    [Carrier Terminal Oa-13/Fc, Carrier Repeater Oa-10/Fc, and Carrier Filter F-36/Fc (Type H Carrier Telephone Packaged Equipment)]
    [From the U.S. Government Publishing Office, www.gpo.gov]

    ﻿NON-CIRCULATING
    CARRIER TERMINAL OA-13/FC, CARRIER REPEATER OA-IO/FC, AND CARRIER FILTER F-36/FC
    (TYPE H CARRIER TELEPHONE PACKAGED EQUIPMENT)
    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distributed solely for the use of the military, naval, and civilian personnel of the War and Navy Departments, and may not be published or reproduced in whole or in part, or in any manner or form (except by lawful copyright holders who may reproduce their copyrighted material in its original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.
    WAR DEPARTMENT
    MAY 1945
    Document	C | F~\ /"“ / /	Z'—A	I
    Reserve	\ / | | LT) | P LT) 1 I '
    TOj
    WAR DEPARTMENT TECHNICAL MANUAL
    WAR DEPARTMENT TECHNICAL MANUAL
    T M 1 1 - 2 0 2 5
    CARRIER TERMINAL OA-13/FC,
    CARRIER REPEATER OA-IO/FC, AND CARRIER FILTER F-36/FC
    (TYPE H CARRIER TELEPHONE PACKAGED EQUIPMENT)
    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distributed solely for the use of the military, naval, and civilian personnel of the War and Navy Departments, and may not be published or reproduced in whole or in part, or in anj' manner or form (except by lawful copyright holders who may reproduce their copyrighted material in its original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.
    WAR DEPARTMENT
    MAY 19 4 5
    United States Government Printing Office
    Washington : 1945
    WAR DEPARTMENT
    Washington 25, D. C., 31 May 1945
    TM 11-2025, Carrier Terminal OA-13/FC, Carrier Repeater OA-IO/FC, and Carrier Filter F-36/FC (Type H Carrier Telephone Packaged Equipment), is published for the information and guidance of all concerned.
    [AG 300.7 (26 Apr 45)]
    By order of the Secretary of War :
    Official :	G. C. MARSHALL
    J. A. ULIO	Chief °f Staff
    Major General
    The Adjutant General
    Distribution :
    AAF (2) ; AGF (2) ; ASF (2) ; T of Opn (2) ; Dept (2) ; Def Comd (2) ; Arm & Sv Bd (1) ; S Div ASF (1) ; Tech Sv (2) ; SvC (2) ; PE (2) ; Gen Oversea SOS Dep (Sig Sec) (2) ; Dep 11 (2) ; Gen & Sp Sv Sch (2) ; USMA (10) ; WDGS Lib (5) ; Lab 11 (2) ; A (2) ; Three (3) copies to each of the following T/O & E: 11-107; 11-127; 11-500, (GN), (GO), (GP), (GQ) ; 11-587; 11-592; 11-597.
    Refer to FM 21-6 for explanation of distribution formula.
    ii
    CONTENTS
    PART ONE.
    Section I.
    II.
    III.
    PART TWO.
    Section IV.
    V.
    VI.
    VII.
    VIII.
    PART THREE.
    Section IX.
    X.
    XI.
    XII.
    PART FOUR.
    PART FIVE.
    Section XIII.
    XIV.
    XV.
    XVI.
    APPENDIX I.
    II.
    III.
    INDEX........
    INTRODUCTION.	Paragraphs
    Description .................................................................... 1-7
    Application ................................................................... 8-24
    Unpacking, setting up, and repacking.......................................... 25-28
    OPERATING INSTRUCTIONS.
    Equipment connections and preliminary	adjustments...........................   29-42
    Detailed tests, adjustments, and system	line-up............................... 43-56
    Routine checks of performance................................................. 57-59
    Operation under unusual conditions............................................ 60-62
    Summary of procedure for placing equipment in service............................ 63
    PREVENTIVE MAINTENANCE.
    Preventive maintenance techniques............................................  64-67
    Preventive maintenance check list................................................ 68
    Lubrication ...................................................................   69
    Moistureproofing and fungiproofing............................................ 70-74
    AUXILIARY EQUIPMENT (NOT USED)
    REPAIR INSTRUCTIONS.
    General	repair procedure..................................................    75-76
    Detailed	functioning	of	equipment............................................ 77-90
    Trouble	location..........................................................   91-107
    Repairs	.................................................................   108-111
    LIST OF COMPONENT PARTS............................................
    MAINTENANCE PARTS..................................................
    REFERENCES ........................................................
    Page
    1
    12
    28
    34
    60
    71
    74
    75
    76
    79
    80
    80
    91
    93
    110
    125
    128
    129
    130
    133
    iii
    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—Panels, switches, controls, vacuum tubes, terminal strips.
    2.	Cut—Cables, cords, all wiring.
    3.	Burn—Resistors, capacitors, coils, technical manuals, equipment drawings.
    4.	Bend—Mounting plates.
    5.	Bury or scatter—All of the above pieces after destroying their usefulness.
    DESTROY EVERYTHING
    SAFETY NOTICE
    Voltages used in this equipment are high enough to endanger life and may be fatal if contacted by operating personnel. Attendants must be careful not to contact high-voltage plate circuits and the a-c input connections. Do all testing with insulated test leads. Disconnect a-c powercord when making adjustments and when disassembling any part of the equipment.
    v

    —
    Figure 1. Typical installation of type H carrier telephone packaged equipment.
    TL5O5I2'S
    —____
    —~"~™--———~
    —

    This manual supersedes TM 11-2025, Type H Carrier Telephone Packaged Equipment, 30 June 1944, and TM 11-2038, Installation Instructions for lype H Carrier Telephone Packaged Equipment, 30 June 1944.
    PART ONE
    INTRODUCTION
    Section I. DESCRIPTION
    I.	General
    a.	Carrier Terminal OA-13/FC (Western Electric type H carrier terminal panel X-66217A), Carrier Repeater OA-IO/FC (Western Electric type H carrier repeater panel X-66217B), and Carrier Filter F-36/FC (Western Electric type H carrier line panel X-66217C) are used to form a carrier system which is generally known as type H. Type H carrier telephone packaged equipment (fig. 1) provides means for superposing one additional telephone channel on an existing open-wire voice-frequency circuit, or two additional telephone channels on a radio circuit. The type H carrier channel may be used for a voice-frequency telegraph system within certain limitations. The equipment consists of three panels designated H CARR TERM, H CARR REP, and H CARR LINE. The equipment is mounted on panels, suitable for installation in apparatus cabinets or on standard 19-inch relay racks which must be provided separately. Equipment for protection against excessive line voltages must also be provided separately.
    (1)	A complete carrier terminal requires one carrier terminal panel and one carrier line panel. The carrier terminal panel may be used either as an East or a West1 terminal, and may be terminated on the switchboard side either on a two-wire or a four-wire basis. Terminal panels may also be used at each end of a radio link to permit operation of one or two carrier telephone channels in addition to the regular radio talking channel. Voice-frequency ringing equipment must be provided separately for signaling over the H carrier system.
    1 The ends of wire circuits and the associated equipment are generally designated East and West, depending upon their geographical location or local agreement. For lines running North and South, the ends are usually designated East and West respectively.
    (2)	A complete carrier repeater requires one carrier repeater panel and two carrier line panels.
    (3)	Where it is desired to transfer the carrier circuit without being repeatered, two line panels are used in tandem.
    b.	The arrangement for superposing a type El carrier system on an open-wire pair is shown in figure 2, which also shows the application of terminal and line panels. As illustrated, two telephone channels are provided, one voice-frequency circuit and one carrier circuit.
    c.	No equalization or automatic regulation of the circuit net losses is provided to compensate for variations in line attenuation with weather. The over-all distance over which satisfactory operation is obtainable is limited by the type of open-wire line used and by the absence of automatic gain regulation. (See table III for specific distances.) With two repeaters these distances can be more than doubled but some narrowing of the transmission band results due to the transmission characteristics of the carrier repeater. For this reason and because no automatic regulation is provided with the system, it will generally be desirable to limit the number of repeaters in any one system to two.
    d.	A source of 105- to 125-voIt, 50- to 60-cycle a-c power is required for the operation of the terminals and repeaters. No power is required for the line panels.
    e.	Type H carrier equipment is moisture-resistant and is designed to operate over wide ranges of temperature and humidity. It uses the same frequency bands as the commercial (Western Electric type H-l) carrier equipment, and may be interconnected with that equipment. However, this commercial equipment uses East and West terminals, which are not interchangeable, with built-in ringing equipment.
    2
    carrier	nigh-	high- carrier
    TP TERMINAL	pAee	p.ee	TERMINAL	TP
    _ 0A-.3/FC	_ riL “R	;L”B _ 0A-I3/FC
    ______T~ (WEST)	(EAST) I_________
    ------1	 OPEN WIRE PAIR	 i-------
    LOW-	LOW-
    TP	PASS	PASS	TP
    FILTER	FILTER
    ---	---*------------------------i---	---
    CARRIER	CARRIER
    FILTER	FILTER
    F-36/FC	F-36/FC	TL	51566
    Figure 2. Type H carrier superposed on open-wire pair, block diagram.
    2.	Table of Major Components
    The major components of type H carrier telephone packaged equipment are listed below. The weights and dimensions shown are for the equipment unpacked and ready for use. Installing materials and spare vacuum tubes furnished with the equipment are not shown. See the Signal Corps catalog for a complete list of small parts, or appendix I of this manual where the list is included for reference.
    Component	Weight unpacked (lb.)	Dimensions (in.)	Mounting plate spaces required
    Carrier Terminal OA-13/FC	50	12J4 X 19	7
    Carrier Repeater OA-IO/FC	35	8M x 19	5
    Carrier Filter F-36/FC	15	3^X 19	2
    3. Physical Description of Panels
    Each panel is made of sheet steel and is arranged to be mounted in an apparatus cabinet or on standard 19-inch relay rack. Controls for operation, jacks for testing and patching, and designation card holders are located on the front of the panels. The terminal strips for terminating connections to other equipments are located on the rear of the panel, together with the power cord terminations. Shipped with each panel are schematic and wiring diagrams, copies of this manual, and four designation cards.
    a.	Carrier Terminal 0A-13/FC (fig. 3). This panel contains equipment for changing voice-frequency signals to carrier-frequency signals in the
    transmitting direction, for reconverting carrier-frequency signals to voice-frequency signals in the receiving direction, and for amplification of the signals to the desired strength in both directions of transmission. The EQPT switch is used for arranging the terminal for the type of termination desired, two-wire or four-wire. The LINE switch is used to arrange the terminal for the type of line connection desired, to an East line, a West line, radio transmission, or radio reception. The REC GAIN and TR GAIN controls are used to vary the losses of the transmitting and receiving gain pads, and thus control the signal strength. These pads provide losses up to 50 decibels (db) in 2-db steps. One vacuum tube is used in each of the amplifier circuits, transmitting and receiving, and in the oscillator circuit. Six spare vacuum tubes are shipped with the equipment.
    b.	Carrier Repeater OA-IO/FC (fig. 4). This panel contains equipment for amplifying the signals in both directions of transmission. The strength of signals is controlled by the W-E GAIN and E-W GAIN switches, which in turn control the amplifier gain pads and provide up to 50-db loss in 2-db steps. One vacuum tube is used in each amplifier circuit, and six spare tubes are shipped with the equipment.
    c.	Carrier Filter F-36/FC (fig. 5). This panel contains high-pass and low-pass filters for separating the voice and carrier frequencies, and balancing filters for use with the balancing networks of voicefrequency repeaters. Enough balancing filters are provided for balancing purposes when the carrier equipment is used on a physical two-wire line or on a phantom group. This panel, is connected between
    3
    Figure 3. Carrier Terminal 0A-13JFC, front view.
    Figure 4. Carrier Repeater OA-IO/FC, front view.

    1TL5I5541
    4
    the line and a terminal or a repeater. Two of these panels are connected back-to-back when it is necessary to terminate the voice circuit at an intermediate point in the system, to by-pass the carrier system
    around a voice-frequency repeater, ot to transfer the carrier circuit from one open-wire line to another open-wire line. Connecting wire (205 feet) is shipped with the panel.
    Figure 5. Carrier Filter F-36/FC, front view.
    4. General Functioning of Terminal Panel
    a. Two-wire Telephone Transmitting Circuit. A terminal arranged for telephone operation and terminated on a two-wire basis on the switchboard side is shown in figure 6. With switch EQPT at 2W, and switch LINE at EAST or WEST, as required, the carrier terminal operation is as follows:
    (1)	Voice-frequency signals pass through the hybrid coil HYB and enter the transmitting portion of the low-pass filter LP. The balancing network (BAL NET) connected to the hybrid coil is used to balance the two-wire side of the hybrid coil.
    (2)	The output of the low-pass filter connects to balanced varistor modulator MOD. The modulator, which raises the voice-frequency signals to carrier frequencies, is supplied with a source of 7,150 cycle current by vacuum tube oscillator OSC.
    (3)	The modulator output is connected to bandpass filter BF arranged to pass the upper side band (approximately 7,400 to 10,150 cycles) if it is an East terminal, or the lower side band (approximately 4,150 to 6,900 cycles) if it is a West terminal.
    (4)	The selected side band passes through the transmitting gain potentiometer TR GAIN, which is adjusted by control TR GAIN on the front panel, to the input of transmitting amplifier TR.
    (5)	From the transmitting amplifier the side band passes through directional filter DF which provides additional suppression for the unwanted frequencies. The transmitting portion of the directional filter is
    arranged to pass the same side band as passed by transmitting band-pass filter BF.
    (6) From the directional filter the carrier side band passes to the open-wire line through the carrier line panel high-pass filter and through protector equipment.
    b. Two-wire Telephone Receiving Circuit. The incoming side-band path is as follows:
    (1)	After passing through the protector equipment and carrier line panel, the receiving unit of directional filter DF selects the lower side band if it is an East terminal (the upper side band if it is a West terminal) and passes the side-band frequencies through gain control potentiometer REC GAIN, which is adjusted by the REC GAIN control on the front panel. The side-band frequencies then pass through band-pass filter BF, arranged to pass the lower side band if it is an East terminal, or the upper side band if it is a West terminal, and thence to demodulator DEM.
    (2)	The demodulator is a balanced varistor bridge and is supplied with a source of 7,150 cycle current from the same vacuum-tube oscillator OSC that supplies the modulator. The demodulator lowers the carrier frequencies to voice frequencies.
    (3)	The voice-frequency output from the demodulator is connected to the receiving portion of low-pass filter LP and thence to receiving amplifier REC.
    (4)	From the receiving amplifier the voice-frequencies pass through a 7.6-db fixed loss pad R2 to hybrid coil HYB and then to the two-wire extension.
    LINEHUEH j gg NETWORK
    Bline filter ■ BALAN^
    HMHTiGHHPASsHMHH^^HfLOW^MSsBBBMBrpHANTOhujNE	HlINE FILTERP”
    BESE FILTER	‘	FILTER BL’-"'' » FILTER BALANCING K BALANCING NETWORK]
    5
    LP	MOD	MOO	BF	TR GAIN	TR
    ___________________r------------?_____________________our 	r------~i 	 l" XMTG [______________________________[ BAND- I	XMTG_V"\
    I L0W'	MOO	r—<)	I PASS 1	CAIN	XMTo\
    I	I -	I
    H ।	’ J-------------q ----------- [X -
    0-5,000- |	7,4 0 0-10^150 — EAST
    (4,150- 6,9 00- WEST)
    i	।	rA---.-!---,
    I	|	7,400 - 10,150- EAST	©■«	D-
    *	I	I	(4,150 - 6,900 — WEST) I f.L	I	*
    . -	1	I	| I	• lL-. I; -
    »	;	।	z	।	!	a- £
    *7	° ~	HVB	I	1	I	I	• »
    — ---------m------------i	——	।	।	-^5	I i _____________________ । I d v -
    ex^on	77	7 I I ------------------------------- j i "ZZ^Z ;;;» I ] H d0™.
    ? S	•	I	।	I '------- 50-60- I	1	gZg	LINE FILTER
    h—t	I	7150- —■■ ■■	I	CIRCUIT ___ I	I
    R2	7?;°B	[	I	[	I	AJSO-.^V- t.ST 1	O'"
    J	I	|	(7,4 00 - IC,. 50-WEST; I	f 1 L.
    W	i i	O
    |	।	4,150 - 6,9 00 - EAST
    REC	I 0-S.000-' *	DEM	OEM 0 <7-4°°' l0-150' *EST’	REC GAIN
    ------------H-------------------------------------s%----------------H------------------------------
    /	I	RCVG	,	J (o	—.
    _	ex >o	I band- I	hcvg
    / RCVG __ |	LOW-	।	__D C	.	.	KCVto
    < AMPLR - pASS	I	--<>	I	PASS	।	GA.N
    j F|L	।	jo	I	FIL	I	p0T
    ----------------------------L j-----------	----------------------_L J____________-------	_________________ 1 Llz—__U--------------------------------------- lJ-ZZ"__U 1---------------------------
    SWITCH SETTINGS
    4 W
    1	4W	WEST -s z— TRANS I
    2W“\	/”TLG *‘*C EAST—\	REC ftA°'°
    EQPT	L,NE
    , _________________________
    Figure 6. 7 ype H terminal terminated on a two-wire basis, block diagram.
    6
    c. Four-wire Circuit (fig. 7). With the EQPT switch at 4W TEL and the LINE switch at EAST or WEST, as required, the terminal circuit is similar to that described in a and b above except that the function of hybrid coil HYB is changed to that of a repeating coil, an 8-db pad R1 is inserted at the input to transmitting low-pass filter LP, and the 7.6-db fixed pad R2 is eliminated from the receiving path. The terminal is terminated on a four-wire basis when the type H carrier system is extended to another adjacent carrier terminal, an adjacent voice-frequency telephone repeater, or a voice-frequency carrier telegraph terminal. The 4W TLG position of switch EQPT is provided for cases where it is desired to remove the 8-db pad R1 from the transmitting path.
    d. Radio Link Circuit. When a type FI carrier system is operated over a four-wire radio link, two terminal panels are required at each end of the link. The arrangement at each end of the link is shown in figures 8 and 9. For explanatory purposes, the terminals used at the West end of the radio link have been arbitrarily designated 1A and 2A, and those at the East end IB and 2B. Transmission and reception are described only for the West-to-East path; East-to-West transmission follows a similar path. The arrangement consists essentially of connecting the receiving circuits of the carrier terminals to the radio receivers, and the transmitting circuits to the radio transmitters.
    (1) West End of Radio Link (fig. 8). Voice frequencies (250 to 3,000 cycles) from type H telephone channel 1 enter terminal 1A, are raised by modulation to carrier frequencies (7,400 to 10,150 cycles), and passed by directional filter DF through the carrier line panel to the radio transmitter. Voice frequencies (250 to 3,000 cycles) from type H telephone channel 2 enter terminal 2A, are raised by modulation to carrier frequencies (4,150 to 6,900 cycles), and also passed by directional filter DF of terminal 1A through the carrier line panel to the radio transmitter. Note that terminal 1A is called the transmitting terminal and that terminal 2A the receiving terminal. The LINE switches of the respective terminals are so positioned.
    (2) East End of Radio Link (fig. 9). Carrier frequencies from the radio receiver, after passing through the carrier line panel, are separated by directional filter DF of terminal 2B. The higher frequencies (7,400 to 10.150 cycles) are passed to terminal IB, lowered by demodulation to voice frequencies, and transmitted to type H telephone channel 1. The lower frequencies (4,150 to 6,900 cycles) are passed to terminal 2B, lowered by demodulation
    to voice frequencies, and transmitted to type H telephone channel 2. Note that terminal 2B is called the receiving terminal and that terminal IB is called the transmitting terminal. The LINE switches of the respective terminals are so positioned.
    c. Talking Arrangements from the Terminal Panel. If it is desired to talk over the type H carrier system, it is recommended that the terminating switchboards be used since no facilities are provided for talking from the carrier terminal. However, if it is necessary to talk between two terminal panels, a magneto telephone and a patching cord with spade terminals at one end must be available at each terminal. Connect the spade terminals to the magneto telephone. Remove the system from service, insert the plug of the patching cord into jacks 2W HYB on the terminal, and set switch EQPT on the 2W position. (The hand generator of the magneto telephone cannot be used to signal over the system from the carrier terminal.) After the conversation is completed, restore switch EQPT to its original position and remove the patching cord. Echo or hollowness may be noticed when talking over the system in this manner, but such echo does not indicate trouble unless echo is noted also when talking between the terminating switchboards.
    f. Power Supply. The carrier terminal requires an external source of 105- to 125-volt, 50 to 60-cycle, a-c power. Equipment is provided in the panel to convert this power to 10.5 volts alternating current (ac) to operate the heaters of the vacuum tubes and approximately 150 volts direct current (de) for the screen and plate circuits. The carrier terminal panel provides no fuse or alarm circuits.
    5.	General Functioning of Repeater Panel (fig. 10)
    a.	Transmission Circuit. For the West-to-East direction, side-band frequencies enter directional filter W DF which selects the correct frequency band (4,150 to 6,900 cycles) and passes it to gain potentiometer W-E. This potentiometer is adjusted by the W-E GAIN control on the front of the panel and controls the strength of the signal passed to amplifier W-E, which amplifies the side band to the desired level. The amplified side band then passes to the open-wire line through directional filter E DF, the line panel, and protector equipment. For the East-to-West direction, the operation is similar to that described above.
    b.	Talking Arrangements. It is impractical to talk over the carrier channel from a repeater. When talking from repeater offices, a voice-frequency circuit must be used.
    7
    /	t O	_
    A.	’	'	uv_	.-------,	M0B	BE	TR GAIN	TR
    Y (_	---------________f|---___________________MOD OUT	r~----1
    H	8-OB 5^ F tow- [	F BAHO- 1 XMTG pX~
    _____®______m____________I UpfL O ?? o I L lx OMITTED WHEN	| °"AOOO — I	E400 - 10,130 - E AST
    COPT SWITCHON	.	1	(4,150 - 6,900 - WEST )
    II	I I	r ~-----—I
    7.400- 10,150- EAST .	OIR	|	“
    |	|	fAiso - ^900 - west ) I fil	| DF -
    i	liri -
    I	OSC	|	I	I	I	o 3
    1	l~~ I	1	1	----- I 1-----------------1------r 1-------
    TO 4-WIRt	I	I	----- I	I	_ POWER ------ I	k-H TO CARRIER
    C?^UCJ'NS|	1	I	’•'S'0'	1	। P । SUPPLY 'so-M5*	I	glS LINE FILTER
    I I o~[	; I •	—	_1________h________
    ; I	। I	l_|______Il
    ।	^150-6,900— CAST *	OIR
    I	,	।	C7.400-10,150 - WEST ) |	FIL
    I 1	I I	II
    s 5	i i	ii	l!_i____l. b
    * °	|	|	Al SO - 6.900- CAST
    j 3	।	( 7,4 00 - 10,150-WEST )
    Al, ’ S	REC	| 0-3,000- I	D€ M	OEM 0	|	।	REC GAIN
    m	y7 F 1	—baho- i Rcvs
    TZJ-Q	4/RCVG	1 LOW- .	y C	I	C S
    =x=»	\AMPLR I I _4<._	1	0EM	< Z>	I PASS	GAIN
    ? S	I I PASS I	 M0D	!	■>	TR GAIN . TH
    VA	CZ	।------ 1	------ 0UT	, -----I	------ \
    ————— XMTG	“	1 ■ ■ *\ /	..... ■	“““““““XMTG “
    E0PT	< i-'NC	; LOW- ; moo ,4 s	; p*ss' !	xmtg\ _________
    ~	____ . ...	- J	I PASS	A) fc>	I F?U >	CAIN AMPLR^/
    t— -------H p|i	H—L__J—c--------------------------------H IL H-----------------ctrl \- ^-----------------1	?
