52
Frequency Range 5-6 35 MC Frequency Range 6.35-8.0 M C
APPROXIMATE DIAL SETTINGS APPROXIMATE DIAL SETTINGS
ANTENNA TUNING ANTENNA TUNING
OPERATING CRYSTAL TUNING CONTROLS . . UNIT BC-939-A OPERATING CRYSTAL TUMINv CONTROLS BC 939-A
FREQUENCY FREQUENCY COIL ----- !*„ ~ a^n --------- • f'f»Y COIL ------------- 17 -----T" -------
IN IF unit INT PLATE BAND III n UNIT iut BAND
KILOCYCLES USED M °' 00UB AMP TUNI* SW,T(H t0(MI>!G lOflOIW 'KILOCYCLES USED MO. MU» "L IUMIHG SWITCH COUPLING LOADING
’ POSITION ________ POSITION 5000 2500 C389 C 5 2.5 4.0_35 5_210 2.8 48.5_,................... ......
5050 2525 (-389 0 10 2.8 4.3 3 7 5 2 10 2.8 48.7 6350 3175 G390C 8 4.4 2.8 43.5 210 2.3 52.5
5100 2550 C-389 C 15 3.1 4.6 39.5 210 2.8 4&9 6400 3200 0390 0 10 4.6 3.3 45 210 2 2 52.7
5150 2575 C 389C 19 3.4 4.8 41.5 2 10 2 8 49.1
5200 2600 C 389 C 23 3.7 5.1 43 210 2.8 49.3 6500 3250 C390-C 17 5.0 3.8 47.5 2 10 2.2 53.0
5250 2625 C 389 C 27 3 9 5.3 4 5 2 10 2 8 4 9 5 6600 3300 (-39Q-C 23 5 4 4 2 5 0 5 2 10 2 2 53 1
5300 2650 C 389 C 31 4.2 5.6 47 210 2.8 49.6 v jtu u J n.a ju.o z iu t.t jj.i
5350 2675 C 339 C 34 i 4.4 5.8 48.5 2-18 2.8 49.8 6700 3350 C 390 C 29 5.8 4.7 5 3 2 10 2.2 53.4
54CO 2700 C 389 C 38 4.6 6.0 50-5 23 50.0 lAfsQ f-lon-C Al c i rc o Q R
5450 2725 ( 389 C 41 4 8 6.2 52 2-1® 2.8 50.1 - 3408 C 398 C 35 6 1 5J 55 2 10 2 Z 53 6
5500 2750 C-3S9-C 44 5.0 6.4 54 2 IS 2.8 50.4 6900 3450 C’390’C 41 6.4 5.6 53 ' 210 2.2 517
5550 2775 C. 389 C 48 5.2 6.6 5 5-5 2-10 2.8 50.5 tsusw r ann n Al a l l. a *> in no ex n
5600 2800 0389 0 51 5.4 6.7 57 2 10 2.8 5Q7 7000 3508 0390’0 47 6.6 6.0 oC.5 2 10 2.2 54.0
5650 2825 ( 389 C 55 5.5 6.9 58.5 2 18 2.8 50.9 7100 3550 C’390’0 52 6.9 6.4 6 3 2 10 2.2 54.2
5700 2850 (-M9-C 58 5.7 7.1 60 2 10 2.8 51.0 -,„n~ z ,, , , . o r„ „
57Q0 285p 0-3%-c » 5 7 7.1 2-10 2.2 50.9 7200 3600 C’390’C 57 7.1 6.8 6 5 2-10 2.2 54.4
5750 237S- 0’390'0 5.9 7.2 23 2’10 2.2 5L0
5323 2900 C 390-0 64 6.1 7.4 ?5 210 2 3 51.2 7300 3650 C’390’C 62 7.3 7.1 67 210 2.2 54.5
5850 2925 C 390-C 66 6.2 7.5 265 2 10 2.2 51.3 , , , , . nn n nn
5980 2950 ( 395-C 6? 6.4 7.7 28.5 2 10 2.2 51.4 7400 3700 C’390 C 67 7.5 7.4 69 2'10 2.2 54.7
5950 2975 C-390-C 72 6.5 7.8 2*5 2 10 2.3 51.5 7500 375g C390C 7] 77 77 7| 2'10 2.2 54.9
6000 3K9 C353-C 74 6.7 8.0 315 2 19 2.3 51.7 ~ ,,
6050 3025 C 390-C 77 6.8 8.1 33 5 21® 2.3 51.9 76©0 C’390’C 75 7.9 0.9 72.5 2'19 2.2 55.1
3450 79 70 82 « 21S 5,n 77fl® 3850 C390-C 79 8.1 8.2 7 4.5 2*19 2.2 55.2
6150 3075 C39O-C 82 7.1 8.4 365 M 0 2.3 52.0
62^0 3129 C-390-C 84 7.2 8.5 38 5 M® 2.3 52.2 7800 3900 G390C 83 8J 8.4 76 2'13 2.1 55-4
six e£c e n u t!'. ” S 7,M 3,50 87 8'4 “ 7Z5 2"> 2J 555
6350 3175 C399-C 99 7.5 8.9 435 210 2.3 52 5 8000 4000 C'390’C 91 83 8.8 78.5 2'10 2.1 55.7
MOTf-FO« EXACT M.0. SETTWS, USE FREQUENCY METER SET SCR-211-() MOTE - FOR EXACT M.0. SETTIHG, USE FREQUENCY METER SET SCR-2l1-()
___________________________________PART «O 928107 J _________________________________PART NO. 92BI07_j NOTE’ VIEW ABOVE SHOWS BOTH FACES OF CHART. FACES COMBINE BACK TO BACK________________________TLI5948
TO MAKE ONE CHART.
Figure 158. Tuning chart, Tuning Units TU-51 and TU-52.
214
TUNING CHART OF RADIO TRANSMITTER BC-610-E( TUNING CHART OF RADIO TRANSMITTER BC-610-E
for for
Tuning Unit TU-53 Tuning Unj} w.53
Frequency Range 8.0-12.0 MC Frequency Range 8.0-12.0 MC
APPROXIMATE DIAL SETTINGS APPROXIMATE DIAL SETTINGS
OFERATIMG CRYSTAL TUNING CONTROLS AJF|T "r( 939 A OPERATING CRYSTAL TUNING CONTROLS ANTENNA TUNING
IN IF UM|T imt t BAND .r Cull PLATE ramh
usio ■» oou. s«m» touMt m sou, «r _ ,„,t
0W POSITION 8000 4000 £-44743 6 1.5 1.5 20.5 210 1.5 55.5_10,000________5000 £-447.3 61_5.7 5 7' 64 5 10 18 1 1 *2 5
8100 4050 £-447-B| 9 1.8 1.8 2 3 5 2 10 1.5 55.7 10,100 5050 C-447-B 63 5.8 5.8 655 1018 1.1 *2.7
8200 4100 C-447-B 13 2.0 2.0 26. 210 1.5 559 10,200 5100 0447-0 65 6.0 6.0 67 1018 1.1 *3.0