    A7	HYB	!0-3.000vC I	] 7,400- I	fl--------1	H J
    W- —	■[	fr—|	i	[	i IO,l5OvP ।	l| 1— —1|	J £
    ._____HYep|o bal !	1	;	;	; D’.«oo'-L i °f « z
    ■'7hT” ■yf COIL net- :	: osc	;	:	LJ____________ai
    ■ I o	5*~~1	_______L—1	'	--- <	I	'	'	; k 3 THROUGH
    A®	a «■	II,	I	J 7?50\r	‘	CARRIER LINE
    O £	i	7,150 o' - ,	I	,	a-<=	PANEL TO
    “	R2 7.6-OB	. ______ _L	>1	I----•" h—4	RADIO XMTR
    °	5	pAD	-	,	,	I	-----,------
    «M	--»—| 	, 4 150- .	Il   II	A2
    I REC .	10-3,000vP , DEM OEM	, 6,900s/' ,	REC GAIN	1 R1'.,lnFIL 1
    I	। —— .	------ IN v	,	r.	| 4150-	।
    •---------L RCVG '-----------------, jo-pTyg—	.	*	-L...	^-r-	_____________ 6 900v/'1	,
    7 (°	। FIL ।	CTRL ________
    -±-1-------1	I Bl B3. I L---------1 I BS B7 I	I ^l0
    bX\/ £ r hl- -I H J
    4 X	,__________' FIL -1_____ _________3 E____________________L fit- J________________	_ -S	1 OIR FIL 1 t “■
    g j	I___	------ 1	------ “________________________________p	_____p	i 7,400-	।
    A7	o 	1	I______fc- »]_____ RADIO RCVR
    A8	l~f	I	i 7.150^	I	--II;	?2
    --------------------------------------1-1-- i	I	'	■ OIR FIL 1 f---—-----*----------------------«-0B R2 I	------ A.	,	,	; 4J50-	•
    ( Vitsi-	P*D	.	; e.aooj'
    w	I	l.l	(	(	I	■ "* ’
    T|EL EAST"1 \ r-TRANslS	I REC . 0-3000./' , DEM	OEM D	1 10,150./' i	REC CAIN
    2W~\ 1 '4t?G 1 /^REC $	1—^1—fTp-LJ------------------------L_p^G_J	|_J----=4-------------------
    za	zr\ 1“ /rcvg : low- ;	; BAND’ :	■ RCVG
    \AMPLR 1 , PASS I	DEM	2,	' PASS ,	GAIN
    \\ Vs	// //	। r 11	•	w f	1 FIL '	CT RL
    EQPT	LINE	JL
    ____	,_____ ______________ ’	TERMINAL 2 A	Tt 51569
    SWITCH SETTING__________________t,
    TERMINAL 2A
    Figure 8. West end of radio link, block diagram.
    8
    9
    SWITCH SETTINGS
    TERMINAL 20	__________terminal 2b__________
    ----------------------I~T—.	: r~~T 	 _____________ .fF^1 r\	™ 4west-| )o RCVG	' BAND- '	o| C" “_______I HCVC --------	TEL j EAST TRANS £
    ■*"	CA'N	■ PASS j	7 >— DEM ' LOW- । RC*GJ\	2W—x	4W '	/ ,-REC <
    |——_________________ ctrl  f	I EIL I	' PASS ' I	Ttlg	'
    ___ ______ REC CA'N	I ? 400- 1	D OEM	IDEM	I	i I	I____X\\\	/Z/7 ri-i-i ■]	(.oisolp 1	in	,0-3.000^:4- I__________________	\\	////
    , DIR FIL	1 ’ I	.	.	*	# //
    ,	4,130-	,	।	i	,	,	7.6-DB	EQPT	LINE
    '	6,9003	,	I	I	------ ,	,	PAD
    ■	____________ .	' t I—'•	'	I	----- OSC '	'	I J—	------------------------------
    THROUGH	fe-'-f___-I	'	1	I	— 7i,nn 1	1 ---1—-I ' 1 ---------- ----------6®______
    CARRIER LINE X 4	►(	I	I	,	| T.I30vP ,	I	0_»?
    PANEL TO	CF=>—■=>	'	'	1	i	~ ------- I	' BAL HYBRID	/ . <
    RADIO RCVR	( J)-----*■'	!	II	i	' NET rnu	TELEPHONE
    <*	0	— I 1	II	1	a__J,	CH2
    Al	Hl-	'l-i— ---11	| 4130- 1	'	I —	J* t	7
    z c on voo'- !	ai ------ '.0,0004;	_______ !0-3,0003,;	III HYB ? £	*7
    I 10,1503 1	J ~	~ — — —	— — _______ —  —.	-	1	I_________I	1	£
    “	“	J---1-1--I,	/XUTC XMTG	I BAND- I	J CU	I XMTG ,	J.	J °
    j □	‘---1'-]--‘	\AMPLR GAIN	1 PASS ]	<	•	“00	I LOW-	N
    a	|	X _ CTRL ________________! FIL I	(0___	I P*SS |
    I \b9B.J J TrA TR CAIN lB8 BJ !	•	|b2 bJ	M00 I------------ I
    BIOXI XI rr JJBII	R.\ >1 rf	J V X, rf S	1-------1
    /	85 X X87 BF BILL Tqrr zrBJ	LP
    Be4/y/\\B6	S C DEM	I L0W“ ' RCVG\.^ 1 Tdir Fil I' ------------CTRL _____ 	L F,L J_____	r AMP5>^
    ; 4,150-	1	----- m--------------------M	°T=j=l o'	—I_______—- FIL Tl	—I
    6,9003	1	REC GAIN	l 4 150- I	0 DE“	OEM	I ,	i-L1^
    .	'L~T1----11	' 0,9003 I	IN	'0-3,0003,- REC I I
    THROUGH	1	'	|	!	1	------- '	7.6-DB	> a
    CARRIER LINE <4-4	I	'	( ____ PAD R2	O
    PANFL TO	,1	'	l	OSC ।	I	U	i «
    RADIO .XMTR	I	;	1	1	7,1503, I	1 ---- 1 J-----	7,7
    *'	6 b J DIR FIL I'	11	~	|	1 BAL HYBRID	Xv-A	TYPEH
    - C	J 7,400-	1	t	I	,1 NET. COIL ----------------► AS TELEPHONE
    u, w OF. 10,150 3,	1	II	,	'	7__CHI
    5 ! l-i.°i. u	: 7,400- •	:	:_____k-L..---------------------------—
    a	|___________ I 10.150 3, ;	,0-3,0003, I	HYB__________________A 7_______ ,
    ®	^XlTC " X“TC	7 BAND-"-------------------LC------	----HX“TC H-----------J-	LifwEST—7
    /XMTC GAIN	I p...	,	°J C	LOW-	~	4W	tr |WEST 1	.
    \AMPLR	PASS 1	r >—*	MOD I	1	FEL	EAST—. 1	12
    CTRL	| FIL I	JL	। PASS ,	'LL J1*5'-] pTRANS 5
    ~1	---------------r	“— ------------------------ ----------r FIL J-------------	2W~\ I	' /-RECkJ
    TR TR GAIN	[	J	“0D	. -----H	-- 4TLG	J
    - - ----1	out mod ।-----------------j	ri 1
    eF	lp	wax	/r\f
    TERMINAL IB	\\	//
    EQPT	A# LINE
    t	----——----------	— ----	>
    SWITCH SETTINGS TERMINAL IB	TL5I37O
    Figure 9. East end of radio link, block diagram
    10
    c.	Power Supply. The repeater power equipment is similar to that used in the terminal. An external source of 105- to 125-volt, 50- to 60-cycle, a-c power is required. The repeater power supply pro
    vides 10.5 volts ac for the heaters of the vacuum tubes and approximately 150 volts de for the screen and plate voltages. The repeatei- panel provides no fuse or alarm circuits.
    W-E	W-E
    ------------- GAIN 	 ________________  POT. L,____________________________AMPUU>_
    L I
    i  ~— W DF	E DF ' i CELL 1
    I	OIR	.	L ;	0|R~L ,
    ■' ,FIL, -	; fil p
    T----------ur-—j—FT ; h 	; W— ----------- ------------
    CARRIER	L|*E	DIR :	;	H2--- PJP	105-125V	I	j D^R	..O., E	TO
    LINE PANEL	FILT	FILT [	.	P------U LY	50-60^	i	[ FILT	LINE	CARRIER
    p—-) LINE ;	I	c___ CIRCUIT -- I	. L|NE	FILT LINE PANEL
    — M ill i ~	;	|—i——------------------
    L®j '
    ---------------------------- GAIN
    < AMPLR
    ------------------------ POT -------
    E W	E - W	LSI56O
    Figure 10. Type H repeater, block diagram.
    6.	General Functioning of Line Panel (fig. 5)
    The line panel provides the line filters and balancing equipments required for use with terminal and repeater panels and at transfer points. Five separate units, which may be connected as desired, are included.
    a.	Line filter LF consists of two sections, a low-pass and a high-pass filter, for separating the voice and carrier frequencies.
    b.	For phantom-group operation, it is necessary that both side circuits of the phantom group be kept electrically identical. Line filter balance LFB is provided for this purpose and is connected in series with the line wires of the other side circuit, when this circuit is not equipped for H carrier operation, to balance the line filter on the carrier side circuit.
    c.	Line filter network LFN is connected into the balancing network of a voice-frequency repeater to balance line filter LF.
    d.	Line filter balancing network LF BN is connected into the balancing network of a voice-frequency repeater to belance line filter balance LFB.
    e.	Phantom line filter balancing network PH LF BN is connected into the balancing network of a phantom voice-frequency repeater to balance line filter LF and line filter balance LFB in the side circuits.
    7.	Electrical Characteristics
    a. Frequency. (1) The frequency range of the type H carrier system is from approximately 4 to 10 kilocycles.
    (2) Frequency bands are obtained by modulating a common carrier frequency of 7,150 cycles with the frequencies produced by the voice. Single side-band transmission is utilized, the carrier frequencies and unwanted side bands being suppressed. For transmission in the East-to-West direction the system uses the upper side band (approximately 7,400 to 10,150 cycles) and in the West-to-East direction it uses the lower side band (approximately 4,150 to 6,900 cycles).
    b. Transmission-frequency Characteristics. Since equalization is not provided in type H carrier Terminal equipment, the transmission-frequency characteristics of the system depend largely on the terminal equipment and on the attenuation characteristics of the line over which the system is operated.
    (1) Without repeaters. In a system operating without repeaters, generally it should be possible to obtain transmission bands having losses at 300 and 3,000 cycles not more than 10 db above the loss at 1,000 cycles. A representative over-all frequency
    II
    characteristic for a type H carrier system operating over a 145-mile line of 104 copper-steel (40 percent)
    open wire without intermediate repeaters is shown in figure 11.
    20 ——।-------------------------------------------------------------------------
    19-----------------------—------------------------—----------------------------
    18--------------------------------------------------------------------L________
    n  -------------------------------------------------------------------1__— ----
    «> ----1-----------------------------------------------—--------------1----------
    ■ 15 ----1	----------------/—j---------
    „ 14-----1----------------------------------------------------------/ |---------
    	I \	fl
    \ W + //•.
    ' x	WEST TO EAST--f
    6------------------—	---------------------------------------------------
    5---------------------------------—	-----------------------------------------
    4---------------------------------—--------------------------------------------
    _________________I I I I I I I I I I I I I I
    400	800	1200	1600	2000	2400	2600	3200	3600
    FREQUENCY-CYCLES PER SECOND	TL 51312
    Figure 11. System transmission-frequency characteristics.
    (2) With repeaters. When one or more repeaters are used in the system, some narrowing of the over-all transmission band results due to the attenuation characteristic of the additional line and the directional filters in the repeaters.
    (a)	Additional losses at upper and lower frequencies due to one repeater in the system are given in table I. This table shows losses referred to the loss at 1,000 cycles and is based on the gain-frequency characteristics for a representative repeater but does not include the attenuation effects of additional line.
    Table I. Additional losses at edges of bands due to one repeater
    Frequency	East-to-West loss	West-to-East loss
    (cps)	(db)	(db)
    250	4.5	3.0
    500	1.5	1.1
    2,500	0.2	0.2
    2,750	0.8	0.6
    3,000	1.5	2.8
    (b)	Where more than one repeater is involved, the losses given in table I should be increased accordingly. Since no equalization is provided with the repeater, the attenuation-frequency characteristic of the additional line reduces the rounding-off effect at the lower edge of the East-to-West bands and the upper edge of the West-to-East bands. Correspondingly, it increases this effect for the lower frequencies in the West-to-East band, and the upper frequencies in the East-to-West band.
    c.	System Load Capacity. The system is designed to transmit an output power of about +16 dbm to the line. With the system properly adjusted, speech or telegraph currents should not cause appreciable overloading. When the terminal is arranged for two-wire operation on the switchboard side, powers up to +2 dbm can be delivered to the switchboard without appreciable distortion, and powers up to +5 dbm can be used if some distortion is permitted. When the terminal is arranged for four-wire
    12
    operation on the switchboard side, the system is arranged for an input and output of -fi-4 dbm on the switchboard side.
    d.	Signaling. The type H carrier system requires voice-frequency ringing equipment at each terminal. Ringing equipment is not part of the type H system and must be provided separately.
    e.	Power. (1) The 105- to 125-volt, 50- to 60-cycle, a-c power source required by a type H carrier terminal and repeater is used to supply power to the vacuum tubes. The terminal uses approximately 20
    watts of power and the repeater uses approximately 15 watts.
    (2)	A testing power, equivalent to one milliwatt at the two-wire input, (for circuits having extensions with a loss of 0.5 db or less), normally is used in setting up and maintaining a type H carrier system. All input and output powers in this manual are referred to this testing power. Power is expressed in dbm, which denotes power in decibels above or below 1 milliwatt (Odbm), terminated at 600 ohms. A plus sign is used to denote powers above 1 milliwatt and a minus sign for powers below 1 milliwatt.
    Section II. APPLICATION
    8.	System Application
    By utilizing a band of frequencies higher than the voice-frequency band, an additional telephone channel may be added to the channel already existing on a pair of telephone wires. Type H carrier equipment is designed to provide such a band of carrier frequencies for operation over an open-wire-line circuit. Operation of the type H system above the physical voice circuit has little effect on the physical circuit because the filters of the type H line panel prevent interference between the voice and carrier frequencies. The carrier system may be superposed on an open-wire pair terminated in voicefrequency repeaters, or on a nonrepeatered circuit-providing it is terminated in repeating coils. Furthermore, the pair may be simplexed or composited for d-c telegraph operation. The type H carrier terminals may also be arranged for operation over radio links.
    Note. In the applications described in the following paragraphs the switchboard sides of the carrier terminals are terminated on a two-wire basis for connection to a switchboard, two-wire extension, or two-wire voice-frequency carrier telegraph equipment. If desired, however, either or both of the carrier terminals can be terminated on a four-wire basis for connection to another carrier system, a voicefrequency repeater, or a four-wire voice-frequency carrier telegraph terminal.
    9.	Application to Two-Wire Physical Circuit (fig. 12)
    This application illustrates the use of type H carrier equipment with voice-frequency telephone repeaters and d-c composite telegraph sets. Type FI carrier equipment is inclosed within heavy lines and other equipment which must be provided in addition is inclosed within dashed lines. Note that voice-frequency ringing equipment must be provided for the
    carrier telephone circuit, and that protector equipment must be provided separately. The following variations of this application may also be utilized:
    a.	Without a Carrier Repeater at the Intermediate Point. In this case the high-pass filters of the two carrier line panels at the intermediate point-are connected together directly.
    b.	Without Voice-frequency Telephone Repeaters. If the line is to be composited for telegraph operation, the voice-frequency ringing equipment must be retained, the voice-frequency telephone repeaters are replaced by repeating coils, and the line filter network portion of carrier line panel is not used. If the line is to be simplexed for telegraph operation, the voice-frequency ringing equipment for the voice-frequency telephone circuit and the composite sets are eliminated, and the voice-frequency telephone repeaters are replaced by repeating coils.
    10.	Application to Two-Wire Phantom Group (fig. 13) Type H carrier operation over each side circuit of a phantom group is entirely satisfactory within the limitations of an FI system provided the pairs are transposed for both carrier and phantom operation (par. 166). This application illustrates the use of type H carrier equipment on the side circuit of a phantom group with voice-frequency telephone repeaters. Type H carrier equipment is inclosed within heavy lines and other equipment which must be provided in addition is inclosed within dashed lines. The arrangement of the type H carrier balancing network equipment has been omitted from figure 13 for clarity, but is shown in figure 14. The following variations of application shown in figure 13 may also be used:
    a.	Without a Carrier Repeater at the Intermediate Point. In this case the high-pass filters
    13
    CARRIER	CARRIER	CARRIER	CARRIER
    LINE	LINE	. LINE	LINE
    ——1	PANEL	PANEL	PANEL	PANEL ______
    --------1----1-----	------------I—।	!—J	___________L_.	I---1	_____________r-----,________ CARRIER । V-F I----CARRIER	HIGH-	CARRIER	ranniFn
    TELEPHONE I RINGING I	TERMINAL	PASS	HIGH-	REPEATER	HIGH-	HIGH- tcduiuai	CARRIER
    CIRCUIT | EQUIP	PANEL	FIL	?ASS	PA NEL	PASS	PASS	[RINGING | TELEPHONE
    ________J_____________		 FIL	PANEL	fil	F|L	PANEL ____________| EQUIP j CIRCUIT I ।	TiTH—1	!~W---------------lir1	—"H	—T	1—	H—i	FiTi--------------iVh	|—”■■[	—T
    —77-j	1—।	,	^lISL	।	‘-l^l	Is1!'*1	1	______1_____________
    telephoneIringTng’	I ----------------------Ms--------------------UH-------------__________	____FIL J-------HSETH’1--------;------l§HSET|--------*- FIL----1	I V-E | V'F
    c'-’ou.t [equip |_ ________________ Tr L J	lL LnJ -------------- --------------------- 4-r1 I J	L“IW --------------- I	louTl TE^rPcHuT
    1	I	I I ■"
    O-W	I	o-W	I	1
    V I	PAIR	V"F 1	PAIR	V-F I
    I Tp I	TP	W
    I REPTR	I REPTR	REPTR I
    I	TOO-C	TOO-C	I	TO O-C	TO D-C	. I
    TGEQUIP	TG EQUIP	|	TG EQUIP	TGEQUIP
    I	E!"E	LINE	J	]	LINE	LINE	I
    I	I	F'E	FIL	I	FIL	FIL
    _____________________________NET’	NET-_____________|......|____ NET.-----------------net.	•	| _________________—-H-zz—	L.	---------------------------------------------------------------------------------1 .________________WEST TERMI-NAL——————	■■■--	 ■■‘INTERMEDIATE	------------------------/	---- EAST TERMINAL	—	 S
    ru’nna
    Figure 12. Application to two-wire physical circuit.
    14
    of the two carrier line panels at the intermediate point are connected together directly.
    b.	Without Voice-frequency Telephone Repeaters. If the line is to be composited for telegraph operation, the voice-frequency ringing equipment must be retained, the voice-frequency telephone repeaters are replaced by repeating coils, and the line filter networks are not used. If the line is to be simplexed for telegraph operation, the voice-frequency ringing equipment for the voice-frequency telephone circuits and the composite sets are eliminated and the voice-frequency telephone repeaters are replaced by repeating coils.
    c.	Type H Carrier on Both Side Circuits. In this case each side circuit is arranged in the same manner. I he line filter balance units are not used since the line filters will balance each other.
    d. Type H Carrier on One Side Circuit, Another Type of Carrier on the Other Side Circuit. In this case the arrangement of the type H carrier side circuit is similar to that shown in figure 13 except that a line filter balance unit and a line filter network, to balance the other carrier line filter, are connected into the line and network sides, respectively, of the voice-frequency telephone repeater line equipment. An application with type H carrier on one side circuit and type C carrier on the other side is shown in figure 15.
    I I. Application with Radio Link (fig. 16)
    This application illustrates the use of type H carrier equipment with a four-wire radio link, providing two telephone channels in addition to the existing voicefrequency channel on the radio link. The arbitrary terminal designation 1A, 2A, IB, and 2B agree with those discussed in paragraph Ad (figs. 8 and 9). Any or all of the channels may be used for voicefrequency telegraph operation, but if only one channel is so used, the original voice-frequency radio channel should be used and connected on a four-wire basis, as shown. Since two carrier terminals are required at each end of the link, full utilization is generally obtained by operating two type H channels over the link. If voice-frequency telegraph operation is not desired, the four-wire radio circuit either must be terminated on a two-wire basis or connected to a voice-frequency telephone repeater on a four-wire basis.
    12. System Lay-out
    The operation of a type H carrier system over an open-wire line presents transmission problems not encountered in voice-frequency transmission due to the higher frequencies used by the type H system.
    CARRIER	CARRIER	CARRIER	CAnnrrn '
    LINE PANEL	LINE PANEL --- LINE PANEL	LINE PANEL --
    TCLCpioNt ! RINGING I	TERMINAL pass'	MI0H' REPEATER H,GH-	H «"=«- CARRIER F V-r J carrier
    cmcu.T I equip I WaMneTL “l“	RPANETLER	TEpRaMN'eNlAL I “I
    ------1	1--- —__________h_____rl —	— h	rl —	—L___J-------- —^1 •-—।	1__________!s"U1lsT	— id5T hEM J	*—r—i---------
    TELEPHONE RINGING	|	2 |	I S Hl |--_	-A---j --1 §1----) 3-I-----1------ I I V-E , SIDE I
    CIRCUIT EQUIP I	I “ I	I V	H	I-	1	I 0* I	’ll	RINGINGI TELEPHONE
    ______I i I	I ---- UrTJ L -I	I_I Lnj	--- I	I ___ Lr-rJ 1 '	I I L-T-fJ	__ |	|	| EOUIP 1 CIRCUIT
    J ’ I 1_____________________________1 J ’ L
    ------j |-----1	।	to v-r	J	u j) ■	I		r n_______ TELE^H^NE I RINGING* | VOICE- I	°°	OPEN WIRE	fjo	OPEN WIRE	j	1	! V'F ! PHANTOM
    CIRCUIT * EQUIP |	| FREQUENCY |	o'?	PHANTOM CROUP	S'?	O'?	PHANTOM GROUP	C?	I FREQUENCY I ^EQUIp5 I ’’aRCuTf*
    ______1 J____1 RETPTRS I------V-----------------------T° V-P	! Tp ____________________________________________! I_____' ---------- I REPTR5	-|---------------------r	TP EQUIP	r---------------------------------I REPTRS	I______I ______r---q__I I--------------d------------P	I	1	d----------P----------I I____________r___l___ ™dRSNPci_____i	|—--------r pP}--------3	f—1lJ	Lj	r HFr------!"^r n-----—I	i
    ------i£i i i i*i£i £	pi iisX ili'P----------------------|	I—L-A— ______________________	kl i L _ J i li L—	I S" I I 3 I I 3 I I 5ET I BAL I I L__________________J ~J	L~J L-J LJ ■—J	—T|	L__| LJ L-J -----------------------r
    X	WEST TERMINAL	'	X-----------------INTERMEDIATE-----------Z	s>-----------EAST TERMINAL____VLSI***
    Figure 13. Application to two-wire phantom group.
    15
    PHANTOM GROUP
    C A RRIE R
    TERMINAL SID E 1 REP EATER
    OR
    CARRIER	------
    REPEATER	--------------- ---------------
    fTpTJ	----------L^lfn
    "1 1 n i u m
    r- PASS
    (._J-------------------------	! | telephone I l'”Lwo7kR
    1*77771^^1 CX H “LOW	I REPEATER	TO LINE
    ——_j£!_l	SET '-------L-pasS-------L- HYBRID -------- — AND CX
    ]O '	J	--- COIL	BAL NET.
    a L--r—r—----'	I  —----------1
    । i	---------- |	----------
    LINE FILTER LF
    TO D-C	I
    TG EQUIP	I---------------------------------------
    ।____________PHANTOM REPEATER______________
    _____L_L__,	—-_________ / PH LF BN
    |	V-F
    ,	। ---- TELEPHONE ---- PHANTOM   TO LINE
    REPEATER LINE FILTER AND CX
    I ---- HYBRID ------- NETWORK — BAL NET
    J	।	-------f—
    TO D-C	I	------
    TG EQU I P.	-------------•------------------------’----
    . ।	SIDE 2 REPEATER
    I |	I----------“-------------------------------
    [7o| I—L — -I--|	!	-------1
    Igl ,	1	V-F	-----------l/LFBN
    ____|H>I D-C L_ LINE FILTER	, TFI FPHONF ■	 ..^rrn-rro TO I INF । imc- iOl I CX I dai Akirr	DrorATrn_LINE FILTER	' LJ LINE
    L E	SET !— B L NCE I____________ RHYopTnR	BALANCING AND CX
    F	' rnn	network “ BAL NET.
    I er I I-_ J I———J	I	luil
    L F B |	L..........
    i	_____________r-.. ..
    i I—______________________
    TG EQUIP	I 1----------------■-------'	t	_____________________________
    I •
    I I I	I—1 I	I	-------1
    । j ।	•	iii	I	r———_—j————■,
    ' < I I”"1	•”']	LOW- I |	I-~|	|	---------------- TVPEH
    w— ■■ I g !—I	—I PASS l—| .	TYPEH	______ line	I TYPEC
    1,0 i I D'£$*	'	I [FILTER. |	EINA„	1 V-F TELEPHONE	filter I LINE	TO LIME AMT
    ! H ! I SET I	|	|	/.MLI	I	REPEATER	BALANCING | FILTER I	CX BAL KT.