8300 4150 £-447-8 16 2.3 2.3 2 8 5 2 10 1.5 56.1 10,300 5150 £-447-9 67 6.2 6.2 685 1018 1.1 *3.4
8400 42G0 C-447-B 19 2.6 2.6 31 2 10 1 5 56.1 10,400 5200 £-447.9 68 6.3 6 3 70 10-18 1 1 *3 7
8500 4250 C-447-81 23 2.8 2.8 3 3 5 2 10 1.5 56.2 10,500 5250 £-447-B 70 6.4 6.4 71.5 10 18 1 1’ *4’0
8600 4300 £-4476 26 3.1 3.1 36 2 10 1.5 56.4 10,600 5300 C-447-B 72 6.6 6.6 72.5 10-18 1.1 *45
8700 4350 C447 B 29 3.3 3.3 385 270 1.5 56.5 10,700 5350 £-44743 73 6.7 6.7 74 10 18 1.1 *4.7
8300 4400 £-4478 32 3.6 3.6 41 2 10 1.5 56.7 10,800 5400 £-4476 75 6.8 6.8 75 1018 l.l *5.0
8900 4450 C-447B 35 3.8 3.8 43 2 10 1.5 5GB 10,900 5450 £-447B 76 7.0 7.0 76.5 10 18 1.1 *5 3
9000 4500 £-4473 38 4.0 4.0 455 2 10 1.5 57.1 11,000 5500 £-447 6 78 7 1 7 1 77.5 10-18 11 *5 7
9100 4550 £-4478 41 4.2 4.2 47.5 2 10 1.5 57.3 >’.000 5500 C-448-B 78 71 7.1 37 10-18 1.2 *56
«00 4650 C«B 43 4.3 4.3 49.5 2 10 1.5 57 4 II^S C’^ J,9 % 72 3^ I0H8 1.2 .&»
9300 4650 £-4478 46 4.5 4.5 52 2 10 1.5 57.5 11,300 5650 0448-8 82 7.4 7.4 425 1018 12 *65
9400 4700 C447B 49 4.7 4.7 53.5 2 10 t.5 57.7 n,4QQ 5700 £-44^ M 75 |75 445 1(Hg ]2 *67
9500 4750 C-447B 51 4.9 4.9 55.5 2 10 1.5 57.7 11/500 5750 C-448B M 7.6 I 7.6 4s' 10-18 12 *70
9600 4800 C-447S 53 5.1 5.1 57.5 2 10 1.5 57.8 11,603 5800 C448-B 85 7.7 : 7.7 48 1Q-18 1.2 *7 1
9700 4850 C4476 55 5.3 5.3 59 2 10 1.5 58.0 11#700 5850 £-4486 86 78 78 495 ]fl.18 , 2 *74
9800 4900 57 54 54 695 210 1.4 58.3 <11,800 5900 C-4486 87 7.9 7.9 51 10 18 1.2 *7.7
9900 4950 C-447B 59 5.6 5.6 6 3 2-10 1.4 58.4 11 900 5950 C-4486 ga 8n on 52=; in IS 12 *7Q
10,000,1 5000 C-447Bj 61 57 57 J 64.5 2-10 1,4 [58.5 “ 87 87 545 1078 1.2 *8 f
' NOTE - FOR EXACT M.O SETTING, USE FREQUENCY METER SET SCR-211-() MOTE - FOR EXACT M.O. SETTING, USE FREQUENCY METER SET SCR-211-()
• *S«t L.F. loading Coil at 30
» PART NO. 92B1C3 _J ________________PART MO. 9?81®e
NOTE- VIEW ABOVE SHOWS BOTH FACES OF CHART. FACES COMBINE BACK TO SACK Ti 16980
TO MAKE ONE CHART '
Figure 159. Tuning chart, Tuning Unit TU-53.