    ' I o >------[	, !'	4	H------------- BALANCE --------------------- HYBRID COIL	------ NETWORK __JnETWORK |-----
    I Q . u---------j	I----1	----- |	‘l|
    ।	‘-------J LFB	| ------------------- ——-I	i____।
    LF BN
    •	'------- Z71-------------------——
    । <
    ।	-------------- \i-----------------------------
    -----r-1
    I_____________________________1________________
    Figure 15. Arrangement of balancing network equipment for phantom group operation, type II carrier on one side circuit, type C carrier on the other,
    Preliminary to the establishment of such a system, it is desirable that a survey be made of the facilities over which the system is intended to work. If the system is to be laid out by personnel in the field, this survey provides the basis for other considerations such as attenuation, impedance, noise, crosstalk, and operating distances. If the system is not to be laid out by personnel in the field, the survey data will be submitted to Office of the Chief Signal Officer, Army Communication Service, Plant Engineering Agency. This agency will lay out the system and provide the necessary equipment for operation of the system. Transposition lay-outs and drawings, if necessary, will be prepared to retranspose existing open-wire lines or for the construction of new lines.
    13.	Preliminary Survey
    Satisfactory operation of the system will depend to a large extent upon the degree of thoroughness with which the preliminary survey is made. The data to be compiled are listed below.
    a.	Geographical Lay-out. (1) Location of system terminals.
    (2)	Location of intermediate points where repeater equipment may be installed and maintained conveniently.
    (3)	Mileage of the line between each location in (1) and (2) above.
    6.	Line Facilities. (1) Decide whether a new line is required or an existing line will be used. Give details of plans in this respect.
    (2)	Information concerning gauge and composition of wire, and pin locations available for the system in each section.
    (3)	Length of crossarms, spacing between pins, and spacing between crossarms.
    (4)	Transposition system, whether existing or proposed.
    c.	Cable. (1) Type, length, gauge, number of quads, or pairs.
    (2)	Location of all intermediate and entrance cables involved.
    (3)	Type of loading, if any (loading coil inductance or type, and spacing).
    d.	Other Carrier Systems Involved. Where other carrier systems are existing or proposed on the line involved, supply information concerning:
    17
    YERMIMAL I A	TtKUlUAL 2 8
    carrier	Carrier	carrier	carrier
    TERMINAL	LINE PANEL	LINE PANEL	TERMINAL
    _____________________________________PANEL______ ___________________________ PANEL __________[------ ---------.__----------------------------- — j ______________________________________________________________r- '- - -I	__________ _______________________________I— --1__________
    F pF___tEL_
    [■	]--------------------------------------------[—1I  -------------[-	J—[---------------------------------------------------r	—]
    •	I	.	- ■	»	I	II ___________I
    I	!------*	------—►	. nw	------» AAOlp I	padio I______________________________________►
    pass'	------*• I *UTR	RCVR ,------„	pLA°s	i
    I-------------------------------------------FIL ------------------1 I	I i------------------L- r- C
    TELEGRAPH [ TELEGRAPH ]	|	I	1 TELEGRAPH [ TELEGRAPH
    CIRCUITS [ TERMINAL |	_ 1	*	• TERMINAL ' CIRCUITS
    I	■	__▼
    I	CHAN • CHAN	CHAN C^AN
    I	—	—	’	2 I
    ! , , ( , । , ! i-----------------------------------------------------low--?---------------{	;	i-	,— -----------1- low----------------------------------------------;
    PAS3 *------------ 1	1 J 1 *------------------ P*,SS
    I	«--------	hl	«-----I radio	ra0'° I ------ •"-----------------------------
    i	<-----। rcvr r	। XMTR „-------	(	I
    i---------------------------------------------f------------------r ।	i i----------------—--------------------------------------------------->
    I----------1	----- i---------------------1	I-----1	----- I____________________________________________________I
    -----------I —I------------ J I	HIGH- J	L HIGH-	I	I			FW-'1----------- rype M V-F-----------------------+-------J	_________ PASS	PASS	__________ ♦------‘	"»	I V r 1 Ivor M
    ,	'.RINGING1 --*------------------------------------- FiL	FIL	*	“	--- ♦ (RINGING I TyPEH
    TELEPHONE I £Qy|p I	T*PE h CaRRiLR Chan 1 ---- -________________________________________________________________ i EQUIP * TELEPHONE
    CHANNEL 2	’ »	---------------------------------------- 7	---------- -	----- । CHANNEL I
    |	I	<-------------------------------------------- TYPE H CARRIER CHAN 2--------------- ------------------------------------■*— ' '•  --------- ----------- |
    1-----J	1	_____ v-F CHANNEL	-------- ------------------- L----------------------------------------------------i
    CARRIER	CARRIER	CARRIER	CARRIER
    TERMINAL	LINE PANEL	L»NE PANEL	TERMINAL
    PANEL	PANtL	TL 31MB
    F£HMINAL 2 A
    TERMINAL 1 a
    Figure Id. Application with radio tmk, block diagram.
    18
    (1)	Type and frequency allocation of systems.
    (2)	Location of terminals and repeaters.
    (3)	Direction of transmission of frequency bands.
    (4)	Pin locations; gauge and composition of wire used by the systems in each section.
    (5)	Output power used on other systems.
    e.	Voice-frequency Terminations of Carrier Circuits. (1) Desired circuit net loss.
    (2)	Location of terminating switchboards. State whether they are adjacent to carrier terminals or reached by a second carrier channel or' by voicefrequency extensions over cable or open-wire lines In the latter case give the length of the extension, the gauge of wires and whether the circuit is to be extended on a two-wire or four-wire basis.
    (3)	Number of voice-frequency ringers required and their proposed location.
    (4)	If system is to be used for transmission of voice-frequency carrier telegraph, state number of telegraph channels required in each direction.
    f.	Voice-frequency Circuit Terminating or Carrier Transfer Points. When line terminating and carrier transfer equipment is required, supply the following information:
    (1)	Number and location of transfer points.
    (2)	Whether the voice-frequency circuit terminates or transfers to another line at the transfer point.
    (3)	Whether composite or simplex telegraph circuits terminate or transfer to another line .at the transfer point.
    (4)	Whether the carrier circuit transfers to another line at the transfer point.
    (5)	Indicate which pairs are physical and which are phantomed.
    (6)	If voice-frequency ringers are required on
    the voice-frequency circuits, give the number of ringers required.
    g.	Availability of Power. (1) Estimate whether the available power source will carry the additional load required by the type H carrier systems.
    (2)	Give voltage and frequency of power sources available at terminals and possible repeater points. Include capacity of generators.
    14.	Open-wire Lines
    The characteristics of open-wire lines vary widely, depending upon the size and type of wire, spacing of wires on the crossarm, and the type of transposition system used. Since it is physically impossible to present data for all types of lines which may be encountered, data given in this manual is for lines constructed in accordance with TM 11-2253. Such lines are designed to carry normally two 88-inch crossarms, each with four pairs of copper or copper-steel wire and with a spacing of 8 inches between the wires of the pairs and 16 inches between pairs, which are suitable for carrier operation. The distance between poles will usually be approximately 150 feet.
    a.	Attenuation. The attenuation of open-wire pairs increases rapidly with frequency, so that losses in the carrier-frequency range usually will be appreciably greater than losses at voice frequencies. The attenuation of open-wire lines of the type described above is given for a number of representative frequencies in table II. Data are given both for dry and wet weather. In laying out a type H system, frequencies of 6,000 and 8,000 cycles ordinarily are considered, since these frequencies roughly represent the modulated 1,000-cycle points in the upper and lower transmitted bands, and wet weather values should be used in the calculation.
    Table II. Approximate attenuation of open-wire line facilities
    Description		—	 7 —	Dry	—	Attenuation (db/mi)			Wet	—
    	1 kc	3 kc	6 kc	8 kc	11 kc	1 kc	3 kc	6 kc	8 kc	11 kc
    080 copper-steel (40%)	0.23	0.29	0.30	0.31	0.32	0.25	0.30	0.32	0.34	0.35
    104 do.	0.16	0.20	0.20	0.20	0.20	0.18	0.21	0.22	0.22	0.23
    128 do.	0.12	0.13	0.14	0.14	0.14	0.13	0.14	0.15	0.16	0.16
    080 copper	0.11	0.12	0.13	0.13	0.14	0.13	0.14	0.15	0.15	0.17
    104 do.	0.074	0.077	0.084	0.089	0.099	0.083	0.087	0.096	0.11	0.12
    128 do.	0.052	0.055	0.064	0.071	0.080	0.061	0.064	0.075	0.088	0 10
    165 do.	0.034	0.038	0.051	0.056	0.064	0.042	0.047	0.060	0.072	0.083
    19
    b.	Impedance. The characteristic impedance of open-wire pairs in the type H frequency range is about 550 to 650 ohms, and is of approximately constant value. Type H carrier equipment on the line side has an impedance of approximately 600 ohms and therefore a satisfactory impedance match is obtained.
    15.	Intermediate and Entrance Cables
    a.	The characteristic impedance of nonloaded cable is much lower than that of open-wire pairs in the type H frequency range. The characteristic impedance of the more commonly used gauges of nonloaded paper-insulated cable is approximately 120 to 140 ohms. Occasionally short lengths of intermediate or entrance cable may be required for lead-ins to offices or for spanning rivers, etc. The large difference between the impedance of the open-wire pairs (approximately 600 ohms) and of the nonloaded cable (approximately 130 ohms) will result in reflections at junction points. Reflections will also occur between the carrier equipment (approximately 600-ohm impedance) and the nonloaded cable. These reflections appear as far-end crosstalk between systems working on different pairs, and the amount of crosstalk will govern the amount of cable which can be tolerated.
    b.	Figure 17 shows the losses which will be obtained by introducing short lengths of nonloaded paper-insulated cable, having a capacitance of about 0.062 microfarads per mile, in a 600-ohm open-wire line. The mileage shown is that of the length of cable inserted. The losses shown include both the cable attenuation losses and the reflection losses at each end. Where several short pieces of cable are used with only a small amount of open-wire between them, the losses per length of cable may be somewhat less than the values shown in the curves. If rubber-insulated cable is used, greater losses will be obtained.
    c.	On lines where only one carrier system is to be operated, there will be no crosstalk problem, and the length of intermediate or entrance cable which can be tolerated is determined largely by the overall transmission loss. On lines where two or more carrier systems are to be operated, the amount of crosstalk which can be tolerated will limit the length of intermediate or entrance cable. The length of nonloaded, paper-insulated cable, having a capacitance of 0.062 microfarads per mile, should be limited to about 700 feet per repeater section. If cable with higher capacitance is used, the permissible length is reduced accordingly.
    I2t   j.    |—।
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    5	-0.5DBMU}	_0 WEF	''	L-»-0DBM
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    “■	hDRM -l-i	!	5 SOB
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    LOOP GAIN 16-5.5= I0 5DB k—--------------
    LOOP GAIN
    16.5 + 275 = 4 4. ODB
    75 Ml ---------------------------------
    LOOP GAIN
    16 + 5.5 = 21 .5DB ------------
    DISTANCE (MILES)
    Figure 18. Typical transmission diagram.
    n mm
    23
    where the power is amplified 16.5 db by the repeater to —1-16 dbm. Between the repeater and the East terminal there is a line loss of 27.5 db (125 miles at 0.22 db loss per mile), which produces an input power of —11.5 dbm ( + 16 dbm minus 27.5 db equals —11.5 dbm) at the East terminal where the power is amplified 5.5 db to bring it to the desired —6 dbm level (—11.5 dbm plus 5.5 db equals —6 dbm). In the East-to-West direction, the input power is raised from 0 dbm to + 16 dbm at the East terminal, is attenuated 27.5 db in the line, and enters the repeater at —11.5 dbm. Here it is raised 27.5 db to +16 dbm, is attenuated 16.5 db in the line, and enters the West terminal at —0.5 dbm. In the West terminal the input power is attenuated 5.5 db to the desired —6 dbm level.
    c. The loop gains can now be obtained from the transmission diagram by adding the gains and losses for each terminal and repeater in each direction of transmission. Thus the loop gain for the West terminal is the difference between 16 db and 5.5 db, or 10.5 db. (The 5.5 db is subtracted since the signal was attenuated at the West terminal.) For the repeater the loop gain is the sum of 16.5 and 27.5 db, or 44.0 db. For the East terminal the loop gain is the sum of 16 db and 5.5 db, or 21.5 db. These loop gains are within the required limits of 26 db for a terminal and 45 db for a repeater.
    19.	Transmission Measurement
    a.	When the equipment is placed in operation, the losses and gains of all components of the circuit and the over-all circuit net loss should be measured to determine the actual working conditions. An oscillator and a transmission measuring set may be used for this purpose. Usually a test power is applied to the input of the circuit to be measured, and then the output of the circuit is measured. It will generally be found that these measurements differ from the computed losses and gains. The transmission diagram and the equipment adjustments must then be changed accordingly. If an oscillator and a transmission measuring set are not available, the over-all circuit operation should be checked by conversing over the circuit and comparing its performance with other circuits.
    b.	The frequency of the test power used depends upon the circuit being measured. The loss of a line section is measured by using a frequency within the carrier range, but the over-all, terminal-to-ter-minal, loss is measured by using a frequency within the voice-frequency range (usually 1,000 cycles). Terminal gains are measured by applying voice-frequency test powers at the switchboard side and car
    rier-frequency test powers at the line side. Repeater gains are measured by applying carrier-frequency test powers. It is also important that the test power levels used correspond to the actual working levels of the circuits being measured.
    c.	When connected to a switchboard on a two-wire basis, the test power input to the carrier system from the switchboard is 0 dbm (assuming no voicefrequency extension) and the test power delivered to the switchboard normally is adjusted to —6 dbm as measured at the two-wire side of the carrier terminal. When connected in this manner the 1,000-cycle net loss of the circuit is 6 db. When the switchboard side of the terminal is connected on a four-wire basis the incoming voice-frequency testing power from the switchboard side is +4 dbm and the receiving circuit is adjusted to deliver +4 dbm to the switchboard side.
    20.	Coordination
    a- If type C carrier or another type H system is used on another pair of the same open-wire line the systems must be coordinated. Such coordination has two main factors, power output and direction of transmission.
    (1)	All systems to be coordinated should be laid out in such manner that the power level at a given frequency at a given point in the line will be approximately equal for all systems. In any given location where type H terminals or repeaters of different systems are installed, there should be no more than 6 db difference in power output. (The use of two type H systems on adjacent pairs or on another pair in the same phantom group is not recommended. However, if two such systems are installed, the differences in power levels should be reduced to a minimum.) In all locations where type H and type C carrier equipment are installed, there should be no more than 6 db difference in output levels between the type H carrier high group of frequencies and the 8-kilocycle point in the type C carrier low group of frequencies.
    (2)	Frequencies in the same range should be transmitted in the same direction. For instance, if two type H systems are to be coordinated, each system should transmit its 7.4- to 10.1-kilocycle band in the East-to-West direction and its 4.1 to 6.9-kilocycle band in the West-to-East direction. If a type C system and a type H system are to be coordinated, the East-to-West 6.5- to 15.6-kilocycle band of the type C carrier and the East-to-West 7.4- to 10.1-kilocycle band of the type H carrier should be transmitted in the same direction because the two bands contain some of the same frequencies. The dissimilar type
    24
    C and type H carrier bands will then be transmitted in the West-to-East direction.
    b. Type C carrier cannot be superposed on the same pair on which a type H carrier system is superposed because of overlapping of frequencies. The
    overlapping of frequency bands is shown in figure 19. The lower side band (4.1 to 6.9 kilocycles) of the H carrier system is shown as the W to E block, and the upper side band (7.4 to 10.1 kilocycles) as the E to W block.
    type	---—r-------------1------------1-----------]
    OF	ARROWS DENOTE CARRIER
    SYSTEM	, FREQUENCIES ।
    | EAST TO WEST j WEST TO EAST
    VOICE
    cs : I :r~3~~l:r~~5~l ir~T~l IT-)! [~i~|! mi
    6-3 9A	12.9	|	| 20.7	244	28.4
    cu =□	|T~I ;r~r~|	i|Tj ![tj
    6.3 7|5	9.4	12.9	177	21.4	25.4
    H	|	| W TO E | j |E TO W
    ____________1_E_J___________________	._____________L___
    0	5	10	15	20	25	30
    FREQUENCY IN KILOCYCLES PER SECOND	TL 51557
    Figure 19. Frequency allocation of carrier systems.
    21.	Radio Link Lay-out
    a.	General. The radio circuit which is to be used as a link between two type H carrier terminals must be a high-fidelity, continuous two-way transmission type, able to handle a reasonably Hat frequency band extending to at least 10 kilocycles. The transmitting and receiving radio equipment must be terminated separately and must be arranged to have an impedance of approximately 600 ohms where connection is made to the carrier line filters. The carrier equipment may be located with the radio equipment, or may be separated physically and connected with short open-wire lines or cable circuits, provided satisfactory crosstalk performance can be obtained. Ordinarily, of the three channels available when type H carrier is superposed on a radio link, the two carrier channels will be used for telephone and the radio (voice) circuit for voice-frequency carrier telegraph. No volume limiters are required on the type El telephone channels. The radio circuit, through the low-pass filters of the carrier line panel, connects to the voice-frequency carrier telegraph equipment on a four-wire basis. Either one or both of the type H carrier terminals may be used for voice-frequency carrier telegraph by connecting the switchboard sides of the terminals to the telegraph equipment on a four-wire basis.
    b.	Differences Between Wire and Radio Link. The problems of radio link transmission differ somewhat from the problems of wire transmission. In wire transmission initial amplification is provided by the carrier terminal. In radio link transmission amplification is provided by the radio transmitter. The design of the radio transmitter permits
    much greater amplification than does the design of the carrier terminal, but with this greater capacity of the radio transmitter for amplification there is a correspondingly greater problem of interference between channels. For this reason the signal must enter the radio transmitter at a lower power level than it enters the carrier terminal. The degenerative effect of intermodulation on telegraph signals is greater than on telephone transmission. For this reason, when any of the channels of a radio link with type H carrier superposed are used for telegraph transmission, the input level to the radio transmitter is adjusted to that level which will be most efficient for telegraph transmission.
    c.	Input and Output Power Levels. Definite input and output power levels for telephone and telegraph transmission over a radio link cannot be given since the capability of the radio transmitter and receiver is the governing factor. Proper input and output power levels for satisfactory transmission will have to be determined by trial.
    fl) Transmitting power levels, (a) Voice-frequency power levels for telegraph transmission. When 12 channels are operated on the voice-frequency circuit, the power level per channel should be approximately —11 dbm transmitted to the radio or H carrier equipment. When fewer than 12 channels are used, the power level may be raised accordingly. The power level at the input to the radio transmitter cannot be specified definitely because it will be limited by overloading and intermodulation in the transmitter and thus will depend upon the characteristics of the particular transmitter used. However, the power level into the radio transmitter
    25
    may be controlled sufficiently by adjusting the input potentiometer of the radio transmitter.
    (b) Type H carrier power levels. When the type H channels are used for telephone, the suggested power level from the switchboard is 0 dbm and the suggested level at the line side of the terminal is —10 dbm. When the type H channels are used for telegraph, the power level at the switchboard side should be —11 dbm per channel and the level at the line should be —10 dbm.
    (2)	Receiving power levels. The received power level at the REC LINE of the voice-frequency carrier telegraph terminal should be at least —11 dbm per channel. In adjusting the power level of the radio receiver ouput, the loss in any line between the receiver, carrier terminal, and voice-frequency telegraph equipment must be considered. The output power level from the receiver should be sufficient to overcome any such line loss and reach the telegraph equipment at a minimum of —11 dbm per channel. With the receiver output at this level the input power level at the line side of the carrier terminal will be satisfactory. The desired power level (generally —6 dbm) at the carrier terminal switchboard can then be reached by adjusting the receiving gain to raise the signal to the desired level,
    22. Carrier Terminations and Extensions
    a.	General. Discussions of circuit loss up to this point have considered only the carrier terminal-to-carrier terminal portion of the circuit. When the carrier circuit is terminated at a switchboard adjacent to the carrier terminal, only these terminal-to-ter-minal considerations need be considered. However, if the carrier circuit is extended, either on a two-wire or four-wire basis, the over-all circuit (switchboard-to-switchboard) must be considered. Though it is desirable that the extension terminate at no less than a —6-dbm power level, it may often be necessary to accept a less favorable power level than —6 dbm at the terminating switchboard. The amount of loss greater than 6 db which can be tolerated will de
    pend on transmission conditions. Distinction is made in this text between extension on a two-wire or four-wire basis and termination on a two-wire or four-wire basis. Both refer to arrangements on the switchboard side of the carrier terminal, but termination refers to actual connections and switch settings at the carrier terminal whereas extension refers to the facilities by which the circuit is extended. For example, if the type H system connects to a voice-frequency repeater adjacent to the terminal, the type H carrier terminal would be terminated on a four-wire basis for connection to one side of the repeater, and the circuit beyond the repeater would be extended either on a two-wire or a four-wire basis, depending on whether the extension facility were an open-wire pair or two cable pairs. The power levels and circuit losses indicated in the following paragraphs are examples of conditions most favorable to good transmission, but their use as examples does not mean that others may not be used with good results.
    b.	Terminations. A type H carrier terminal may be terminated on the switchboard side on a two-wire or a four-wire basis. When the terminal is terminated on a two-wire basis the voice currents pass through a hybrid coil circuit. When the carrier terminates on a four-wire basis, connection is made directly to the input and output of the associated equipment, thus making it unnecessary to use hybrid coil circuits. When talking circuits derived from a carrier system connect to a switchboard in the same office in which the carrier terminal is located, the carrier terminal will be connected to the switchboard on a two-wire basis (fig. 20).
    (1) Receiving. The power level ordinarily will be adjusted to —6 dbm at the carrier receiving terminal and will be extended to the switchboard at the —6 dbm level.
    (2) Outgoing. The power level transmitted from the switchboard to the carrier terminal will be about 0 dbm. (The carrier terminal equipment will modulate and amplify the signal for transmission over the line.)
    0	+16	-G
    DBM	DBM	DBM
    s --------------- H _________________Z~| H rz__________________ H _____________________ c
    _______________ CARR	- CARR -	CARR	3 TERM.	_] SYSTEM [_	TERM.	8
    *6	+16	F
    ।	DBM ।	DBM	DBM
    |___ EQUIP LOCATED__________|	|________ EQUIP. LOCATED
    IN SAME OFFICE	IN SAME OFFICE
    n »t»e» Figure 20. Switchboard termination.
    26
    c. Extensions. A type H carrier system may be extended either on a two-wire or a four-wire basis, depending on the facilities used. If extended on an open-wire pair, the type H system is terminated on a two-wire basis. On four-wire cable arrangements the type H system is terminated on a four-wire basis. The amount of loss in the extension and the amount of gain available at the carrier terminal will determine the design of the extension circuit. If there is sufficient receiving gain available at the carrier terminal so that the loss in the extension circuit can be overcome to obtain a satisfactory power level at the extension switchboard, the circuit may be designed without a repeater. Two of the factors which will govern the gain available for the extension circuit are the maximum permissible transmitting gain which a terminal can provide and the amount of gain remaining in the terminal after the carrier circuit power levels are met.
    (1) Maximum permissible transmitting gain. The maximum terminal loop gain is +26 db and the most favorable transmitting level is +16 dbm. To these limitations must be added a limitation on the maximum amount of transmitting gain which a terminal can provide. This maximum transmitting gain for a type H carrier terminal is +20 db. That is, if a signal is to be transmitted at +16 dbm, it can enter the 2W HYB jacks of the terminal at a power level no lower than —4 dbm (if it enters the carrier terminal at less than —4 dbm, it will have to be transmitted at a power level lower than the desired +16 dbm). In using the maximum transmitting gain of +20 db it must be remembered that this will leave only 6 db of the 26-db loop gain available for amplification in the receiving direction.
    (2) Amount of gain remaining in terminal. If the carrier circuit has been so designed that there is gain available in the carrier terminal, this gain may be utilized to obtain a more favorable power level at the extension termination. A circuit which terminates at —6 dbm at the carrier terminal and which has a 4.5-db gain available before the 26-db terminal loop gain is exceeded is shown in figure 18. The East terminal loop gain is 21.5 db, leaving 4.5 db available which may be applied to the extension circuit. This should be divided to give a gain of approximately 2 db in each direction for the extension circuit. Instead of leaving the carrier terminal at —6 dbm, the 2-db gain will raise the power level toward the switchboard to —4 dbm. If the extension circuit has a loss of 2 db the signal will arrive at the switchboard at the desired —6 dbm level. In the other direction of transmission, the signal transmitted from the extension switchboard at 0 dbm will lose 2 db
    between the terminating switchboard and the carrier terminal, arriving at —2 dbm. A transmitting gain of 18 db will be required to raise it to a power level of +16 dbm for transmission over the line. The loop gain at the carrier East terminal now totals 25.5 db (an increase of +2 db receiving and +2 db transmitting).
    23.	Extensions to Voice-frequency Telephone Repeaters and Other Carrier Telephone Systems
    a.	Four-wire Basis (fig. 21). All extensions to voice-frequency telephone repeater systems and other carrier telephone systems should be made on a four-wire basis to reduce input and output equipment losses and singing paths. T he type H carrier system is laid out as though it would be terminated on a two-wire basis and have a circuit net loss of 6 db. It is assumed that each system connected in tandem can be operated with a 6-db circuit loss if terminated on a two-wire basis. If greater losses are encountered, the circuit must be considered from switchboard-to-switchboard, and deviations made in the individual systems involved as required. After the type H carrier system is laid out on a two-wire, 6-db loss basis, it is arranged for four-wire termination at the point of connection to the other system. The transmitting path of the type H system is connected to the receiving path of the other system, and the other system is adjusted to transmit a power level of +4 dbm to the type H system. The receiving path of the type H carrier system is connected to the transmitting path of the other system, and the type H system is adjusted to transmit a power level of +4 dbm to the other system. If the terminal equipment of both systems is not located in the same office and the interconnection is made with four-wire cable facilities, the connections are arranged as described above, but the loss contributed by the cable facilities must be considered. The receiving and transmitting equipment must be readjusted to compensate for this loss and to compensate for deviations from the nominal 4-db levels at the input to the transmitting path of each system. The desired circuit net loss from switchboard-to-switchboard is established by adjustment of the receiving equipment of the system to which the two-wire connection to the switchboard is made.
    b.	Two-wire Basis. Although two-wire interconnections between two systems are not recommended and should be avoided, it may at times be necessary to use them because the connecting equipment is not arranged for four-wire termination or the equipments are separated and are to be interconnected with open-wire facilities. However, the num
    ber of singing paths and the input and output equipment losses are increased since hybrid coil circuits must be used at the two-wire termination of each system. Furthermore, singing problems may be encountered in the type H system since the compromise balancing network for the type H carrier hybrid coil is designed to balance a switchboard termination. When two systems are interconnected on a two-wire basis, the over-all (switchboard-to-switchboard) loss will be the algebraic sum of the losses of the two systems. For example, if the over-all loss in one carrier system is —6 db and the over-all loss in the second carrier system is —6 db, the received power level at each switchboard will be —12 dbm. If the —12 dbm level at the switchboards cannot be tolerated, it will be necessary to raise the power levels in each carrier section. However, the highest overall system net loss at which the type H carrier system should be operated is —3 dbm. Since the impedance of the interconnecting circuit and the circuit net losses of each system are the determining factors in determining the workable power levels at the point of interconnection, these levels will vary with individual cases and must finally be determined by actual trial.
    24.	Extensions to Voice-frequency Carrier Telegraph Systems
    A type H channel may be used to provide the transmission path for a voice-frequency carrier telegraph
    system. The interconnection should be made on a four-wire basis.
    a.	Packaged Equipment (fig. 22). Frequency characteristics of the type H carrier band may prevent full use of the 6 or 12 two-way telegraph channels provided by voice-frequency carrier telegraph packaged equipment. The number of voice-frequency telegraph channels which can be operated over a type H carrier system will depend on the type H frequency characteristics, the net loss of the intervening open-wire line, the stability of the line, and the presence of type H carrier repeaters (repeaters tend to degrade carrier telegraph transmission). Even under favorable conditions it will seldom be possible to use a low-frequency telegraph channel of about 425 cycles. Channels in the middle of the voice-frequencj band will be the best, degrading in quality as the lower and upper limits of the frequency band are reached. The type H carrier system is lined up in the usual manner for four-wire termination. The transmitting path of the type H carrier terminal is connected to the send path of the telegraph terminal, and the receiving path of the type H carrier terminal is connected to the receive path of the telegraph terminal. The nominal telegraph power output level (one channel marking) used is —11 dbm, although it may be raised slightly if a reduced number of channels (less than 12) is used and satisfactory operation is not obtained with the nominal level.
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    +4	+16	+4
    DBM	DBM	DBM
    ANOTHER --------- ----------------------------------------—----- ANOTHER
    CARR ----------- H	H	H ---------- CARR
    TERM OR	CARR	— CARR ---- CARR	TERM. OR
    V-F TP --------- TERM ------- SYSTEM	TERM	v'r TP
    REPTR ---------- ---------------------------------------------- REPTR
    +4	+16	"*~+4
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    |EQUIP LOCATED|	|EQUIP LOCATED|
    IN SAME OFFICE	IN SAME OFFICE
    TL 51269
    Figure 21. Four-wire extension to other systems.
    28
    b.	Tactical Carrier Telegraph Equipment. Some models of this equipment are not arranged for four-wire connections and the connection to the type H carrier systems must be made on a two-wire basis. In this case the type H carrier system is set up to have a 6-db circuit net loss. Later models of
    this equipment are arranged for two- or four-wire connections. The four-wire connection is recommended, and in this case the type H system is arranged as described in a above. If desired, a two-wire connection may be made as described for the earlier models.
    Section III. UNPACKING, SETTING UP, AND REPACKING
    25.	Location of Equipment
    The building in which this equipment is installed should be dry, well ventilated, kept at reasonably constant temperature, and have solid flooring. Apparatus cabinets or 19-inch relay racks for mounting the type H carrier panels must be provided separately. If the equipment is installed with other items of packaged equipment, an office layout will have been prepared, as described in TM 11-2022. The main requirements for locating the equipment in a building are that the wiring be as short as possible, and that there be ample space for opening cabinet doors and working on the equipment. Whenever possible associated equipment panels should be mounted in the same cabinet with the type H carrier panels, and associated cabinets should be adjacent. This is extremely important for phantom group operation where it is desirable to keep the wiring of the two side circuits the same length. Since carrier frequencies are used, the type H carrier equipment should be located as close as possible to the openwire or entrance cable terminal.
    26.	Unpacking Instructions
    The H carrier terminal panel, repeater panel, and line panel are individually packed in waterproof, moistureproof, and vaporproof packing cases. Spare parts and installing materials are also packed within the packing cases. Physical dimensions for each of the units packed for export are shown in table TV.
    Tabic IV. Packing data
    Panel	Dimensions (in.)	Weight (lb.)	Shipping space (cu. ft.)
    Carrier Terminal OA-13/FC	25 x 20 x 18	125	6.0
    Carrier Repeater OA-IO/FC	24 x 18x 14	70	4.5
    Carrier Filler OF-36/FC	24 x 18x 12	40	2.9
    a.	Method of Packing (figs. 23, 24, and 25). Each of the panels is packed in approximately the same manner. Immediately inside the packing case (1) a waterproof bag (2), sealed with a rubber
    cement, provides protection against water damage to the equipment. Next an outer carton (3) of fiberboard acts to cushion the equipment from severe shocks. Inside this carton a paper foil barrier (4) affords the equipment protection from damage by moisture or vapor, which would cause rust and corrosion, The air in this barrier is evacuated before sealing. The inner carton (5) acts to further cushion the equipment from severe shocks, and both the inner and outer cartons protect the sealed moistureproof and vaporproof barrier from damage by sharp corners on the equipment or packing case.
    Note. Item (S) in the terminal packing is made of wood, and is called a box, while in the repeater and line panel packings it is made of fiberboard.
    Various inner details of fiber (6) protect the equipment from rough handling, and hold loose parts securely in place during shipment. The equipment (7) is held rigidly in place within the packing case by a wooden rack unit (8). Spare parts, installing materials, and bags of silica gel (9) are firmly packed around the equipment; spare parts for the line panel are inclosed in a separate carton. The silica gel provides the equipment with additional moisture protection, acting as an absorbent for any moisture which may enter the barrier.
    b.	Unpacking. Use care in unpacking the equipment, so that the packing materials may be re-used if the equipment is to be reshipped at a later date. Using the packing illustrations as a guide, unpack the equipment in the most practicable manner. The seams on the waterproof bag and the barrier can be broken by prying or pulling apart with the hands. These packing materials can also be opened by slitting along the top seam with a knife. This will allow their re-use after repair with tape. Discard the silica gel, a$ its absorbent quality deteriorates with age. When unpacking the spare parts and installing materials check them against the applicable list included with the equipment. After each unit is unpacked, place its packing materials within the packing case, nail the cover on again, and store the case in a convenient location.
    29
    8-RACK UNIT
    4-MOISTUREPROOF AND VAPORPROOFI BARRIER
    6- LOWERL CAP
    6- UPPER: CAP
    l-PACKING CASE COVER
    2-WATERPROOF1 BAG
    TL5I57I
    9-SPARE PARTS AND BAGS OF SILICA GEL
    OUTER CARTON
    7-TERMINAL PANEL
    5-*-INNER BOX
    Figure 23. Packing details, terminal panel.
    5- COVER FOR INNER BOX
    l-PACKING CASE
    30
    6-LINER
    4-MOISTUREPROOF AND VAPORPROOF BARRIER
    5—INNER CARTON
    7- REPEATER PANEL
    I- PACKING CASE
    l-PACKING CASE COVER
    TL5I572
    8-RACK UNIT
    3-OUTER
    CARTON
    2-WATERPROOF BAG
    Figure 24. Packing details, repeater panel.
    — 6-PADDING
    9-SPARE PARTS AND BAGS OF SILICA GEL AROUND PANEL
    31
    -	X?\ ______ I - PAC KIN b
    \>?\——— CASE C0VER
    9-SPARE PARTS ______
    CARTON	I Ax
    4-MOISTUREPROOF
    ANO VAPORPROOF-------*~X X<	UR
    BARRIER ^-^\'\	^TX****’3*^ IX |
    Xx \ \^	J 7 VZ 6-FIBER DETAIL
    <^---B	------- (TOP *ND
    W__	BOTTOM)
    7-LINE	-----------“8-RACK UNIT
    PANEL	1__^>XAlF
    I \	-------------5-INN ER CARTON
    9-BAGS OF________ | \ Wq*S^7
    SILICA GEL	X V\ I	X^-^Xs.
    XX.	----------3-OUTER CARTON
    2-WATERPROOF________2.‘ \	J
    BAG	"	--~
    I- P A C KI N G_JI
    CASE	X
    T L 515 7 3
    Figure 25. Packing details, line panel.
    27. Setting-up Procedure
    Mount the panels in an apparatus cabinet together with associated panel equipment. If no apparatus cabinet is available, the panels may be mounted on any standard 19-inch relay rack or wooden timbers ^similarly spaced and fastened rigidly to the floor and , ceiling. Mount the terminal panel above its associated line panel (fig. 26). Note that a terminal installation requires 9 mounting plate spaces, 7 for the terminal panel and 2 for the line panel. Mount the repeater panel between its associated line panels (fig. 27). Note that a repeater installation also requires 9 mounting plate spaces, 5 for the repeater panel, and 2 for each of the line panels. At a radio link installation, mount the 2 terminal panels together between the 2 line panels. Note that this installation requires 18 mounting plate spaces, 7 for each terminal panel and 2 for each line panel. Screws for mounting the panels are not furnished with the panels.
    23.	Repacking Instructions
    a.	Disconnect all connecting wires and the plug to the external power supply.
    b.	Remove each panel from the cabinet or relay rack and place it in its rack unit, securing it firmly with the wooden details.
    c.	Slide the rack unit into the inner carton.
    d.	Collect all spare parts and installing materials and pack securely around the panel.
    e.	Seal the inner carton with gummed tape, replace the outer carton, and seal it with tape also.
    f.	Slip the waterproof bag over the outer carton and seal it with tape.
    g.	Place the entire unit in the packing case, put the remaining packing materials on top, and nail the cover on securely.
    h.	If the original packing materials have been discarded, construct a rack unit which will hold the panel securely, and place this unit within a suitable crate together with the spare parts and installing materials.
    32
    Figure 26. Terminal installation.
    33
    Figure 27. Repeater installation.
    PART TWO
    OPERATING INSTRUCTIONS
    Note. For information on destroying this equipment to prevent enemy use, see the destruction notice at the front of this manual.
    Section IV. EQUIPMENT CONNECTIONS AND PRELIMINARY ADJUSTMENTS
    29.	Connections and Adjustments
    The equipment connections and adjustments contained in this section provide satisfactory operation in a minimum of time and are to be followed whenever placing the equipment in service. However, to obtain optimum performance, the detailed tests, adjustments, and line-up procedures contained in section V should be performed when time permits.
    a.	Terminal, Wire Operation. The connections, connecting arrangements, and adjustments required at a terminal for wire operation are listed below with paragraph references. The tests and adjustments should be performed in the order given.
    Terminal connections and adjustments required:
    Ground connections (pars. 30a through dj.
    Power connections (par. 31).
    Voltage adjustments (par. 32).
    Vacuum tube checks (par. 33).
    Line switch setting (par. 34a and &).
    Equipment switch setting (par. 35).
    Gain adjustments (par. 36a and b).
    Connecting arrangements (par. 37).
    Terminating connections (par. 38).
    External balancing network connections, if required (par. 39).
    Line connections (par. 40a).
    b.	Repeater, Wire Operation. The connections, connecting arrangements, and adjustments required at a repeater for wire operation are listed below with paragraph references. The tests and adjustments should be performed in the order given.
    Repeater connections and adjustments required:
    Ground connections (par. 30a through c and a).
    Power connections (par. 31).
    Voltage adjustments (par. 32).
    Vacuum tube checks (par. 33).
    Gain adjustments (par. 36a and c).
    Connecting arrangements (par. 37).
    Line connections (par. 40a).
    c.	Radio Link Operation. The connections, connecting arrangements, and adjustments required tor radio link operation are listed below with paragraph references. The tests and adjustments should be performed in the order given.
    Connections and adjustments required for radio link operation:
    Ground connections (par. 30a through c and /).
    Power connections (par. 31).
    Voltage adjustments (par. 32).
    Vacuum tube checks (par. 33).
    Line switch setting (par. 34c).
    Equipment switch setting (par. 35).
    Gain adjustments (par. 53).
    Connecting arrangements (par. 37).
    Terminating connections (par. 38).
    External balancing network connections, if required (par. 39).
    Line connections (par. 40Z?).
    d.	Carrier Transfer Equipment. The connections required at a carrier transfer point are given in paragraph 41.
    c.	Check of System Performance. After all connections and adjustments have been made, check the system to insure satisfactory performance (par. 42)V ,
    f.	1 esting Equipment. No equipment for testing is provided as part of type H carrier equipment. The following equipment, usually available at a central office or a voice-frequency telephone repeater installation, should be used for installation testing purposes.
    34
    35
    Nomenclature	Signal Corps stock No.	Mfr’s. No.	Description	Usage
    Multimeter TS-380/U.	3F7127	WECo D-166852.	Volt-ohm-milliammeter.	Voltage, current, and resistance measurements.
    Tube Tester 1-171.	3F5681	Hickok model 560 (SPL).	Vacuum tube test set.	Test vacuum tubes.
    30. Ground Connections
    a.	General. A common ground connection is provided in each cabinet and on each relay rack used to mount type H carrier equipment. Connection is made from the office grounding system to these common grounds. In turn, connections are made from this ground connection to each panel.
    b.	Office Grounds. (1) All office equipment must be connected to a common grounding system. A buried metallic water-supply system is preferable, but buried gas pipes or other metallic structures may be used. In either case, the neutral wire of the power distribution circuit should use the same ground.
    (2) When a suitable existing ground system is not available, driven ground rods are used. Ground rods are not supplied as part of the type H carrier equipment. Five ground rods, at least 3 feet in length, should be used. Set the ground rods a minimum of 6 feet apart. Before installing the ground rods, clean the connecting surfaces of the rods and the wire to be used. If possible solder the joints. Bond the ground rods to the ground used for the neutral of the power system with 6- or 8-gauge copper wire. When rods are located in the basement of a building, drive them to within 6 inches of the floor level. Place the rods at least 2 feet from any wall. When ground rods are located outdoors, set them as near to the building as practicable but in no event closer than 2 feet. To set ground rods outdoors, dig a trench and drive the rods below ground level. After the connections are made, cover the trench with boards to permit ready periodic inspection of the ground leads. See TM 11-755 for more detailed instructions on the establishment of an office ground.
    c.	Grounding of Cabinets, Terminal or Repeater. Run a 6- or 8-gauge copper wire from the common office ground to the nearest cabinet, and from that point to the other cabinets. Connections are made to lugs in each cabinet.
    d.	Grounding of Terminal Panels, Wire Operation. (1) Clean one end of a 6-foot length of single-conductor copper wire and solder it to terminal 16 of terminal strip A on the terminal panel.
    Terminal strip A is located on the lower right rear of the terminal panel (fig. 28).
    (2)	Run the wire along the side of the cabinet to the line panel and loop the wire so as to make connection to terminal 8 of terminal strip A on the line panel. Terminal strip A is located on the rear of the line panel (fig. 29).
    (3)	Solder the loop connection made in (2) above.
    (4)	Run the wire to the cabinet ground connection, and solder.
    (5)	Tie the ground wire to the cabinet supports.
    e.	Grounding of Repeater Panels. (1) Clean one end of a 6-foot length of single-conductor copper wire and solder it to terminal 8 of terminal strip A on the upper line panel (fig. 29).
    (2)	Run the wire along the side of the cabinet to the repeater panel and loop the wire so as to make connection to terminal 8 of terminal strip A on the repeater panel (fig. 30).
    (3)	Solder the loop connection made in (2) above.
    (4)	Continue running the wire along the side of the bay to the lower line panel and loop the wire so as to make connection to terminal 8 of terminal strip A on the lower line panel (fig. 29).
    (5)	Solder the loop connection made in (4) above.
    (6)	Run the wire to the cabinet ground connection, and solder.
    (7)	Tie the ground wire to the cabinet supports.
    f.	Grounding of Terminal Panels, Radio Link. (1) Clean one end of a 6-foot length of single-conductor copper wire and solder it to terminal 8 of terminal strip A on the upper line panel. Terminal strip A is located on the rear of the line panel (fig. 29).
    (2) Run the wire along the side of the bay to the upper terminal panel and loop the wire so as to make connection to terminal 16 of terminal strip A on the terminal panel. Terminal strip A is located on the lower right rear of the terminal panel (fig. 28).
    (3) Solder the loop connection made in (2) above.	*
    36

    ^MOD OUTFr
    TERM. STRIP
    TUBE
    X662I 7A-I
    MFP9-44
    RETARDATION ’ COIL P ***,
    FIBER
    fs-RKIN
    16
    (TRANSFORMER PWR
    TERM.STRIP ’'TERM. STRIP B
    ■A	,	,	, lTL5l562T&
    0 * $ *
    ADJUSTMENT
    Figure 28. Terminal panel, rear view.
    Figure 29, Line panel, rear view.
    37
    Z ' ; '•..	'	'	■ -.STRIP .7'
    '	■ ■ ..	’ - '■■'	■'.■/■	G a	■ '
    ••/■	" ""HEB © I©
    Ac •<,'>'>■ ■ ■■■ FJfcR*	xzi	’	... .^JSMWpgAa	|<
    '•'	iMmr £*........0i^flwbdb L •
    ,-t-	—r -—«■	-	' 	f r 9UI	C	^r- ■/- - v - -	m -.A.
    •	-'^\	X 66 217R -1	: •
    TfX Xu^^n^BKSH ' Pr^	J? MFP^u b
    ® e L _
    itransformer	, ?'	• fRLfV
    Figure 30. Repeater panel, rear view.
    (4)	Repeat the procedure given in (2) and (3) above for the lower terminal panel.
    (5)	Continue running the wire along the side of the bay to the lower line panel and loop the wire so as to make connection to terminal 8 of terminal strip A on the lower line panel (fig. 29).
    (6)	Solder the loop connection made in (5) above.
    (7)	Run the wire to the cabinet ground connection, and solder.
    (8)	Tie the ground wire to the cabinet supports.
    31.	Power Connections
    a.	General. (1) Two methods are used for supplying 105- to 125-volt, 50- or 60-cycle alternating current to the cabinets. Earlier model cabinets used the direct-wiring method while later model cabinets use the cord and plug method for connection to the a-c power. With either method, it is necessary to determine which wire of the office supply is the grounded or identified lead. Normally, the white or identified lead is the grounded power lead and the black lead is the ungrounded or live power lead. The grounded lead may be determined by measuring the voltage between each wire and ground.
    (2)	The terminal and repeater panels are provided with power cords and plugs that are plugged into convenience outlets. These convenience out
    lets, which are contained on the plug-in strip at the rear of the 3-foot 6-inch and 7-foot cabinets, are protected with a fuse located at the bottom of the cabinet. Appliances should not be connected to the plug-in strip since a blown fuse due to a faulty appliance will put the terminal or repeater out of service. No plug-in strip is provided on the 2-foot 4-inch cabinets; instead the power cord plugs of the terminal or repeater panels are inserted into one of the UT & T outlets. Since the UT & T outlets are not fused, appliances should not be plugged into these outlets.
    b.	Connecting Cabinets, Cord and Plug Arrangement. (1) Run one pair of power leads from the office distribution panel to the near end of the cabinet line-up.
    (2	) Terminate the pair or power leads at the cabinet, by connecting the short length of power cord attached to the polarized twist-lock connector body (receptacle) furnished, in the following manner:
    (a) Splice the grounded side of a grounded power supply, or the identified side of a nongrounded power supply, to the identified lead of the polarized connector body.
    (&) Splice the other power lead to the remaining lead of the polarized connector body.
    (c) Solder and properly tape the splices.
    (3)	Run the power cord associated with the first
    38
    cabinet of a line-up along the cable run to the polarized connector body and insert the polarized plug into the polarized connector. Lock the plug by turning it to the right.
    (4)	Run the power cord associated with the second cabinet along the cable run to the first cabinet and insert the power cord plug into one of the PWR receptacles of the first cabinet. Lock the plug by turning it to the extreme right. This is important because accidental removal of the plug disconnects power from all succeeding cabinets.
    (5)	Repeat the procedure given in (4) above for all other cabinets in the line-up. Accidental removal of a plug will cut off the power supply to all succeeding cabinets in the line-up.
    c. Connecting Cabinets, Direct Wiring Arrangement. (1) Run one pair of power leads from the office distribution panel to the near end of the line-up; continue running the wires in the cable run under the cabinets to the far end of the line-up. Keep the power leads as far as possible from other wiring in the cable run.
    (2)	After removing the cover from (he front of the outlet box . assembly of the first cabinet in the line-up, splice the leads in the outlet box to a short length of power wire. Splice the identified leads together and splice the black leads together.
    (3)	Remove a knock-out from the bottom of the outlet box of the first cabinet of the line-up and pull the short length of power wire through the knockout opening.
    (4)	Splice the short length of wire to the power leads in the cable run, connecting the identified wire to the grounded power lead of a grounded power system or to the identified lead of a nongrounded power system. Connect the black leads together.
    (5)	Repeat the procedure given in (2), (3), and (4) above for each cabinet to which power is required.
    (6)	Solder and properly tape all splices; replace the outlet box covers.
    d.	Fuse Checks. Check to see that the required 10-ampere fuses are installed in fuse receptacles of the 3-foot 6-inch cabinet or the 7-foot cabinet. If fuses are not supplied, unscrew the fuse holder from each socket, insert a cartridge-type fuse in the open end, and replace the fuse holder in the socket. The small hole in the other end of the fuse holder permits the insertion of a nail, or similar implement, to aid in the removal of a blown fuse.
    e.	Connecting Terminal or Repeater Panels. Insert the power cord plugs of the terminal or repeater panels into the outlets in the plug-in strip at the rear of the 3-foot 6-inch and 7-foot cabinets,
    or into one of the UT & T outlets of a 2-foot 4-inch cabinet. Do not connect appliances to the plug-in strip; appliances such as testing instruments, soldering irons, etc., may be connected to the APPLIANCE outlets of the outlet box. Do not use the spare outlet of the 2-foot 4-inch cabinet for appliances unless absolutely necessary as no fuse is provided in the outlet circuit.
    32.	Voltage Adjustments (figs. 28 and 30)
    Caution: When power is connected, voltages existing on certain terminals of the equipment are sufficiently high to be dangerous. Accordingly, attendants are cautioned against touching any live terminal and any other terminal or ground at the same time. When checking and adjusting the equipment, disconnect the a-c power whenever possible. If it is necessary to turn on the power for the purpose of making measurements, proceed with extreme caution. The type H carrier terminal and repeater are designed to operate from a 50- to 60-cycle, 105- to 125-volt a-c power source. Taps are provided on the primary of power transformer PWR which supplies alternating current to the heaters of the vacuum tubes and the varistor rectifier. At the time of installation the line voltage must be measured, the tap lead of the transformer primary adjusted, if necessary, and the d-c output of the varistor rectifier measured.
    a.	Apparatus Required. Multimeter TS-380/U.
    b.	Adjustment of Power Transformer Primary. (1) Disconnect the power cord plug.