215
TUNING (HART OF RADIO TRANSMITTER BC-61O-E U TUNING CHART OF RADIO TRANSMITTER BC-610-E
for for
Tuning Unit TU-54 Tuning Unit TU-54
Frequency Range 12-18 MC Frequency Range 12-18 MC
APPROXIMATE DIAL SETTINGS APPROXIMATE DIAL SETTINGS
OPERATING CRYSTAL TUNING CONTROLS o«"!G OPERATING CRYSTAL TUNING CONTROLS AuLEn *BC 939'flG
FREQUENCY FREQUENCY (OIL ---- f ‘ ---“"'J-K-W/- FREQUENCY FREQUENCY COIL _____________ Lrf --- । ----
IN IE UNIT imt *AND IN IF UM|T |MT BAND
KILOCYCLES USED M 0 DOUB *„ IUN,MG $W|TCH COUPLING LOADING KILOCYCLES USED *0 DOM SWIICH COUPLING LOADING
__________________________AMP_____POSITION________________________________________________POSITION______
14,000 3500 C-449B 46 3.2 4.6 37.5 10-18 |.| »l2.0
12,000 3000 C-4486 6 .3 1.1 54.5 10-18 1.2 *8.1 14,200 3550 C-4496 49 3.4 4.8 40.5 10*18 1.1 *12.3
12,100 3025 C-4486 9 .4 1.4 55.5 10-18 1.2 * 8.4 14,400 3600 04496 52 3.6 5.1 43 10*18 l.l *12.4
12,200 3050 04486 12 .6 1.6 57 10-18 1 I *8.6 14,600 3650 C449B 55 3.8 5.3 46 10*18 I I *126
12,300 3075 C-4486 14 .8 1.8 5 85 10-18 1.1 *8.8 14,800 3700 C-449-B 58 3.9 5.5 48.5 10*18 I I *13.0
12,400 3100 04486 17 1.0 2.1 60 10-18 1.1 *9.0 15,000 3750 04496 61 4.1 5.7 52.5 10 18 I I *13.2
12,500 - 3125 C-448-B 19 1.2 2.3 61 10-18 1.1 *9.2 15 200 3800 04496 63 4.3 5.8 545 10-18 l.l *13 6
12,600 3150 04486 21 1.4 2.5 625 10-18 1.1 *9.5 15,400 3850 C449.J 65 45 6 1 57 10 18 । 0 *138
J^an o! 15 8 15,600 3900 C’449B 68 4 7 6 2 59 1018 10 *142
S ™ Z : 66.5 10-18 H :.oo ™ ™ « - 615 r 10 ■"■2
3250 C-4-M 29 1.9 3.2 67.5 10-18 13 iS°“ 4000 72 5 ° 66 63 ,H8 10 ?44
13,100 3275 C-4486 31 2.1 3.3 69 10-18 l.l *10.4 , 6'200 4050 C449’B| 74 57 67 65 1018 10 146
13,200 3300 0448-B 33 2.2 3.5 70 10-18 1 I *10.7 16'400 4100 C'449B 76 5 3 68 67 1018 09 ’,47
13,300 3325 C-4486 35 2.4 3.7 71 10-18 l.l *10.8 16,600 4150 C449‘B 78 55 69 69 10‘18 09 *147
13,400 3350 C-448-B 37 2.5 3.8 72 10-18 l.l *11.0 16,800 4200 C-4496 80 5.6 7.1 71 10 18 0.8 *14.9
13,500 3375 C*4486 38 2.6 4.0 73 10*18 l.l *11.2 17,000 4250 C-4496 82 5.7 7.2 73 10*18 0.8 *15.1
13,600 3400 C-4486 40 2.7 4.1 745 10-18 l.l *11.3 17,200 4300 C-4496 84 5.8 7.4 7 5 10*18 0.8 ‘15.4
13,700 3425 04486 41 2.8 4.3 7 5 10-18 l.l *116 17,400 4350 04496 E5 5.9 7.5 76.5 10*18 0.7 ’154
13,800 3450 04486 43 3.0 4.4 76.5 10-18 l.l *11.6 17,600 4400 04496 87 6.1 7.7 7 7 10 18 0.5 *156
13,900 3475 04486 45 3.1 4.5 7 7 10-18 1.0 *11.8 17,800 4450 04496 89 6.2 7.9 80 10*18 0.4 *16.0
14,000 3500 C-448 6 46 3.2 4.6 7 8 10-18 1.0 *119 18 000 45Q0 (-4496 91 6.3 8.1 82 10*18 0.4 *163
MOTE—FOR EXACT M.O. SETTING, USE FREQUENCY METER SET SCR-211-() MOTE —FOR EXACT M.O. SETTING, USE FREQUENCY METER SET SCR-211-( )
_____’5ft 1 F lood'n9 Co11 °’ 30_-Set I F Loading Coil at 30 ____________ __________________________________PART NO. 9?BW9_PART NO. 92B109 NOTE- VIEW ABOVE SHOWS BOTH FACES OF CHART. FACES COMBINE BACK TO BACK______________________TLI5949
TO MAKE ONE CHART.
Figure 160. Tuning chart, Tuning Unit TU-54.
UNT LIBRARIES DENTON TX 76203
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