    (2)	Using the 300V a-c scale of the multimeter, measure the a-c supply voltage at the outlet box or plug-in strip.
    (3)	The tap lead on the primary of transformer PWR is connected at the factory to terminal 5. Reconnect the tap lead, if necessary, to meet the line voltage requirements shown below.
    A-c line voltage	Connect tap lead to terminal
    Less than 112	3
    112 to 118	4
    Greater than 118	5*
    Tap lead is connected to this terminal during manufacture.
    (4)	Insert the power cord plug into the convenience outlet.
    c.	Check of Rectifier Output. (1) Allow sufficient time for the tubes to heat.
    (2	) Using the 300V d-c scale of the multimeter, measure the rectifier output voltage between terminal 1 of retardation coil P and ground.
    39
    Requirement: The output voltage should be between 125 and 190 volts.
    (3	) If the requirement given above is not met, see paragraph 46.
    33.	Vacuum Tube Checks
    The terminal and repeater panels are shipped with the vacuum tubes mounted in the sockets. Spare vacuum tubes are provided in a separate container. Check to see that the tubes are seated properly in the sockets. Check the vacuum tubes with a tube tester.
    34.	Line Switch Setting
    The line switch, designated LINE, can be set to any one of four positions: WIRE EAST, WIRE WEST, RADIO TRANS, and RADIO REC (fig. 3). For radio link operation, switch LINE of the upper terminal panel is set to RADIO TRANS while switch LINE of the lower terminal panel is set to RADIO REC. For wire operation, the setting of switch LINE generally is specified. If no specifications are given, the correct switch setting is determined on the basis of the particular operating line conditions. When operating over wire facilities, once the direction of transmission and the position of switch LINE are determined, neither can be changed without interfering with the operation of the other carrier systems on the line.
    a.	When Setting Is Specified, Wire Operation. If an East terminal is specified, set switch LINE to WIRE EAST; if a West terminal is specified, set switch LINE to WIRE WEST.
    b.	When Setting Is Not Specified, Wire Operation. (1) With Another H Carrier System or a C Carrier System on Same Open-Wire Line. Switch LINE must be set so that the direction of transmission of both systems corresponds. Set switch LINE accordingly.
    (2)	With Carrier Systems Other Than H or C Carrier on Same Open-Wire Line. If the other carrier systems have one direction of transmission in the frequency range of 7 to 10 kilocycles, switch LINE must be set so that the East-to-West direction of transmission of the type H carrier system is in the same direction as the 7- to 10-kilocycle band of the other systems. Set switch LINE accordingly. If the other carrier systems do not utilize the frequency range of 7 to 10 kilocycles, follow the procedure given in (3) below.
    (3)	With No Other Carrier System on Same Open-Wire Line. The setting of switch LINE is determined by geographical location. The terminal which is at the north or east end of the system is
    the East terminal; the terminal which is at the south or west end of the system is the West terminal. Set switch LINE accordingly.
    c.	Radio Link Operation. Set switch LINE of the upper terminal panel to RADIO TRANS and set switch LINE of the lower terminal panel to RADIO REC.
    35.	Equipment Switch Setting
    The equipment switch, designated EQ PT, has three switch positions; 2W, 4W TEL, and 4W TLG. The switch is set in accordance with the terminating arrangement. For the procedures given, switch position 4W TLG is not used. It is provided for cases where it is desired to eliminate the 8-db pad from the transmitting path.
    a.	Two-wire Termination. For all conditions where the channel is terminated on a two-wire basis, set switch EQPT to position 2W.
    b.	Four-wire Termination. For all conditions where the channel is terminated on a four-wire basis, set switch EQPT on position 4W TEL.
    36.	Gain Adjustments
    a.	General. (1) The gains of the terminals and repeaters should be adjusted in accordance with the characteristics of the adjacent open-wire line sections. The adjustments given below arc to be performed when the system is first installed. Since these adjustments are based on average line characteristics, optimum performance will not result. When time permits, perform the detailed tests and adjustments given in section V in order to obtain optimum performance.
    (2)	The receiving gain adjustments are given in tables V and VI for a terminal and repeater, respectively. The gain adjustments given in both tables are based on the characteristics of average lines and assume that each line section is composed entirely of the same gauge of copper or copper-clad steel wire. However, if a line section is composed of dififerent gauges of wire, the line facility, so far as the gain adjustments are concerned, may be considered as composed entirely of the most common wire gauge used. Though the settings given in the tables assume dry weather line conditions, the tables may be used when setting up the system during wet weather providing the detailed tests and adjustments given in section V are performed as soon as practicable.
    (3)	These adjustments do not apply for radio link operation. Instead, perform the detailed tests and adjustments given in section V.
    b.	Terminals. (1) Set control TR GAIN to 44.
    40
    (2)	Set control REC GAIN in accordance with table V, observing the limitations given in a(2) above.
    Note. Do not sot control REC GAIN to a position greater than. 44.
    c.	Repeaters. (1) Set control E-W and W-E GAIN in accordance with table VI observing the limitations given in a(2) above.
    (2) Add the numerical value of the settings of controls E-W GAIN and W-E GAIN.
    Requirement: The sum of the E-W GAIN and W-E GAIN settings should not exceed 82.
    (3) If the requirement is not met, reduce the setting of each gain control an equal amount until the requirement is met.
    Table V. REC GAIN Control settings at terminal
    Open-wire facility				REC GAIN setting
    Type	Gauge (mils)	Length of line
    		sectiot	i (miles)
    Copper-steel	080	25	to 35	20
    		35	to 45	22
    		45	to 55	26
    		55	to 65	30
    		65	to 75	32
    		75	to 85	34
    		85	to 95	38
    		95	to 105	42
    Copper-steel	104	25	to 45	18
    		45	to 65	22
    		65	to 85	26
    		85	to 105	30
    		105	to 125	32
    		125	to 145	38
    		145	to 165	42
    Copper-steel	128	30	to 60	16
    		60	to 90	20
    		90	to 120	26
    		120	to 150	30
    		150	to 180	32
    		180	to 210	38
    		210	to 240	42
    Copper	080	25	to 50	16
    		50	to 75	18
    		75	to 100	20
    		100	to 125	26
    		125	to 150	28
    		150	to 175	30
    		175	to 200	34
    		200	to 225	38
    		225	to 250	40
    Copper	104	20	to 50	12
    		50	to 90	16
    		90	to 130	20
    		130	to 170	24
    		170	to 210	26
    		210	to 250	30
    		250	to 290	34
    		290	to 330	36
    		330	to 370	42
    Open-wire facility			REC GAIN setting
    Type	Gauge (mils)	Length of line section (miles)
    Copper	128	25 to 75	14
    		75 to 125	18
    		125 to 175	20
    		175 to 225	24
    		225 to 275	28
    		275 to 325	30
    		325 to 375	36
    		375 to 425	38
    Copper	165	25 to 75	14
    		75 to 125	16
    		125 to 175	18
    		175 to 225	22
    		225 to 275	24
    		275 to 325	26
    		325 to 375	30
    		375 to 425	32
    		425 to 475	36
    		475 to 525	40
    Table VI. E-W GAIN and W-E GAIN control settings at repeater
    Open-wire facility
    Type	Gauge (mils)	Length of preceding line section (miles)	E-W or W-E GAIN settings
    Copper-steel	080	25 to 35	26
    		35 to 45	30
    		45 to 55	32
    		55 to 65	36
    		65 to 75	38
    		75 to 85	42
    		85 to 95	46
    Copper-steel	104	45 to 65	28
    		65 to 85	32
    		85 to 105	36
    		105 to 125	40
    		125 to 145	44
    Copper-steel	128	60 to 90	28
    		90 to 120	32
    		120 to 150	36
    		150 to 180	40
    		180 to 210	44
    Copper	080	25 to 50	22
    		50 to 75	26
    		75 to 100	28
    		100 to 125	32
    		125 to 150	36
    		150 to 175	38
    		175 to 200	42
    		200 to 225	44
    Copper	104	50 to 90	24
    		90 to 130	26
    		130 to 170	30
    		170 to 210	34
    		210 to 250	38
    		250 to 290	40
    Open-wire facility			E-W or W-E GAIN settings
    Type	Gauge (mils)	Length of preceding line section (miles)
    Copper	128	75 to 125	24
    		125 to 175	28
    		175 to 225	30
    		225 to 275	34
    		275 to 325	38
    		325 to 375	42
    Copper	165	75 to 125	22
    		125 to 175	26
    		175 to 225	28
    		225 to 275	32
    		275 to 325	34
    		325 to 375	38
    		375 to 425	40
    		425 to 475	44
    37. Connecting Arrangements
    The terminals to which connections are to be made at an H carrier terminal installation are shown in figure 31, and those to be made at a repeater installation in figure 32. These over-all illustrations are supplemented by specific terminating and lineconnection illustrations in the paragraphs which follow.
    a.	Identification of Wires. The type H carrier equipment is wired internally so that each wire of a pair can be readily identified. One wire of a pair, designated tip (T), is a solid-colored wire while the other wire of the pair, designated ring (R), is identified by a tracer-color. The terminal strips are wired so that the tip (T) wire of each pair is connected to the right-hand (lower-numbered) terminal while the ring (R) wire of the pair is connected to the left-hand (higher-numbered) terminal. The paired connecting wire, supplied with the installing materials, is similarly color-coded. To facilitate maintenance and trouble location, whenever using the paired* connecting wire, connect the equipment so as to maintain the system of colorcoding.
    b.	Use of Shielded Wire. It is desirable that shielded wire be used for all connections where carrier frequencies are involved because of the greater coupling that occurs at the higher frequencies. Though a short length of color-coded shielded wire is supplied with type H carrier line panels, it may be necessary to obtain additional shielded wire locally. Whenever shielded wire is used, one end of the shield must be connected to the designated ground terminal. If the other end of the shield is not grounded, it must be taped for protection. Use the following procedure to ground the shield in the manner shown in figure 33.
    (1)	Remove about 2 inches of the cloth outer
    braid of the shielded wire from the end of the paired wire, exposing the braided tinned copper shield,
    (2)	Cut the exposed shield back about 1% inches from the end of the wire.
    (3)	Bunch together the frayed ends of the shield.
    (4)	Using about 6 inches of single-conductor cross-connecting wire, clean one end and wrap it around the bunched ends of the copper shield, making four or five close wraps.
    (5)	Solder the joint.
    (6)	Pull the cloth outside braid over the exposed copper shield and hold it in place by wrapping friction tape around the wire, making certain to cover the soldered connection.
    (7)	After cutting the single-conductor wire to the proper length, clean and solder it to the proper ground terminal on the terminal strip as indicated.
    33. Terminating Connections
    a.	The type H carrier channel may be terminated on either a two-wire or a four-wire basis. When terminated on a two-wire basis, the channel may be connected to an adjacent switchboard, a two-wire voice-frequency telegraph system, or a two-wire extension. When terminated on a four-wire basis, the channel may be connected to a four-wire voicefrequency telegraph system or it may be extended over a voice-frequency repeatered circuit, a channel of a type C carrier system, or another type H carrier system.
    b.	The terminating connections required are indicated by means of illustrations which show the terminating connections in diagrammatic and tabular form. The illustrations are so arranged that cither the diagram or the table may be used, as desired. Connection designations of specific terminals are given only for the type H carrier equipment. Connection designations of specific terminals on other equipment shown may be obtained by seeing the Technical Manual of the particular equipment. '
    Condition	See figure
    Two-wire termination	34 A.
    Four-wire termination	34 B.
    c.	The connections required to extend one H carrier system to another H carrier system when the two terminals are adjacently located are shown in figure 35. For operating advantages, the four-wire method of operation is used at the point at which the interconnection is made.
    39. External Balancing Network Connections
    Occasionally, when the type H carrier system is extended by means of extremely long voice-frequency
    42
    voice-frequency section of terminal voice-frequency section of terminal
    ARRANGED FOR 4-W OPERATION	ARRANGED FOR 2-W OPERATION	CARRIER-FREQUENCY SECTION OF TERMINAL_
    , । । । — -- -- -> |A9	R| HVB ___ I	MOD OUT GAIN INAMPLROUT
    Sm® i ZiZzfl&Fbc i l*!2—H--- N L-l_____|_bi I	J____|k-------□ n______	IE n
    ! * WHEN EQPT SW IS ON
    I 4W TLG THIS PAD IS
    I OUT OF CKT
    I i	I
    CwEST—/—TRANsl	I
    WIREj	\	/	FRADIO
    _____£	-_______£ £-------	(east-x\ /^REcJ
    I I	H CARRIER
    I	HYB	, I	\\	line panel
    rlzLJ BAL NET । I	\>	i----—[i
    5 I	TO -----O o—Ht-Tmr-t—TW—iH-o-o-. I ]	L-l	LINE SWITCH	" ---» <-
    si	'' °sc	'«« !o°cx°t
    "I	4W	!ZZZ HHYB 6OOC.I I !	7,50	FIL LINEgj LL ____J
    I -vV." ii	L~। T____________________	JlTi
    < I	II	। । । ।	| I	-------- 1 TO , A8I
    Xt	I	’ voiceI LOW o
    R? 7.6-	CKT | PASS -L
    °|	EQPT SWITCH	|	।	pad	II	EQUlP Ia6 SEC’J |
    RFC I I 4W . ,-I REC I I REC REC	DEM REC	| |Bl J
    OUT dl I teWl r OUT Jl£MPLRIN______________________ DEM IN ____ GAIN	| yo | <— DEM	I BALNETl	f BAL NET. FZKZ---------v /tlg	TFI Z 111regzrorbf	15lv-°Fi LFN CKJ-°F
    irech-qut	i \\ i . L \ n MjlxJ____________________________________ I %trk tntr
    1^2 H---------1 I----£1	z> ..... -J I H zp L—1	I-1	I ' _1	I hcarr P-HCARR
    I.	I	EQPT SWITCH	| I	I PAIR iB7,--85, PAIR
    I	I I	II	I TO LINE
    I____________________J I_________________________-JI---------------------------------------IFR TO LINE
    C	R	| LFB | %UJR
    NOTES:	EQNON?H ,BS	06
    I.	FOR 2-WIRE OPERATION, USE A AND B	CARR 1^-- I <7,AR5
    2.	FOR 4-WIRE OPERATION, USE A AND C	. pA|R |B9	Bill PAIR
    3.	LETTERS cl, b, c, d AND e ARE SHOWN ONLY	A	o-l -o
    FOR IDENTIFICATION.	s	TO |	| TO
    4.	TO OPERATE AS A WEST TERMINAL TURN	BAL NET lip	I BAL NET
    LINE SWITCH TO WIRE-WEST POSITION	SIDE OF	CKT OF
    THIS INTERCHANGES BAND FILTERS BF	V-F I BN I V-F
    REPTR |o,n	o|p| REPTR
    ON |B4°-	-®L2 ON
    NON-H I J- NON-H
    CARR IBO.- BIS I CARR
    I	PA IR i °° I PA IR
    mote:	‘S symbol for fixed capacitor.	1 DLJ
    1	TO I P H I TO
    BAL NET I LF BAL NE1 SIDE OF dm I CKT OF PH ria ria PH V-F REPTR HQ _%6I REPTR L-’ZZZ—1
    TL5I3O5
    Figure 31. Terminal connections, zvire operation.
    43
    H CARRIER REPEATER PANEL W-E W-E W-E	W-E	I
    ml	AMPLR	OUT	|
    | f	।	H CARRIER
    S	7 S	I	line	panel
    I*/ —dab'	1,	। I, M-------------------------------1	I	r_c—;
    '7	—F—h—Il	n—h—+—p	7'
    orPcxOT| "St I I line—™ WDF	EOFo«—Jne! I ?St
    sect,o. I	nLT ~linc	I	I sP«ss0N I 0RCX
    |A2	A4I	l 2 tq	F—]	, I	I..	,_l
    CUI °	6 6 I. ,1 E-W E-W E-W E-W I I---------------------------------O”m--------—r°
    I LF I	I I	OUT AMPLR IN y GAIN |	|	j I	1 LF
    I i si	—^rfdhPt	w r J i
    PASS I TO VOICE I	----------L—	--J L----X_------- j vO|Cr ' L0W‘
    I	r/AdO	mt HP 1	------ TO VOIC,E- I PASS
    SECTION I	CK.T EQUIP	(	(	CKT EQUIP '	ScCT10N
    '	L _*6I	1	I IA6
    i	i—n	l-------------------------------------------------------------------->	 p	i
    I	I	I	1
    B3 -------1 Bl I	I _______	'
    C^T OF vV I O	। ST)F OLF	TOBALNEtX	---O TO BAL NET
    REPTR ON	LFN I REPTR ON	SIDE OF V-F |	CKT OF V-F
    HCARRPAIR|B4_	_^| H CARR PAIR	H CARPER | B2 U	S4|7c7RRp™R
    I	'	I
    ] B5 ------1B7 I	' ________ ।
    TO LINE j”	~°|oFCOL^NE	TO LINE SIDE | CH	-^o|tQLINE
    EQUIPON	LFB	VOICE EQUIF	OF COIL in	EQUIPON
    NON-H B6	B8loNNON-H	VOICE EQUIP LFB	lN0N-H
    CARR PAIR Io-	-o I UN" ON H	ON NON-H |B8	__| CARR PAIR
    |	______ CAKK HAIR	CARR PAIR I	,
    lB|i ______, ।	|	|
    TckBtAofNvf j LF BN^Fs^^v-k	weofNv< 1 ^ji-F bnH^1 |Tc°7olfNv7
    NON-H | BI2	BIO NON-H	REPTR ON |	------ I REPTR ON
    CARR PAIR O----------O '+doag	NON-H BlO	Bl2| NON-H
    CARR PAIR I	( CARR PAIR	CARR PA,R O---------O , CARR PAIR
    1	I	'
    ! CH- PH Uo3l	I B'3f KZj BI5|
    cX^T, <-F BN i;?7AoLFNp+	w BAL NET |%f bn O|TO BAL NET.
    V-F REPTR I BI6_l-- B,4 V-F REPTR	, J------	|	R^S
    I o---------O I
    L----------J	[_	1
    1-------------' TL5I30B
    Figure 32. Repeater connections.
    44
    ------OUTER BRAID -----paper
    / .--BRAIDED TINNED
    / / COPPER SHIELDING
    /	.— RUBBER COVERING
    / / f- CONDUCTOR COVERING
    / / / CONDUCTORS--->.
    approx i >/z—
    22 GA SB WIRE----'	\	SHIELD WIRES FRAYED
    SINGLE OR LOOP	\	AND TWISTED TOGETHER
    LEAD AS REQUIRED	\ SOLDered PIGTAIL
    CONNECTION
    TL5I565
    Figure 33. Method of grounding the shield of shielded wire.
    E 2 Ma w>rs~2
    0 *
    u r/WMv 1
    P <	> ? H CARR TERM. . ..
    E	G	/
    IR	—is	\
    ( 16—16 J	\
    H CARRTERM. TERM.STRIP (-----------------,____________________I
    i )	TRc=>^ MOD ________)
    IN f
    /	AIO	)
    A7	I /	/
    D	P—^2W	\	\
    TO 2-WIRE	R	<	)	)
    V-F EQUIP.	O ■=>—<= HYB /	T04-WIRE	/
    p TAT	V‘F EQUIP-	/
    \ /
    A 8	l—l-----	/	1
    \	_ All	/
    IM
    1	REC XL DEM  --------- (
    J	0UT
    »	A12	I
    A	\
    B
    TL 51274
    A. Connections for two-wire termination.
    	Connect	from		To
    Step	Terminal	Strip	Location		Use
    1	7 and 8	A B. Connections for four-wire termination. Connect from			Terminal panel.	Two-wire- v-f tp equip, or two-wire v-f tg term. To	Paired wire.
    Step	Terminal	Strip	Location		Use
    1	9 and 10	A	Terminal panel.	Send side of four-wire v-f tp or tg equip.	Paired wire.
    2	11 and 12	A	Terminal panel.	Receive side of four-	Paired wire.
    wire v-f tp or tg equip.
    Figure 34. Terminating connections.
    45
    H CARRIER TERMINAL PANEL	H CARRIER TERMINAL PANEL
    ? tr	a. ?
    o *"	H o	v
    J -------------I—I--1_|------oXS-l______________________________l_|__  \
    \ 4W	cHoYiBl	4W I
    r?wTELT^_______“____“-____-------------v\ //------C>G7i. _	_ t4el 4W
    2W ! TLG	\ \ / /	---- ----------- 2W • TLG
    LI	8 y AA y 1	U v
    \ EQpT	2	/ A \ a 2	FOPT \
    \ SWITCH	Ul §	/ /\ \ aii 5 W	SWITCH \
    J	------- O T All / / \ \ All Q	________ PWIICH \
    dem	—*-_____ A|2	/	\	A|2__----- DEM
    ---------.'J-Q— —J V—-Q-GTJ______________________
    CONNECT TERMINALS A9 AND AIO OF EACH PANEL TO TERMINALS	TlSOSIO-S
    All AND AI2 OF THE OTHER PANEL.
    Figure 35,
    Connection of two type H
    carrier terminals on a four-wire basis.
    facilities, it may be desirable to use an external balancing network. To connect an external balancing network, remove the strap between terminals Cl and C2 and the strap between terminals C3 and C4 of terminal strip C on the terminal panel (fig. 28) and connect a suitable external balancing network to terminals Cl and C3.
    40. Line Connections
    a. Wire Operation. Though the type H carrier equipment can be connected for wire operation in many ways, this paragraph is concerned only with the line connections required for the more common arrangements in a physical circuit. The line connections required for operation on a voice-frequency repeatered physical circuit, a composited physical circuit, and a simplexed physical circuit are shown by means of figures. Connection designations of specific terminals are given only for the type H carrier equipment. Connection designations of specific terminals on other equipment shown may be obtained by seeing the Technical Manual of the particular equipment or to TM 11-2037. The more common arrangements on a physical circuit are listed below together with corresponding references to figures showing the line connections required.
    Condition
    Physical circuit w i t h voice-frequency telephone repeater and composite telegraph.
    Physical circuit with composite telegraph.
    Physical circuit with simplex telegraph.
    East terminal or West side of repeater Figure 36
    West terminal or East side of repeater Figure 37
    Figure 38
    Figure 40
    Figure 39
    Figure 41
    b. Radio Link Operation. Various line connections and interpanel connections are required for radio link operation. The line and interpanel connections required for radio link operation are indicated by means of an illustration which shows the terminating connections in diagrammatic and tabular form. The illustration is so arranged that either the diagram or the table may be used, as desired (fig. 42). Connection designations of specific terminals are given only for the type H terminal equipment. Connection designations of specific terminals of the radio equipment may be obtained by seeing the Technical Manual of the particular radio equipment used.
    41. Carrier Transfer Equipment Connections
    If it is necessary to terminate the voice or d-c telegraph circuit, or to transfer the carrier circuit at an intermediate point where a carrier repeater is not provided, two carrier line panels and associated terminating equipment are required. The connections required for the carrier transfer equipment only are. given below. No vacuum tubes or power supply is required.
    a. Ground Connections. (1) Clean one end of a 6-foot length of single-conductor copper wire and solder it to terminal 8 of terminal strip A on the upper line panel (fig. 29).
    (2)	Run the wire along the side of the cabinet to the lower line panel and loop the wire so as to make connection to terminal 8 of terminal strip A on the lower line panel.
    (3)	Solder the loop connection made in (2) above.
    (4)	Run the wire to the cabinet ground connection and solder.
    (5)	Tie the ground wire to the cabinet supports.
    b. Equipment Connections.
    Condition
    Physical circuit with voice-frequency telephone repeater and composite telegraph.
    Physical circuit with composite telegraph.
    Physical circuit with simplex telegraph.
    West side East side
    Figure 43	Figure 44
    Figure 45	Figure 46
    Figure 47	Figure 48
    42. Check of System Performance
    A check of system performance is made after completion of the equipment connections and adjustments to insure satisfactory system performance. This is done by talking between terminals on a two-wire basis and by ringing over the circuit if the channel is terminated at an adjacent switchboard or in a telephone set.
    a.	Talking. Set switches EQPT at both terminals on position 2W to permit talking on a two-wire basis. A magneto telephone may be patched into jacks 2W HYB at each terminal to talk. If the type H carrier terminal is located near a type C carrier terminal, the telephone set of the C carrier terminal may be used. Upon completion of conversation, restore switch EQ PT at each terminal to the original position. Before undertaking extensive tests or repairs, perform the detailed tests, adjustments, and line-up procedure contained in section V. If, after these tests and adjustments have been performed, irregularities in performance persist, see section XV.
    b.	Signaling. If the channel is terminated at an adjacent switchboard or in a telephone set, ring over the circuit to check the signaling. In the event of failure, see section XV.
    46
    47
    d f e :r
    e s
    5, ?,
    e
    n
    r f
    PARENTHESES INDICATE DESIGNATIONS OF CARRIER REPEATER
    E »	1 r f
    °	»	o	•>
    u 3—	rj^r-3	.	r.	p
    o y ‘	f4	\ vof—4	I	r	।	r	*
    P < 5- 4ZL5 f 1 P <	OmZ >7	H cflRR TERM- (0R REP)
    E	6 g c	n	\
    NX AAXSl X	u e	Yf A0!	r
    7—4-r®V\v*7	m	iwiW	G	—•“	/
    1	„ yfz—\Aj _	N	tz A°\ 44	._____/
    7	T. I5-ZZ^ W>~- 15	n Aid)	_l_	\
    TERM. STRIP IN REPTR AND TERM	\	7	k- 1------ /
    STRIP A IN LINE PANEL	Tr»u ctoio □ in i imp panfi anr	t H OIR FILT OF	/
    TERM STRIPBIN LINE PANEL AND	LINE	»> < LINE ( W DFi
    TERM.STRIPA IN TERM	FILT	„	1=1-C=1 (W OlR '
    H CARR LINE PANEL	(WLINEFILT)	□ CZI FILT LINE) &|R
    A 2 (2)*	f* J	FIL
    prot ex	r—-----------—O------------J 1-------L _ J /
    r -]	।	,	L F AT----	--4:----------------------
    SECTION	”1
    TO D-c ■=■ ------
    TG EQUIP
    . B3|-----r - - - --RAP2R________________________________
    B4 LFN B2	|	i--------\
    ri__________r-q  r-G=H
    _______________I	line	I	}	I
    i	°	I	HYB	I	\
    -----------------1-o_______I	l	\
    ------------- !	NET. 1	।	\
    ------------------ 1 o......I	।	\
    i
    I	1 LINE^AND I	\
    I	! “-------; I	\
    “ I 0------l_BAL NET.,	\
    Connect from	’Po
    Step	Terminal	Strip	Location	Terminal	Strip	Location	Use
    1	WEST			Through prots to CX (line			Shielded wire.
    	line pair			side ).
    2	1 and 2	A	Line panel.	CX (drop side).			Shielded wire
    3	3 and 4	A	Line panel.	1 and 2	A	Terminal panel.	Shielded wire.
    				or 1 and 2		Repeater panel.
    4	5 and 6	A	Line panel.	V-f tp reptr (hyb line).			Paired wire.
    5	7	A	Line panel.	Shield of wire in step 3.			Insulated wire.
    6	8	A	Line panel.	Shield of wire in step 2.			Insulated wire.
    7	1 and 2	B	Line panel.	V-f tp reptr (hyb net).			Paired wire.
    8	3 and 4	B	Line panel.	V-f tp reptr (line and ex			Paired wire.
    				bal net).
    9	3	A	Terminal panel.	Shield of wire in step 3.			Insulated wire.
    or	3		Repeater panel.
    Figure 36. Connections for East terminal or West side of repeater, with voice-frequency telephone repeater and composite telegraph.
    FL 51276
    48
    G>Z
    o I w £ f 2	1
    U 3~	1 U	T
    H CARR TERM. (OR REP)*	p<	H 1 )	7 R
    Ezzzzz-------------------- m 1 5~z?nr5 n px	> »
    --r—	E	6-+\^k-6	G	P	MW _ZL	N	7+W+*7	E.	OW
    *	7	a -L7=AA-r	n
    II _____ _____________(5)4_O	T	615-^—15
    I	L-----1	0	——————. T£RM. STRIP IN REPTR AND	’®/	16
    DF * DIR FILT ++ LINE	TERM ST RIP A IN LINE PANEL term. STRIPS IN LINE PANEL AND TERM.
    I (E DF) LINE (=3-C3 FILT	#	STRIPA INTERM.
    (E DIR .—,	, (ELINEFILT)
    I 01R	Fl LT LINE)	„	H CARR LINE PANEL
    fil	r—d_	A2
    __ ——---- 0 cx p
    (7)A3 Y	।-—J—] L F	I I l 1 \
    JT---	L4pi^r^TF_Lr+L_n_+ cJ-4 4- east
    ----- ~	A4 PASS A2 !_ I I	LINE
    1—------------------------ —yr tJ
    y~ □ r4 4--i	L-j
    SECTION	|	I |
    -----	—	TO D-C
    VF TP REPTR	_	----- TG C0UIP
    —-------- - —-   —. —   	O I	D 5
    / K	I	r~--c-	------
    ~~^j	I	[—£- LFN —!52—
    \	i	i	l,ne
    !	HYB	I----o-J----------
    /	I	I	NET.	।	---------
    2——7
    I	N! r------ I
    /	| LINE AND ___-	____________________________
    i	1 cx	~~ I
    J	l_b2L .N£L.jr	°—J	"	——	■
    *PARENTHESES INDICATE DESIGNATIONS OF CARRIER REPEATER
    Connect from	To
    Step	Terminal	Strip	Location	Terminal	Strip	Location	Use
    1	EAST			Through prots to CX (line			Shielded wire.
    	line pair			side).
    2	1 and 2	A	Line panel.	CX (drop side).			Shielded wire.
    3	3 and 4	A	Line panel.	1 and 2	A	Terminal panel.	Shielded wire.
    				or 5 and 6		Repeater panel.
    4	5 and 6	A	Line panel.	V-f tp reptr (hyb line).			Paired wire.
    5	7	A	Line panel.	Shield of wire in step 3.			Insulated wire.
    6	8	A	Line panel.	Shield of wire in step 2.			Insulated wire.
    7	1 and 2	B	Line panel.	V-f tp reptr (hyb net).			Paired wire.
    8	3 and 4	B	Line panel.	V-f tp reptr (line and cx			Paired wire.
    				bal net).
    9	3	A	Terminal panel.	Shield of wire in step 3.			Insulated wire.
    or	7		Repeater panel.
    Figure	37. Connections for		West terminal or	Fast side of repeater, with voice-frequency telephone repeater and com-
    posite telegraph.
    49
    H CARR TERMINAL (OR REP)*
    I	|
    W ______________AI(Q* ________________________I l
    I-----------------------------I. I-----■------ D F	\
    7 I	R	LINE	I H	DI”'	(WDF)*	)
    <	।	filt	XX	f-ilt	tw0F)	/
    N «■	(WLINE	LINE	(
    <5	FILT)*	O-C=l	(W OIR	\
    A2(2)* LU	D,R '	)
    15	-------U------LNe, Flt	/
    \	■- J	|	A3(3)*	~T~L_____________4
    TERMINAL STRIP IN REPTR TERMINAL STRIP A	X	L. * —J
    AND TERMINAL STRIP A	IN TERMINAL	L—_______________________________________I
    IN LINE PANEL H CARR LINE PANEL A7
    PROT ox	L F
    r—q	r—|	i JL
    z !	1 n ai _ high- 0
    C---1-0 0-4-1-0 o4-------o-----O-	---------------------
    WEST	I	PASS
    U«	4II	SECT,0N -Uil-U-----------------
    L.J	L;.;J f	-7— A5 -
    L LOW	o--	——	RpTG
    I I	PASS a6	COIL
    TO D-C AS ---------- ----------------------------n	r------~n
    TG EQUIP1---? SECTI0N	I |
    _L ------------ I 1	.
    --- ,_____   | -o O-t"-"— TO V-F
    ---------------------J	|	|--------EQUIP. -----------------------------------------------------------------------------------------L< -J
    * PARENTHESES INDICATE DESIGNATIONS OF CARRIER REPEATER	I___*'__|
    ---------- TO GND
    TL5I278
    Connect from				To
    Step	Terminal	Strip	Location	Terminal		Strip	Location	Use
    1	WEST			Through prots to CX	(line		Shielded wire.
    	line pair			side).
    2	1 and 2	A	Line panel.	CX (drop side).			Shielded wire.
    3	3 and 4	A	Line panel.	1 and 2		A Terminal panel.	Shielded wire.
    				or 1 and 2		..	Repeater panel.
    4	5 and 6	A	Line panel.	Rptg coil (line side).			Paired wire.
    5	7	A	Line panel.	Shield of wire in step	3.		Insulated wire.
    6	8	A	Line panel.	Shield of wire in step	2.		Insulated wire.
    7	3	A	Terminal panel.	Shield of wire in step	3.		Insulated wire.
    or	3		Repeater panel.
    Figure 38. Connections for East terminal or IFest side of repeater, with composite telegraph.
    50
    Connect from	To
    Step 1 2	Terminal EAST line pa 1 and 2	Strip iir A	Location Line panel.	Terminal Through prots to CX (line side). CX (drop side).	Strip	Location	Use Shielded wire. Shielded wire.
    3	3 and 4	A	Line panel.	1 and 2	A	Terminal panel.	Shielded wire.
    				or 5 and 6		Repeater panel.
    4	5 and 6	A	Line panel.	Rptg coil (line side).			Paired wire.
    5	7	'A	Line panel.	Shield of wire in step 3.			Insulated wire.
    6	8	A	Line panel.	Shield of wire in step 2.			Insulated wire.
    7	3	A	Terminal panel.	Shield of wire in step 3.			Insulated wire.
    or	7		Repeater panel.
    Figure 39. Connections for West terminal or East side of repeater, with composite telegraph.
    e	] e
    q &c\ vCT uu t	\ 2
    H CARR TERM (OR REP)*	U	3—•M^-3	7 Q	w
    /	* J 4—4/Vjf-4 1 r	y	wlw	9
    *	E 6~* &\\ \Fr 6 G	r	(Ct"\	N
    ~1	t	7~uzvvr7 n	G
    "|	(5) Al,* _________ I 8_J^=^_8 I N
    --------O—---a---------	v	'	1	15 VtWA otwv—I 5
    LINE	16 -r+t5/	kJ^|6
    FILT	C	'
    (E DIR	'	'	J—5	(E LINE	TERM STRIP IN REPTR AND
    F,L'r	Er1	U3	FILT)	TERM STRIP A IN LINE PANEL	TERM STRIP A IN TERM
    DIR LINE)*AS (6)A2*
    FIL ---------1	"--------O----H-----
    ]J	»7) A3* ___ H CARR LINE PANEL
    /---—------- -=•	c	CX	PROT
    L....	.......................... r——O 1 L_F 	r----r---T
    1 A3 I	Al J I !	' _
    '--4— —O—F—L- high-	p|-|-O	O-+—-4-O	O |	FAST
    A*	PASS	A2 ।	'	' I LINE
    O SECTION --f—O------t-"T-0	CM™—J~O	O ■
    A 5	_____	?	? ’	'	'
    tUBiifa xa ■ m mi i-rarga	1	L L « 1 J C %~ - SECTION-o-L4—--—J	(
    I y «e ------------ kJ a5 U
    I	L=-~=O L LOW- -------O——--——
    V	PASS A6
    SECTION --------“™|
    * PARENTHESES INDICATE DESIGNATIONS OF CARRIER REPEATER
    RPTG COIL
    TO V-F
    EQUIP
    TOO-C TG EQUIP
    OR GND
    tl sueo
    Connect from	To
    Step	Terminal	Strip	Location	Terminal	Strip	Location	Use
    1	WEST			Prots (line side).			Shielded wire.
    	line pair
    2	1 and 2	A	Line panel.	Trots (drop side).			Shielded wire.
    3	3 and 4	A	Line panel.	1 and 2	A	Terminal panel.	Shielded wire.
    				or 1 and 2		Repeater panel.
    4	5 and 6	A	Line panel.	Rptg coil (line side).			Paired wire.
    5	7	A	Line panel.	Shield of wire in step 3.			Insulated wire.
    6	8	A	Line panel.	Shield of wire in step 2.			Insulated wire.
    7	3	A	Terminal panel.	Shield of wire in step 3.			Insulated wire.
    or	3		Repeater panel.
    Figure 40. Connections for East terminal or West side of repeater, with simplex telegraph.
    52
    Connect from	To
    Step	Terminal	Strip	Location	Terminal	Strip	Location	Use
    1	EAST			Prots (line side).			Shielded wire.
    	line pair
    2	1 and 2	A	Line panel.	Prots (drop side).			Shielded wire.
    3	3 and 4	A	Line panel.	1 and 2	A	Terminal panel.	Shielded wire.
    				or 5 and 6	• •	Repeater panel.
    4	5 and 6	A	Line panel.	Rptg coil (line side).			Paired wire.
    5	7	A	Line panel.	Shield of wire in step 3.			Insulated wire.
    6	8	A	Line panel.	Shield of wire in step 2.			Insulated wire.
    7	3	A	Terminal panel.	Shield of wire in step 3.			Insulated wire.
    or	7		Repeater panel.
    Figure 11. Connections for West terminal or East side of repeater, with simplex telegraph.
    r,—VLtL
    q 2~§\W“2 w R	*
    H CARR TERM. (OR REP)*	U 3~ TCtV®’'3 I I	1
    f----------------- ------------------ • J 4—•<^f~4 I R	p J	I R
    	m । 5^>nr5 n	y	i n
    T -------------,	.------"liL---Q________ T	1 . ,6is^^_,5
    <£ OF I* oiR FILT 1 J	-
    LINE r-J ,—, LINE FILT	„	TERM STRIP IN REPTR AND TERM STRIP A IN TERM.
    ,	ici inc curt*	TERM. STRIP A IN LINE PANEL
    (E OIR FILT a-1-1  ?
    4 Ir	8~TOv&8 ( L
    st'	r	ft/W im	n
    5 n	,	\W>	g
    6 G	T	WW
    8 J	^16 —^^6 5^
    TERM STRIP A IN LINE PANEL	TERM STRIP A ANOB IN TERM.
    H CARR TERM._____________ HCARR LINE PANEL
    A3	A7 [TP
    /	J-----°—1	I—Al----------	>
    _A7	~	Al p|	P| A3p| men- Al
    TO 2-WIRE ~	TERM. #■ 1 (TRANSMIT)	°“	~‘°"	°” TO RADIO
    CH1	PASS
    V-F EQUIP	AB	A2	A4	AZ XMTR
    — —-O	O— j— --------j SECTION	—
    A16	A8
    Or-	1	■■  .. —O
    81 B2 83	84 85 86 87	88	89 810 811 812	<	(~
    <	\	Aj low- —I
    SEND	PASS
    A6
    SECTION
    — ______________I
    TO 4-WIRE V'F
    TP °R TG E0UIPJ	HCARR LINE PANEL
    L F
    LOW-
    RECEIVE	PASS
    '	'	J	-------- SECTION _
    ooodoooodoiA / B1 82	83	84	85	86 B7 88 89	810 811 812 Z	<_
    /	M
    /	Al6	~ZY._ --- .
    TERM # 2 (RECEIVE)	P	P ~P	A1 i
    — —c	o—---------------—O- — - HIGH- ko——
    ° 2'WIRE CH2 A7	A’	A3	PASS	T0 RflD,°
    V’F EOUIP____	__________________A4__ SECT|0N	RCVP
    k “	^1_______iZ?YZ2L—K '
    ______________________________A3 HCARR TERM.________Tl 9I2O J
    Connect from	To
    54
    Bf 1Rx
    2 w	y I	1
    p^4xxw~4 U	u	H
    mi s-'TPvVks I 1	E	r
    E 6-*X%.6 N	H CARR LINE PANEL	N	Q/Ya iWV	G
    ? dM^7 r, .... tt) T
    »	7	'J18	AZz	J
    TERM STRIP	p.	x	TERM. STRIP
    A	T , LF , S	8
    PROT	c X
    to r—cuTd___crz^ A-4™_	-n-<~ a —'i	t°
    WEST ||	|| I	high- n y	TERMINALS
    LINE |	I	I	AZ	PASS	A3 AND A4 OF
    X ' "| o 0—|	—9 g |	<_J -°T— SECTION —kJ—**■ kJ —J EAST LINE
    1---J	|—X	panel
    TO D-C TG EQUIP	a5
    “ LOW—	————
    PASS	AB
    ----SECT)0N	»■ ..... ll-
    ----—J	v.p Tp REpTW
    7
    9 3	-------0'	I . J
     *-f N | ~ rJjZ^7
    | LINE	|
    _______Lq_ nr a |
    Inet I
    ______________________________:
    I———————————— [—0—) LINE ad
    I GX | p l£AL NELl
    TL 5'2»»
    	Connect from				To
    Step	Terminal	Strip	Location	Terminal	Strip	Location	Use
    1	WEST			Through prots to CX (line		Shielded wire.
    	line pair			side).
    2	1 and 2	A	Line panel.	CX (drop side).		Shielded wire.
    3	3 and 4	A	Line panel	3 and 4	A	Line panel	Shielded wire.
    			(WEST).		(EAST).
    4	5 and 6	A	Line panel.	V-f tp reptr (hyb line).		Paired wire.
    5	7	A	Line panel.	Shield of wire in step 3.	•	Insulated wire.
    6	7	A	Line panel.	4	A	Line panel.	Strap wire.
    /	/	A	Line panel.	8	A	Line panel.	Strap wire.
    o	8	A	Line panel.	Shield of wire in step 2.		Insulated wire.
    9	1 and 2	B	Line panel.	V-f tp reptr (hyb net).		Paired wire.
    10	3 and 4	B	Line panel.	V-f tp reptr (line and ex		Paired wire.
    bal net).
    Figure 43. Connections for West side at transfer point, with voice-frequency telephone repeater and composite telegraph.
    55
    ________________Connect from	To
    Step	Terminal	Strip	Location	Terminal	Strip	Location	Use
    1	EAST			Through prots to CX (line			Shielded wire.
    	line pair			side).
    2	1 and 2	A	Line panel.	CX (drop side).			Shielded wire.
    3	3 and 4	A	Line panel	3 and 4	A	Line panel	Shielded wire.
    			(EAST).			(WEST).
    4	5 and 6	A	Line panel.	V-f tp reptr (hyb line).			Paired wire.
    5	7	A	Line panel.	Shield of wire in step 3.			Insulated wire.
    6	7	A	Line panel.	4	A	Line panel.	Strap wire.
    7	7	A	Line panel.	8	A	Line panel.	Strap wire.
    8	8	A	Line panel.	Shield of wire in step 2.			Insulated wire.
    9	1 and 2	B	Line panel.	V-f tp reptr (hyb net).			Paired wire.
    10	3 and 4	B	Line panel.	V-f tp reptr (line and ex			Paired wire.
    				bal net).
    Figure 44. C onnections for East side at transfer point, with -voice-frequency telephone repeater and composite telegraph.
    s'	o	o W2
    r~2	u	’A Mx	*
    H	h	m ]	f n
    M	5	Wf5	|i	E	raw	r
    E	6—Ao>L— c	2?	kj - (azA A Avjx	6
    N 7— A\rSC; G	H CARR LINE PANEL	r
    ’ J r ...	—i	(J
    TERM STRIP	----W	-- TERM STRIP
    A	/	L	8
    ' L F
    To	CX	PROT
    terminals/___A a3 A	____ai A r_~7~i r~r~i x to
    A 3 AN D A 4	T	HIGH- - O-	I—° O-j	0—| > EAST
    OF WEST	X A4	PASS	fl2	III LINE
    LINE PANEL >■'	o '3—O— SECTION — —--O--—| -O O-'|—"" |-O O |
    '	TO D-C
    A5	tg eouir
    L 0 W -A6	PASS
    SECTION
    WF TP REPTR	--------
    I----------1
    /	I	81	-------- B 3
    --■!/	|	B2	LFN	B4
    ^J_L	---<3 —	--—4>—.
    P IpJJ	L—J
    I	| LINE |
    H>A-----	--------------"---
    I	EtU
    LSt ;
    pj—I
    ["line b””A0-' | -———————_-------------- ■
    [A.net]—c>-|—-------------------------------
    56
    e ('“ISr 1
    i J 4— + W-4 IR m ) 5- imr5 i n
    H CARR LINE PANEL	£	6"» ®C\ W-6 ft
    I---------------------1 t 7^iOr7
    ------------------ I e—b
    \ AB	AT -z	'
    -.___________________oZ_ 	TERM. STRIP
    ■i	\	A
    PROT	CX	. ,	]
    I---1	।---1	---—---
    I 1	1	1 A!	Jas I
    west r------r M—1~* H—n——f+—A-------------------------------1To terminals
    UNE ________!	I	I I____I A2 S£CTl0N	Aa+	AS ANO A4 OP
    I-------1° H----1~°	|-----°~!--w-ction --y^---y---------J EAST line panel
    I---1	L|_|J
    WO-C	LOW-PASS ------
    TO EQUIP	 9£CTl0N ______£
    RPTG
    COIL
    F’“l
    I *1 ]TOV-F
    L------)_<, o_|- iou'p
    L1J
    I—.... TO ONO
    n-tiau
    	Connect from				To
    Step	Terminal	Strip	Location	Terminal	Strip	Location	Use
    1	WEST			Through prots to CX (line			Shielded wire.
    	line pair			side).
    2	1 and 2	A	Line panel.	CX (drop side).			Shielded wire.
    3	3 and 4	A	Line panel	3 and 4	A	Line panel	Shielded wire.
    			(WEST).			(EAST).
    4	5 and 6	A	Line panel.	Rptg coil (line side).			Paired wire.
    5	7	A	Line panel.	Shield of wire in step 3.			Insulated wire.
    6	7	A	Line panel.	4	A	Line panel.	Strap wire.
    7	7	A	Line panel.	8	A	Line panel.	Strap wire.
    8	8	A	Line panel.	Shield of wire in step 2.			Insulated wire.
    Figure 45. Connections for West side at transfer point, with composite telegraph.
    57
    TEXAS STATE COLLEGE FOR WOMEN
    library
    E f 1
    Q ? SA WLt w I J 4-" t&A ■ A I R M | 5— 5^ vffP | N H CARR LINE PANEL	£	6~*	G
    ---------------------------  N	7 H 71+7 I ____________________________________A T I
    '.A7	A8y
    .___S>_—	HL---	TERM STRIP
    LF
    C X	PROT
    JL A3 X	Al 1 I- “1 r ■	.
    /	( y ___-o .,}_ ______________o— ■■■■(	o o l -T—o of**
    TO TERMINALS	T	HIGH-PASS	I	. EAST
    A3ANDA40F	X fl4	SECTION	fl2	I .	LINE
    west line	i—y—^y-	—r<—y-------------y? °	—
    PANEL	■—F—T—J 1------1
    TO D-C A5	TG EQUIP.
    lOW-PASS
    A6	SECTION
    RPTG COIL I---1
    f___l—o o-i____
    TO V-F dQUIP I I ---------f-O O—|	 1 9	1
    L_L_J
    TO GNO ------'
    	Connect from				To
    Step	Terminal	Strip	Location	Terminal	Strip	Location	Use
    1	EAST			Through prots to CX (line		Shielded wire.
    	line pair			side).
    2	1 and 2	A '	Line panel.	CX (drop side).		Shielded wire.
    3	3 and 4	A	Line panel	3 and 4	A	Line panel	Shielded wire.
    			(EAST).		(WEST).
    4	5 and 6	A	Line panel.	Rptg coil (line side).		Paired wire.
    5	7	A	Line panel.	Shield of wire in step 3.		Insulated wire.
    6	7	A	Line panel.	4	A	Line panel.	Strap wire.
    7	7	A	Line panel.	8	A	Line panel.	Strap wire.
    8	8	A	Line panel.	Shield of wire in step 2.		Insulated wire.
    Figure 46. Connections for East side at transfer point, with composite telegraph.
    58
    Connect from	To
    Step	Terminal	Strip	Location	Terminal	Strip	Location	Use
    1	WEST			Prots (line side).			Shielded wire.
    	line pair
    2	1 and 2	A	Line panel.	Prots (drop side).			Shielded wire.
    3	3 and 4	A	Line panel	3 and 4	A	Line panel	Shielded wire.
    			(WEST).			(EAST).
    4	5 and 6	A	Line panel.	Rptg coil (line side).			Paired wire.
    5	7	A	Line panel.	Shield of wire in step 3.			Insulated wire.
    6	7	A	Line panel.	4	A	Line panel.	Strap wire.
    7	7	A	Line panel.	8	A	Line panel.	Strap wire.
    8	8	A	Line panel.	Shield of wire in step 2.			Insulated wire.
    Figure 47. Connections for West side at transfer point, with simplex telegraph.
    2	w
    3	।
    4	I R
    5	li
    6	G
    7 Q
    < '	J	H CARR LINE PANEL
    term strip r	*~~n
    A r—v8	Akf
    L F	\
    PROT
    x ! I AAI	A A3 A k
    west J“° i	"° T~ HIGH<.' | ~|	1 TO TERMINALS
    L'NE ' , J____________ AZ. • s7cST|Son A4,<	AS AND A4 OF
    k I--0	y----"°"T----	<>----y-------) EAST LINE PANEL
    A5 — low- ------------------—
    PASS •	 SECTION	Aq___
    •
    R PTG COIL
    I------1 N
    L" "I °” |	TO V-F
    I	EQUIP
    I o o r
    • o 1
    L__l—J
    I TO D-C TG EQUIP OR GND
    TL 51287
    59
    E ( 2-
    8	4+	«
    I	J	4—.	ZZUj—4	I	r
    M	|	5~	T^VW*5	|	?.
    H CARR LINE PANEL	E	6 r
    r--------------------1	?	G
    -y)	(e JMJL, J
    Z3	)(dl±+ *-------------- CARRIER -----------v k++^ v ATTENUATOR v	° MEASURING
    (A 7 TERMINAL 7 (A	‘ O . SET -
    'C DB
    PATCH OSCILLATOR OSCILLATOR
    SWITCH EQPT OSCILLATOR OUTPUT LEVEL FREQUENCY	REQUIREMENT:
    0H_______TO JACKS________________________ TRANSMITTING OUTPUT SHOULD BE
    2W	2W HYB 0 DBM	1,000 CYCLES	WITHIN tl.5 DB OF SPECIFIED OUTPUT
    NW TEL ~ MOD IN	+N DBM	1,000 CYCLES
    VL5I29O
    Figure 52. Transmitting output adjustment.
    66
    GAIN, set the control for the direction under test to 50 and set the other control to 0.
    (2)	Patch the output of the oscillator to the input of the attenuator.
    (3)	Set the attenuator for a loss of 25 db.
    (4)	Patch the output of the attenuator to jacks E DIR FILT LINE when testing the E-W direction of transmission, or to jacks W DIR FILT LINE when testing the W-E direction of transmission.
    (5)	Patch W DIR FILT LINE when testing the E-W direction of transmission, or jacks E DIR FILT LINE when testing the W-E direction of transmission, to the input of the transmission measuring set.
    (6)	Adjust the oscillator for an output of 0 dbm at 6,000 cycles when testing the W-E direction of transmission or at 8,000 cycles when testing the E-W direction of transmission.
    (7)	Read the transmission measuring set and determine the gain of the repeater.
    Requirement: The maximum gain of the repeater in each direction of transmission should be within ±2.5 db of the value as given in table IX with the gain control for the direction under test set to 50.
    (8)	If the requirement is not met, see paragraphs 101 and 104.
    (9)	Set the gain control for the direction under
    test to steps 40, 30, 20, and 10 and record the gain of the repeater on each of the steps. It is necessary to reduce the setting of the attenuator in order to obtain a reading on the transmission measuring set for the lower settings of the gain control.
    (10)	Note the differences between the repeater gain obtained with the gain control set on 50 and the repeater gain obtained on each of the other steps.
    Requirement: The reduction in repeater gain for various settings of the gain control as compared to the gain obtained with the gain control set to 50 should be within ±1.0 db of the values given in table IX.
    (11)	Remove patching cords, set the controls to the operating positions, and restore the circuit to normal.
    (12)	Repeat the procedure given in (1) through (11) above for the other direction of transmission.
    Table IX. Repeater gain for various settings of controls E-W GAIN or W-E GAIN
    Control	Gain on step	Reduction in gain with control set on
    	50	40	so	20	10	0
    E-W GAIN	31	10	20	30	40	50
    W-E GAIN	32	10	20	30	40	50
    PATCH INPUT
    x DIRECTION	PATCH JACKS OUT OF TRANSMISSION
    OF SETTING OF CONTROLS OF ATTENUATOR MEASURING SET OSCILLATOR TRANSMISSION »-E GAIN E-W GAIN TO JACKS	TO JACKS FREQUENCY
    WEST TO EAST	50	0	W DIR FILT LINE	E DIR FILT LINE	6,000 CYCLES
    EAST TO WEST	0	50	E OIR FILT LINE	W DIR FILT LINE	8,000 CYCLES
    REQUIREMENT: THE MAXIMUM REPEATER GAIN SHOULD BE WITHIN ±2.5 08 OF THE VALUES GIVEN BELOW___________
    CONTROL GAIN ON STEP
    M
    E-W GAIN	31
    W-E GAIN	32
    Figure 53, Repeater gain measurement.
    U5I297
    53. System Line-up
    a. General, (1) The system line-up provides a means for adjusting the outputs of the repeaters and the terminals so that maximum performance is obtained, The system is lined up in each direction of
    transmission from the transmitting terminal through each repeater to the receiving terminal.
    (2) For radio link operation, the system line-up is made for the transmitting and receiving terminals of both carrier channels after the radio transmitters and receivers are adjusted.
    e OR W	W OR E
    OIR FILT	OIR FILT
    LINE	LINE
    OUTPUT	tN	OUT	r~	IN
    ____ H	___ TRANSMISSION
    OSCILLATOR o g>±	ATTENUATOR *	* CARRIER * WOzXg o MEASURING
    REPEATER	SET
    O DBM	25 DB
    67
    b. Apparatus Required:
    At each terminal
    1 Audio Oscillator TS-379/U.
    1 Decibel Meter TS-399/U. Patching cords.
    At each repeater
    1 Decibel Meter TS-399/U.
    1 Attenuator TS-402/U. Patching cords.
    c.	Procedure at Transmitting Terminal (fig. 54). (1) Check, and if necessary adjust the transmittingoutput (par. 51).
    (2)	If switch EQPT is on the 2W position, patch the output of the oscillator to jacks 2W HYB. If switch EQ PT is on the 4W TEL position, patch the output of the oscillator to jacks MOD IN.
    (3)	Adjust the oscillator for a frequency of 1,000 cycles at an output of 0 dbm for an equipment switch setting of 2W, or 4-4 dbm for an equipment switch setting of 4W TEL.
    d.	Procedure at First Repeater (fig. 54). (1) Patch jacks W DIR FILT LINE for the E-W direction of transmission, or jacks E DIR FILT LINE for the W-E direction of transmission, to the input of the attenuator.
    (2)	Set the attenuator for a loss of 10 db.
    (3)	Patch the output of the attenuator to the input of the transmission measuring set.
    (4)	Read the transmission measuring set and determine the repeater output.
    (5)	Adjust the gain control for the direction of transmission under test until the repeater output toward the receiving terminal is within ±1.5 db of the specified output.
    (6)	If no repeater output is specified, adjust the gain control for the direction of transmission under test to give a repeater output between -{-14.5 and 4-17.5 dbm.
    (7)	Record the setting of the gain control for future reference.
    (8)	Remove patching cords.
    e.	Procedure at Succeeding Repeater (fig. 54). Repeat the procedure given in subparagraph (d) above for the succeeding repeater.
    f.	Procedure at Receiving Terminal for Two-wire Termination (fig. 55). (1) Patch jacks 2W HYB to the input of the transmission measuring set.
    (2)	Read the transmission measuring set and adjust control REC GAIN until the transmission measuring set reads within ±1.5 db of the specified circuit net loss.
    (3)	If no circuit net loss is specified, adjust control RFC GAIN for a reading between —4.5 and —7.5 dbm.
    (4)	Record the circuit net loss and the setting of control REC GAIN for future reference.
    (5)	Remove the patching cords.
    g.	Procedure at Receiving Terminal for Four-wire Termination (fig. 55).	(1) Patch
    jacks DEM OUT to the input of the transmission measuring set.
    (2)	Read the transmission measuring set and adjust control REC GAIN to give an output as close as possible to -j-4 dbm as read on the transmission measuring set.
    (3)	Record the output and the setting of control REC GAIN for future reference.
    (4)	Remove the patching cords.
    (5)	Have the transmitting terminal remove test equipment and patching cords, and restore the circuit to normal.
    h.	Procedure for Other Direction of Transmission. Repeat the procedure given in c through g above for the other direction of transmission.
    54.	Loop Gain Measurement
    After the system line-up has been completed for both directions of transmission, loop gain measurements are made at all repeaters and terminals. If the loop gain measurements do not meet the requirements, the gains are reduced until the requirements are met and then the over-all system line-up, as given in paragraph 53, is repeated.
    a.	Apparatus Required:
    1 Audio Oscillator TS-379/U.
    1 Decibel Meter TS-399/U.
    1 Attenuator TS-402/U.
    Patching cords.
    b.	Procedure at Repeater. (1) Measure the actual working repeater gain in each direction of transmission by following the procedure given in paragraph 52Z?(2) through (7).
    (2)	Add the two gains, as measured in (1) above, to determine the loop gain of the repeater.
    Requirement: The loop gain of a repeater should not exceed 45 db.
    (3)	If the requirement given in (2) above is not met, decrease the gain in each direction an equal amount to meet the requirement. Repeat the system line-up for both directions of transmission so as to meet the loop gain requirements at each repeater and receiving terminal.
    c.	Procedure at Terminal. (1) Measure the
    68
    actual transmitting and receiving gains for the working settings of the gain controls by following the procedure given in paragraphs 49&(2) through (7) and 50&(2) through (7).
    (2)	If the circuit is terminated on a four-wire basis, record the working transmitting and receiving gains for future reference.
    (3)	If the circuit is terminated on a two-wire basis, add the two gains as measured in (1) above to determine the loop gain of the terminal.
    Requirement: The loop gain of a terminal should not exceed 26 db.
    (4)	If the requirement is not met, decrease the receiving gain, thereby increasing the circuit net loss, until the requirement is met.
    (5)	Record the final setting of control REC GAIN and the circuit net loss for future reference.
    (6)	Remove the patching cords.
    55.	Synchronization Adjustment
    The synchronization adjustment provides a means for synchronizing the carrier supplies of the two terminals. Since the same oscillator supplies the carrier frequency for both modulation and demodulation at each terminal, the synchronization adjustment is only made at one terminal.
    a.	Apparatus Required:
    1	Audio Oscillator TS-379/U.
    1	Test Set TS-190/U.
    Patching cords.
    b.	Procedure for Wire Operation (fig. 56). (1) Distant Terminal.
    (a) After noting the setting of switch EQ PT, set the switch to the 2W position.
    (&) Insert a patching cord plug into jacks 2W HYB so as to open the circuit.
    (2) Terminal Under Test, (a) After noting the setting of switch EQ PT, set the switch to the 2W position.
    (&) Patch the output of the oscillator to jacks 2W HYB.
    (c)	Adjust the output of the oscillator to 0 dbm at 1,000 cycles.
    (d)	Connect the test receiver to terminals 3T and 8T of hybrid coil HYB.
    (e)	Listen in the receiver for beats between the 1,000-cycle test tone from the oscillator and the demodulated test tone returning from the distant terminal.
    Requirement: The number of beats heard in the test receiver should not exceed eight per second. The number of beats heard per second is twice the difference of the carrier frequencies between the terminals.
    f*----------TRANSMITTING TERMINAL---------------........................................................ ...................REPEATER------------------------------------------
    2W HYB	E OR W
    OR	DIR FILT
    MOD IN	LINE
    ___________OUTPUT_________________———I	_________________________________________OUT___in________________________ __________________________________ H		 H	____ ______________________ ___________________ TRANSMISSION! OSCILLATOR ° fXzj IE;_____________CARRIER	LINE_____________________________CARRIER *	* ATTENUATOR * a—o MEASURING I
    V TERMINAL ------------------------------------------ REPEATER	; V	(Q	SET
    _________ __________________________________________________ 10 00
    PATCH OSCILLATOR OSCILLATOR	DIRECTION PATCH JACKS IN ADJUST	REQUIREMENT:
    SWITCH EQPT OSCILLATOR OUTPUT LEVEL FREQUENCY	Of OF ATTENUATOR GAIN	REPEATER OUTPUT SHOULD BE WITHIN
    ON TO JACKS__________________________	TRANSMISSION TO JACKS CONTROL	tl .5 08 OF SPECIFIED OUTPUT
    2W	2W HY8 0 DBM 1,000 CYCLES	WEST TO EAST E DIR FILT LINE M-E GAIN
    UW TEL MOO IN + U DRM 1,000 CYC1 FS	EAST To WEST W DIR FILT LINE E-W GAIN
    U—----------------------------------------- —	-.'L5I299
    Figure 54. System line-up, repeater.
    69
    Figure 56. Synchronization adjustment, wire operation.

    Hf———TRANSMITTING TERMINAL------------------«»j	-----------RECEIVING TERMINAL--------------
    2W HYB	2W HYB
    0R	OR
    M0D IN___________ OEM OUT
    OUTPUT	—————	-------------
    ncruiATAoO	f->—r. v____	H---------------------------------H	____ . TRANSMISSION
    0SCILLAT0Ro	v--- CARRIER ________________LINE	CARRIER	*	| ® MEASURING
    (Q	TERMINAL	"	TERMINAL	SET
    f------------W-----r—------------------ PATCH INPUT OF
    ..ITCH capt AQAni .TAO An™,'tUT0R OSCILLATOR	SWITCH EQPT TRANSMISSION ADJUST REQUIREMENT
    VITCH EQPT OSCILLATOR OUTPUT LEVEL FREQUENCY	ON	MEASURING SET GAIN
    UH______T0 JACKS___________________	_____________TO JACKS CONTROL__________
    ----—-------2W_HYB.	0 DBM 1,000 CYCLES	2W	2W HYB REC GAIN WITHIN ±I.5DB MW TEL MOD IN +U DBM 1,000 CYCLES	OF SPECIFIED
    --------------------------------------- CIRCUIT NET
    ____________________________LOSS.______
    MW TEL DEM OUT REC GAIN +H DBM
    TL5I299
    Figure 55. System line-up, receiving terminal.
    (/) If the requirement is not met, unscrew the dicated at one or at both terminals. In this event, fiber tube on transformer OSC one turn (fig. 28).	perform the oscillator frequency adjustment at each
    With the aid of a screwdriver, adjust the screw in-	terminal (par. 110) and repeat the procedure given
    side the fiber tube until the requirement is met. in 6(1) and (2) (a) through (/) above.
    Only a small adjustment of the screw normally is (i) Remove the test receiver, oscillator, and patch-required. Tighten the fiber tube after the adjustment ing cords; restore switches EQPT at both terminals is made.	to the operating positions.
    (4CS>	 CONNECTED EQUIPMENT FILTER ,,WF LTC 170-1	 TARR HR 1- 70-1 wmc.F VFR 1. 7A ,EN MFR 1-7A	 LFB—		 1 FRN				 PH LF BN					H CARRIER PAIR LINE CONNECTIONS per tm 11- 2025	 figure	Go		 CARRIER CONNECTIONS per tm 11~ 2025	 FIGURE GO		 VOICE CIRCUIT CONNECTIONS PER TM 11- 202 5	 FIGURE GO	 NON H CARRIER SIDE CIRCUIT PER X	/		 TABLE		 PHANTOM CIRCUIT CONNECTION r PER X		 TABLE
    C-DESIGNATION CARD FOR CARRIER FILTER F-36/FC
    TLSlSie
    Figure 59. Designation cards for type H carrier equipment.
    73
    Date	TERMINAL
    	Control settings
    	TR GAIN	REC GAIN
    1 Mar 45	44	22
    15 Mar 45	44	23
    22 Mar 45	43	23

    	REPEATER
    	Control	Settings
    Date	W-E GAIN	E-W GAIN
    1 Mar 45	40	38
    15 Mar 45	41	39
    22 Mar 45	41	38

    Figure 60. Typical record of control settings.
    c. Trouble Records. Records should be kept of reported and routine troubles which develop. Such records will serve as a basis for scheduling the frequency of routine checks of performance and preventive maintenance. Forms for recording such data may be improvised and will vary with the type of office, personnel, and organization. Figure 61 is a suggested trouble-record form.
    58.	Equipment Performance Checks
    Equipment performance checks must be made at periodic intervals, as shown in table X below, to insure optimum system performance.
    Table X. Equipment Performance Check List.
    Tests	Frequency of test	Paragraph reference
    Terminal:
    Voltage adjustments	Every 4 months	Par. 46.
    Vacuum tube test	Monthly	Par. 47.
    Transmitting output adjustment	Annually	Par. 51.
    Repeater:
    Voltage adjustments	Every 4 months	Par. 46.
    Vacuum tube test	Monthly	Par. 47.
    Over-all system:
    System line-up	Annually	Par. 53.
    Loop gain measurement	Annually	Par. 54.
    Channel net loss measurement	Weekly	Par. 59.
    Synchronization adjustment	Annually	Par. 55.
    Channel net loss-frequency test	Annually	Par. 56.
    59.	Channel Net Loss Measurement
    After the system has been placed in service, measurements are made to check the channel net loss. The channel net loss measurement is made by sending 1,000-cycle testing power from the transmitting terminal and measuring the received testing power at the receiving terminal. The procedure then is repeated for the other direction of transmission.
    a.	Apparatus Required:
    1	Audio Oscillator TS-379/U.
    1	Decibel Meter TS-399/U.
    Patching cords.
    b.	Procedure at Transmitting Terminal (fig. 62). (1) If switch EQPT is on the 2W position, patch the output of the oscillator to jacks 2W HYB. If switch EQPT is on the 4W TEL position, patch the output of the oscillator to jack MOD IN.
    (2)	Adjust the oscillator to a frequency of 1,000 cycles at an output of 0 dbm for an equipment switch setting of 2W, or -f-4 dbm for an equipment switch setting of 4W TEL.
    c.	Procedure at Receiving Terminal for Two-wire Termination (fig. 62). (1) Patch jacks 2W HYB to the input of the transmission measuring set.
    (2) Read the transmission measuring set.
    Requirement: The reading on the transmission measuring set should be within ±1.5 db of the specified channel net loss.
    (3) If the requirement is not met, but the reading of the transmission measuring set is within ±4.0 db of the specified value, adjust control REC GAIN
    TROUBLE RECORD
    Date	Time	Reported by	Report	Disposition	Date	Time	Cleared by
    1 May 45 9 May 45	1000 1610	WWE LH	H carrier system 1. Can’t talk. H carrier system 2. No transmission.	Loose connection contact 3 of TR GAIN. Tube OSC defective.	1 May 45 9 May 45	1015 1620	WWE LH
    Figure 61. Typical trouble record.
    74
    until the requirement is met. If the reading of the transmission measuring set exceeds the specified value of channel net loss by more than ±4.0 db, perform the system line-up (par. 53).
    d. Procedure at Receiving Terminal for Four-wire Termination (fig. 62). (1) Patch jacks DEM OUT to the input of the transmission measuring set.
    (2) Read the transmission measuring set.
    Requirement: The output should be between —J-2.5 and +5.5 dbm.
    (3) If the requirement is not met, but the output
    is between 0 and +8 dbm, adjust control REC GAIN until the requirement is met. If the output is less than 0 dbm or greater than +8 dbm, perform the system line-up (par. 53).
    (4) Remove the patching cords.
    (5) Have the transmitting terminal remove test equipment and patching cords and restore the circuit to normal.
    e. Procedure for Other Direction of Transmission. Repeat the procedure given in b through d above for the other direction of transmission.
    Section VII. OPERATION UNDER UNUSUAL CONDITIONS
    60. Operation under Extreme Weather Conditions
    The operation of an H carrier system under extreme weather conditions, such as sleet, fog, heavy frost, dust or sand storms, and blizzards, generally results in poor transmission unless steps are taken to compensate for the effects of the weather. The effects of extreme weather conditions upon system performance together with suggested remedial measures are given below.
    Weather condition	Effect on system	Remedy
    Sleet Freezing rain Fog Heavy frost	Increased Loss	Increase gain at repeater and receiving gain at terminals.
    Dust storms Sand storms Blizzards	Static noise	Remove telegraph circuit; ground CX or SX telegraph connections.
    61. Operation over Facilities Other Than Open-Wire
    The operation of an H carrier system over facilities
    other than open wire is not recommended except for emergency purposes. Since equalization equipment is not included, the quality of the circuit is degraded so that telegraph transmission normally cannot be used over facilities other than open wire. The use of type H carrier repeaters is not recommended for operation over facilities other than open wire. The maximum terminal-to-terminal operating distances for the more common facilities other than open wire are given below.
    Line facility	Maximum terminal-to-terminal operating distance
    Wire W-143	10 miles.
    Cable, nonloaded, paper	7 miles.
    insulated*
    Cable, spiral four*	30 miles.
    * Because of crosstalk difficulties, only one carrier system should be operated over any one cable.
    62. Operation under Emergency Conditions
    In the event of a major power failure or the demolition of a repeater station, the following emergency operating methods may be used:
    -----------TRANSMITTING TERMINAL----------------H	H--------------RECEIVING TERMINAL	H
    2W HYB	2W HYB
    OR	„ 0R
    MOD IN_____________ _________________________________________DEM OUT
    OUTPUT	'N______________
    H	______________________________ H	____ TRANSMISSION
    OSCILLATOR 2	v	CARRIER	LINE	CARRIER --------* j±° MEASURING
    * TERMINAL ---------------------------------------- TERMINAL	-1 SET
    PATCH OSCILLATOR	PATCH INPUT OF
    SWITCH EQPT OSCILLATOR OUTPUT OSCILLATOR	SWITCH tQPT TRANSMISSION
    OH	TO JACKS LEVEL FREQUENCY	ON MEASURING SET	REQUIREMENT
    2W	2W HYB 0 DBM 1,000 CYCLES	______________TO_JACKS-------------------------—
    ' ' W r------ftoTiiT" +■> DBM, FooFcYCLEs'	2*	2*HYB W7Tcun'NE?BL00SSS|,EC'FI“
    NW TEL OEM OUT ' BETWEEN +2.6 ARD +6.5 DBM
    TLtIJIS
    Figure 62. Channel net loss measurement.
    75
    a.	In the event that a repeater requires extensive repairs, system service can be maintained if another type H carrier repeater is available by proceeding as follows:
    (1)	Using a patching cord, patch jacks W DIR FILT LINE of the available repeater to jacks W LINE FILT of the inoperative repeater.
    (2)	Using a second patching cord, patch jacks E DIR FILT LINE of the available repeater to jacks E LINE FILT of the inoperative repeater.
    (3)	Set the gain controls of the available repeater to the operating settings of the inoperative repeater.
    b.	In the event of a major power failure at a re
    peater station, system service can be maintained by proceeding as follows:
    (1)	Using a patching cord, patch jacks W DIR FILT LINE to jacks E DIR FILT LINE.
    (2)	Increase the receiving gain at the terminals keeping sufficiently below the singing point.
    c.	In the event of the demolition of a repeater and another type H carrier repeater is not available, system service can be maintained by proceeding as follows:
    (1)	Connect the East line directly to the West line.
    (2)	Increase the receiving gain at the terminals keeping sufficiently below the singing point.
    Section VIII. SUMMARY OF PROCEDURE FOR PLACING EQUIPMENT IN SERVICE
    63.	Summary of Procedure for Placing Equipment in
    Service
    This summary applies to Carrier Terminal OA-13/FC, Carrier Repeater OA-IO/FC, and Carrier Filter F-36/FC.
    Step	Action	Text reference
    1.	Mount panels in cabinet or
    	improvised rack		Par. 27.
    2.	Make ground connection to each panel and power connection to terminal
    	and repeater panels...,	Par. 30 through 31.
    Step	Action	Text reference
    3.	Make preliminary tests
    	and adjustments			Par. 32 through 36.
    4.	Interconnect to associated
    	equipment		Par. 37 through 41.
    5.	Make check of system per-
    	formance		Par. 42.
    6.	Perform detailed tests, adjustments, and system line-up at the earliest time service conditions
    	permit		Section V.
    PART THREE
    PREVENTIVE MAINTENANCE
    Section IX. PREVENTIVE MAINTENANCE TECHNIQUES
    64.	Meaning of Preventive Maintenance
    Preventive maintenance is defined as a systematic series of operations performed periodically on equipment in order to maintain top efficiency in performance, to minimize unwanted interruptions in service, and to eliminate major break-downs. To appreciate the meaning of the term preventive maintenance, it is necessary to distinguish between preventive maintenance and trouble shooting and repair. The primary function of preventive maintenance is to prevent break-downs and the consequent necessity for repair. The primary function of trouble shooting and repair is to locate and correct existing defects. The importance of preventive maintenance cannot be over-emphasized. The usefulness of the entire communication system depends upon the equipment being ready to operate at peak efficiency when needed. Preventive maintenance on most parts of this equipment is performed without removing it from service. Care must be taken not to interfere with operation.
    Note. The operations in this section and section X, preventive maintenance check list, are second echelon (organization repairmen) maintenance. The operations in section XII, moistureproofing and fungiproofing, are higher echelon maintenance.
    65.	Description of Preventive Maintenance Techniques
    a.	General. Most of the electrical parts used in this equipment require routine preventive maintenance. Those requiring maintenance differ in the amount and kind required. Because maintenance technique cannot be applied indiscriminately, definite and specific instructions are needed. This section of the manual contains this type of 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*
    I —Inspect
    T—Tighten C—Clean A—Adjust* 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 requirements. For example, dust filters into the equipment no matter how much care is taken to prevent it. Rapid changes in climatic conditions (such as heavy rains followed by blistering heat) or excessive dampness, snow, and ice tend to cause deterioration of exposed surfaces and parts.
    b.	Inspect (I). Inspection is the most important of all the preventive maintenance operations. If more than one man is available to do this work, choose the most observant, for careful observation is required to detect defects in the functioning of moving parts and any other abnormal conditions. To carry out the inspection operation most effectively, make every effort to become thoroughly familiar with normal operating conditions and to be able to recognize and identify abnormal conditions readily. Inspection consists of carefully observing all parts in the equipment, noticing their color, placement, cleanliness, etc. Inspect for the following conditions:
    (1)	Overheating. Overheating is indicated by discoloration, blistering, or bulging of the part or surface of the container; leakage of insulating compounds; and oxidation of metal contact surfaces.
    (2)	Placement. See that all wires and cabling are in their original positions.
    (3)	Cleanliness. Examine carefully all recesses
    * The Feel, Adjust, and Lubricate operations are inapplicable to this equipment.
    76
    77
    in the units for accumulated dust, especially between connecting terminals and contacts. 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. Gently test for movement any connection or mounting which appears to be loose. Feel the lug or tetrminal screw.
    c.	Tighten (T). Any movement of the equipment caused by transportation, by concussion, or by vibration from moving machinery may result in loose connections and mountings which are likely to impair the operation of the equipment. The importance of firm mountings and connections cannot be overemphasized ; however, never tighten screws, bolts, and nuts unless it is known definitely that they are loose. Fittings that are tightened beyond the pressure for which they are designed will be damaged or broken. When tightening, always be certain to use the correct tool of the proper size. If a screw does not turn easily, remove it and begin again.
    d.	Clean (C). (1) When the schedule calls for cleaning, it does not mean that every item which bears that identifying letter must be cleaned each time it is inspected. Clean parts only when inspection shows that it is necessary.
    (2) Items such as vacuum tubes, capacitors, resistors, coils, etc., are cleaned by wiping with a clean, lint-free, dry cloth or by brushing. It may be necessary in some cases to use cleaning fluid to remove dirt. Apply it with a cloth or brush and wipe dry with a clean cloth. Remove corrosion by rubbing lightly with fine sandpaper.
    Note. Gasoline will not be used as a cleaning fluid for any purpose. Solvent, Dry Cleaning, is available as a cleaning fluid through established supply channels. Oil, Fuel, Diesel, may be used for cleaning purposes when dry-cleaning solvent is not at hand. Carbon tetrachloride will be used as a cleaning fluid only where specified for cleaning contact parts of electrical equipment, or as specified where inflammable solvents cannot be used because of the fire hazard. Oil, Fuel, Diesel, zvill not be used for cleaning electrical contacts.
    (3) Clean switch contacts and jack spring contacts by drawing a burnishing blade between two contacts held together gently with the fingers. If excessive dirt is present, flush the contacts by dipping a toothpick in carbon tetrachloride and applying it between the contacts, or dip the burnishing blade in carbon tetrachloride and then draw it between the contacts. After the application of carbon tetrachloride, draw a piece of bond paper between the contacts. Clean the burnishing blade with a dry, lint-free cloth and burnish the contacts again.
    66. Preventive Maintenance of Classes of Parts
    This section of the manual does not deal with each tube, each resistor, or each capacitor of the equipment. Rather, it combines all the instiuctional material on the major classes of parts and devices. If abnormalities cannot be corrected by following these instructions, see the appropriate repair instructions for corrective action.
    a. Vacuum Tubes and Sockets.
    Caution: Preventive maintenance on these items should be performed only when the tubes are removed for periodic check.
    Preventive maintenance for vacuum tubes includes inspection and cleaning. Preventive maintenance for tube sockets and mountings involves inspection, tightening, and cleaning. Each of these operations will be discussed in detail below.
    Caution: Care must be taken in working on tubes. Severe burns may result from contact with the envelopes of hot tubes.
    (1) Inspect (I), (a) Examine glass tube envelopes, tube caps, and tube connector clips for the accumulation of dirt and for corrosion. Watch for tube caps which have broken away from the cement that attaches them to the glass envelopes, and for tube envelopes that have broken away from the tube base. When tubes have loose grid caps or envelopes, they should be replaced if possible. If suitable replacements are not available, repair should not be attempted; but a record should be kept so that replacement will be made at the earliest opportunity.
    (b)	Examine the spring clips that make contact with the grid caps for corrosion and for loss of tension with resulting looseness. Check the condition of the wires soldered to the spring clips. The wires must be free of frayed insulation and broken strands. I he removal of connecting clips from loose grid caps must be done with great care, particularly if signs of corrosion exist. Never turn a clip if it is on a loose cap.
    (c)	Determine the firmness of tubes in their sockets by inspection. Make the inspection by pressing the tubes down in the sockets and testing them in that position, and not by partly withdrawing the tubes and jiggling them from side to side. Movement of a tube tends to weaken the pins in the base and unnecessarily spreads the contacts in the socket; trouble will occur where it did not exist before.
    (d)	Be careful when removing a tube from its socket. A warm tube must never be jarred. Connections to the grid cap must always be removed. It is important to store tubes carefully after they have
    78
    been removed from the sockets. They should not be placed on elevated flat surfaces without proper precautions to prevent their rolling to the floor. They are not to be placed on the floor where they might be kicked or stepped upon.
    (e)	Inspect tube prongs for dirt and corrosion.
    (2) Tighten (T). Socket mountings must be tight at all times. Otherwise, during transit they will be loosened, and the tubes in them may become irreparably damaged. When tightening bolts that hold the sockets to the panel, do not apply excessive pressure. Too much pressure will crack the insulating bushing. Tighten tube connector clips by pressing with the fingers. Do not flatten the clips, since flattened clips do not make adequate contact with the surface of the tube cap.
    (3) Clean (C). Clean the tubes, but only if inspection shows cleaning to be necessary. These tubes do not require frequent cleaning. The cleaning of tubes calls for the removing of dust and dirt from the glass envelopes with a cloth, and the removal of dirt and corrosion from the tube prongs by rubbing lightly with a piece of fine sandpaper. Clean the grid caps by wrapping a piece of fine sandpaper around the cap, and rubbing gently along the surface. Excessive pressure is not needed; neither is it necessary to grip the cap tightly.
    b.	Capacitors and Filters. (1) Inspect (I). Inspect the terminals for corrosion. Inspect the mountings for loose mounting screws, studs, or brackets. The terminals should not be cracked or broken. The case of each capacitor must be thoroughly inspected for bulges, discoloration, and dirt.
    (2)	Tighten (T). Tighten loose terminals and mounting.
    (3)	Clean (C). Clean the case and the insulating bushings.
    c.	Resistors. (1) Inspect (I). Inspect the coating of vitreous resistors for signs of cracking and chipping, especially at the ends. Examine the bodies of all types of resistors for dirt and blistering, discoloration, and other indications of overheating. Also look for arc pits or craters. 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.
    (2)	Tighten (T). Tighten loose resistor mountings. If a resistor is allowed to remain loose, vibration may break the connection or damage the body.
    (3)	Clean (C). Remove all dirt, dust, and corrosion. ' Resistors with discolored bodies cannot be cleaned. Discoloration is indicative of overloading at
    some time prior to the inspection and is probably due to circuit trouble, which requires analysis.
    d.	Switches and Controls.
    Caution: Do not move switches or controls since the slightest movement may impair operation and service. The gang switch contacts can be examined only when the switch panel is disassembled. If it is disassembled for repair, inspect mechanical action by turning the knobs and noting the freedom of movement, spring tension of contacts, and accumulations of dirt, dust, or corrosion on the contacts. Clean exposed parts and contacts if dirty.
    (1)	Inspect (I). Inspect for cleanliness and looseness of knobs and mounting.
    (2)	Tighten (T). Tighten all loose mounting screws.
    (3)	Clean (C). Clean the exterior surfaces with a stiff brush and wipe with a piece of cloth.
    e.	Jacks. Jacks require very little attention, and only at infrequent intervals. Since these jacks are inaccessible unless the switch panel is disassembled, preventive maintenance will be performed only when it is necessary to disassemble the switch panel for repairs.
    (1)	Inspect (I). Inspect for loose mounting, dirt, and corrosion. Observe the mechanical action of the jack springs by inserting and removing a cord Plug.
    (2)	Tighten (T). Tighten loose mounting and spring assembly screws.
    (3)	Clean (C). Remove surface dirt with a brush and dry-cleaning fluid, and clean the contacts.
    f.	Transformers and Coils. (1) Inspect (I). Inspect for general cleanliness and tightness of connecting lugs or terminals, mounting brackets, and rivets. Dust, dirt, or moisture between the terminals of high-voltage transformers or on coils located at high-potential points in the circuit may cause flashovers.
    (2)	Tighten (T). Tighten loose mounting screws.
    (3)	Clean (C). Clean the cases of transformers and coils.
    g.	Wiring, Cabling, and Cords. These items are regarded as the life lines of the equipment. Their condition must be closely observed.
    (1)	Inspect (I), (a) Inspect insulation for cracking, deterioration, fraying, and cutting, especially at connecting and supporting points. Check for improper placement which causes strain, particularly at connections. Watch for kinks and improper supports.
    (b) Inspect all connections for tightness. The ground connections should be observed very closely. If any one of the grounded points is open, it may in
    79
    terfere with operation of the equipment and no protection is afforded to the operating personnel.
    Caution: If any loose ground connections are observed, they should be tightened immediately. If practicable, remove the equipment from service and disconnect the power supply.
    (2)	Tighten (T).	(a) Tighten loose cable
    clamps, wiring rings, and screw connections.
    (b)	Resolder all loose or improperly soldered connections.
    (c)	Cut off frayed strands of insulation. If wire is exposed, wrap it with friction tape.
    (3)	Clean (C). Clean prongs of cord plugs and connections when they are dirty or corroded. Scrub with a brush dipped in dry-cleaning fluid,
    and dry thoroughly with a cloth. Remove corrosion by rubbing lightly with fine sandpaper.
    h.	Terminal Strips and Panels. (1) Inspect (I). Inspect for scratches, cracks, breakage, dents, excessive dirt or dust conditions, fungus growth, and loose mountings.
    (2) Tighten (T).' Tighten loose mounting screws.
    (3) Clean (C). Clean by brushing or wiping with a dry cloth.
    67. Preventive Maintenance Tools and Materials
    The tools and materials required for performing preventive maintenance are furnished in the office tool sets which must be ordered separately.
    Table XI. Preventive maintenance tools and materials
    Mfr’s, part No.	Signal Corps stock No.	Nomenclature	Usage
    KS-8740, List 2 P-294472 R-2120 R-6433	6R24626 6N7531.2 6R4748-6.5 6Q29928	Soldering copper, electric, with KS-8740, List 3IB, tip, 2%" Solder, rosin core, 0.070" Pliers, long-nose, 6" Pliers, diagonal, V-notch, 5"	Repairing poor or loose connections.
    KS-6854 90	6R40848/1 6R16021	Screwdriver, 3J^" Screwdriver, regular, 5"	Tighten screws.
    R-1021 KS-2423	6Z1550 6Z7500-0000 6N1624	Brush, flat, stiff, Solvent, dry-cleaning Sandpaper, 150 grade, #0009 Cloth, lint-free	Removing dirt, dust, and corrosion
    RM-591127	6N8583	Tape, friction, %"	Repairing frayed insulation.
    265C 266B KS-7188 RM-717053 KS-6815	6R41065C 6R41066C 6M750 6Z8666 6G184	Burnisher, relay contact Burnisher blade Paper, cleaning Toothpicks Carbon tetrachloride	Cleaning switch contacts.
    —	6R55507	Wrench, socket set, consisting of handle and 6 sockets	Tightening nuts and bolts.
    Section X. PREVENTIVE MAINTENANCE CHECK LIST
    68. Preventive Maintenance Check List
    (These items are second echelon maintenance.
    Item No.	Operations	Item	Subpar, under par. 66	Weekly	Monthly	Semiannually
    1	ITC1	Vacuum tubes and sockets	a		1
    2	ITC	Capacitors and filters	b			X
    3	ITC	Resistors	c			X
    4	ITC	Switches and controls	- d		X
    5	ITC	Jacks	e		X
    6	ITC	Transformers and coils	f			X
    Item No.	Operations	Item	Subpar, under par. 66	Weekly	Monthly	Semiannually
    7	ITC	Wiring, cabling, and cords	£		X
    8	ITC	Terminal strips and panels	h	X
    JThese operations will be performed only when the tubes are removed for periodic check.
    F I T C A	L
    Feel2 Inspect Tighten Clean Adjust2 Lubricate2
    2 The Feel, Adjust, and Lubrication operations are inapplicable to this equipment.
    80
    Section XI. LUBRICATION
    69. Lubrication
    Lubrication of this equipment is not required since there are no moving parts.
    Section XII. MOISTUREPROOFING AND FUNGIPROOFING
    70.	Moistureproofing and Fungiproofing
    a.	General. When operated in tropical areas where temperature and relative humidity are extremely high, Signal Corps equipment requires special attention. These are the problems met:
    (1)	Resistors, capacitors, coils, chokes, transformer windings, etc., fail because of the effects of fungus growth and excessive moisture.
    (2)	Electrolytic action, often visible in the form of corrosion, takes place in resistors, coils, chokes, transformers windings, etc., causing eventual breakdown.
    (3)	Connecting wire insulation and cable insulation break-down. Fungus growth accelerates deterioration.
    (4)	Moisture forms electrical leakage paths on terminal strips and insulating strips, causing flashovers and crosstalk.
    b.	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. Refer to TB Sig 13 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 poisonous effects if inhaled. To avoid inhaling spray, use respirator if available; otherwise, fasten cheesecloth or other cloth material over nose and mouth. Never spray varnish or lacquer near an open flame. Do not smoke in a room where varnish or lacquer is being sprayed. The spray may be highly explosive.
    71.	Sfep-by-S+ep Instructions for Treating Carrier
    Terminal OA-I3/FC
    a. Preparation. Make all maintenance checks,
    repairs, replacements, and adjustments necessary for proper operation of the equipment.
    b. Disassembly. (1) Remove the control knobs by first removing the setscrew on each knob (fig. 63).
    Figure 63. Removal of control knobs.
    (2)	Remove designation card and cover (fig. 64 ®).
    (3)	Remove grid leads from vacuum tubes (fig. 64®).
    (4)	Remove positioning pin from each of the control knobs (fig. 64 @). (These pins are not to be treated.)
    (5)	Remove four mounting screws holding the GAIN controls (fig. 64 @).
    (6)	Remove four panel screws (fig. 64 ®).
    Caution: All screws, washers, and nuts should be replaced in their original positions after being removed. This will prevent their loss, and also the
    I (2) control knobs>
    I (I) SET SCREWSf
    |TL5O453-sJ
    81
    F—--(5) PANEL 'SCREWS'-—"] - ■' ? .
    (2) GRID LEAD	. A. «rtf lMT,^	A■' ’. '	(2) GRID LEADS
    . ।	.'	। (4) MOUNTING SCREWS . <	7
    (• .: x . I	... ' ' .; ; '• *’ ■-'■■’■* ■'■' ■'■ ’. ! ’ I •■ ■ ■ ’ . v ■ •	<» , , ■.. ■ ,	77 .
    if	l' , L L	r<.	" y7 /
    ■' I II o W J J /’ V	‘
    1 ' J	F
    ^Wtibk	UhIeFI
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    ■ ■ -■ I	'•m	\
    -' ' '1'/f~ H S8 ?,	ft	jjjjgHgfc viwe+t	9'	\
    I MjW""1 POSmONINGPlNSjl^
    !	_____ I;	b,
    ---- jfih<
    >S> '■	/	TEMSPIU,:,
    X	)
    (5) PANEL SCREWS i’h^''^1''^'^"'''''l I I
    J* . ’ —
    H CARR TERM	/
    ■ , .	_____' ••' ■ '~' '	, '	• s    •   —
    X	I
    (I)	DESIGNATION CARD HOLDER
    ......	. ’LM4.5idJ
    Figure 64. Disassembly of terminal sub panel.
    clogging of threads, during spraying or varnishing operations. Tighten firmly any screw contacts from which it is not necessary to disconnect leads (for example, the power plug). This will prevent lacquer from getting on the contact surfaces of terminals.
    (7)	Carefully draw the subpanel away from the panel (fig. 65 ®). Take care not to break any of the soldered connections. Handle the subpanel only when necessary, as unnecessary motion may break the soldered connections. Resolder broken connections immediately.
    (8)	Remove the GAIN controls from the subpanel (fig. 65 @).
    Caution: The wires on these controls are short, and are easily broken.
    (9)	Remove nut and lockwasher from cover of each control (fig. 66 Q).
    (10)	Remove cover (fig. 66 ®).
    (11)	Remove four screws from cover plate of each control (fig. 66 @).
    (12)	Remove cover plate (fig. 66 @).
    (13)	Swing bakelite ring clear of control assembly (fig. 66 @).
    c. Cleaning. Clean all dirt, dust, rust, and fungus from the equipment to be processed. Clean all oil and grease from the surfaces to be varnished.
    Note. Unless the cleaning is done carefully and thoroughly, the effectiveness of the moistureproofing and fungi-proofing treatment will be impaired.
    d. Masking. (1) Mask jack field on subpanel (fig. 67 ®).
    (2)	Mask three grid clips (fig. 67 @).
    (3)	Mask three grid caps (fig. 67 @).
    (4)	Mask prongs of power plug (fig. 67 @).
    (5)	Mask tapped holes on GAIN control cover plates (fig. 67 @).
    (6)	Mask the rear sections, containing the switch arms and contacts, of the two GAIN controls (figs. 67 ® and 68 ©).
    (7)	Completely mask the shaft and gear assemblies of the two controls (figs. 67® and 68 @).
    (8)	Completely mask the rear of the jack as-
    82
    Figure 65. Disassembly of terminal panel,
    HI) SUBPANEL
    I DRAWN AWAY FROM I | TERMINAL PANEL |
    1(2) METHOD OF REMOVING -jGAIN CONTROL HHBRHMMK "	"Y’W”’
    ^UL5Q455r£|
    83
    . (I) NUT AND" ■ LOCKWASHER
    Bn
    (4) COVER PLATE Engl yjSh
    4	V
    fi I	.^SSMhk &cover
    U 4|	I
    gM|	»	| jM ; Jte§3 *’ S	B'
    (5) PANEL SCREWsl42 -	I	• t' -z
    /^S^''~~',,^WW!8"'9' ""^w*—*'”' t'" w-^k	j
    -~3BSSEBBM j4) mounting sCREWSjta»EMlj
    ■	1	>1	Mg&
    ■	(I) DESIGNATION
    (3^QPOSITIO NI ng" N S	CARD HOLDER jjjlS'
    'S	l ~ "—-  ? - sffEi®	B'
    rt S5p|W-.-'
    I ... L.,....,.	________________J
    I i r	m
    I- cl I I 1	%
    ??	I I Ik	k” ~~
    Figure 70. Disassembly of repeater panel.
    88
    BTbTsHA^S
    AND GEAR®
    •' •	ASSEMBLYg| . tgr. ^WjL’A
    7?-‘SaV-Y'rS’ltT5!	*•\'	■Tv- • l|SE(7)SvmUH AR MBS#
    ct^SJKi ‘ w	mHBand contacts MBS
    (I) VACUUM TUBeI
    y*'W i )^L in
    '	J(+JACKS^ ;•''	'
    (4) GRID CAPS' IsJ	|L-?
    K	wr*	GHID CL,PS
    jMg^+jpgS
    ■ HCAhKhEP ■•	_____________■	(6)P0WER^
    ■	V m ¥	plug PRONGS|g
    g	I I (5) TAPPED HOLES J ^gjV^
    K"':M^^^0BBs^£ hEpF	TO
    ^B ■!■ ,;	-	-. *-^rMB^r ^aAi^wyWw^wjl ES*
    ^UHk ——»	.^Uvg .	-*’*v..zr U2a&* «	s*W	nlw*-'	.vm- A' J0t*7
    gg	jgs;--S	jjbu' :• -.	~
    GAIN CONTROL COVE^^TESg^..;	.	,
    Figure 71.	Masking of repeater panel, front view.
    I \
    /I	(I) SWITCH ARMS AND CONTACTS	|
    /	(2) SHAFT kBT' '■^.1
    W "•?	/ AND GEAR ' Kil l
    pW	/ ASSEMBLIES WNMMf^ni I
    tCj B. w
    Ik tea* «'Ug!** |;
    V' T'\ " r -1 /n I
    J- ’ A* A ‘ ,i
    FW XiE; « (3) JACK ASSEMBLIES ..	.	. tlso46Fs1
    u- L<."!.'!? . J - gpriMiMI" L
    l F^THii!’ x. i -	t.
    ' ^*A ' • • :
    rs	(I) TUBE SOCKETS	S,t
    W^F"1
    -MKAq1A~
    *>~-±LF 2-	„
    ....................?< 'I ■
    +«gg’iaCjl » Jfg\.Cl TL5046 3 S
    Figure 72.	Masking of repeater panel, top view.
    Figure 73.	Masking of repeater panel, rear view.
    89
    f.	Varnishing. (1) Apply three coats of moistureproofing and fungiproofing varnish (Lacquer, Fungus-resistant, spec No. 71-2202 (stock No. 6G-1005.3), or equal). Allow each coat to air-dry 15 or 20 minutes before applying the next coat.
    (2)	Apply varnish immediately after the equipment is dried. If varnish is not applied immediately, moisture condenses on the equipment. Varnish applied over the moisture peels off readily after the varnish has dried.
    (3)	Spray all of the equipment. Use a brush to apply varnish to those portions not reached by spray. Take special care that all wiring is adequately coated with varnish.
    g.	Reassembly. (1) Apply one coat of varnish with brush to all wires which are unvarnished.
    (2)	No reassembly is required. Test the operation of the panel.
    Note. The electrical characteristics of electronic equipment are subject to change over a period of approximately 10 days after the application of varnish. For this reason it is desirable to wait until this period has elapsed before making the final check.
    h.	Marking. Mark the letters MFP and the date of treatment near the designation H CARR LINE on the front of the panel.
    Example: MFP—11 Mar 45.
    74. Moistureproofing and Fungiproofing after Repairs
    If, during repair, the coating of protective varnish has been punctured or broken, and if complete treatment is not needed to reseal the equipment, apply a brush coat to the affected part. Be sure the break is completely sealed.
    PART FOUR
    AUXILIARY EQUIPMENT
    (NOT USED)
    90
    PART FIVE
    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) ; by Army Air Forces, on Army Air Forces Form 54 (Unsatisfactory Report). If either form is not available, prepare the data according to the sample form reproduced in figure 74.
    Section XIII. GENERAL REPAIR PROCEDURE
    75.	Outline of Repair Technique
    a.	Trouble on the type H carrier system will be detected by routine testing or by a trouble report from the using or operating personnel, noting either faulty operation of the system or a complete failure. The first step in clearing this trouble is to isolate it to a terminal or repeater installation, a line section, or some external portion of the circuit. If the trouble is found to be at an installation it can be further isolated in either the transmitting or receiving branches of the equipment, or in some circuit common to both branches, such as the power supply or the hybrid coil. Voltage measurements in the power supply or amplifiers, or tone tracing in the transmitting or receiving branches, will locate the source of trouble in a particular circuit or piece of equipment. Operational and line-up tests will also aid in locating the source of trouble. Substitution of parts may be necessary when it is impossible to test all the circuits of a component part, a filter, for example.
    b.	When the trouble is located it may be corrected by replacement of a defective part, or by adjustment of a circuit or component. The system will be given a new over-all circuit line-up, its ©Deration tested from end to end, and it will then De restored to service.
    c.	In order to perform the trouble location procedure described above, the maintenance man must have a certain amount of knowledge and skill. His
    knowledge must include the detailed functioning of the equipment. He must know how to read and understand wiring and schematic diagrams. He must be familiar with the testing apparatus to be used in testing the equipment, and know how to apply the information. Skill in the use of maintenance tools will not only result in more efficient operation of the system, but will also reduce the chance of the same trouble recurring. The goals to be attained are accuracy in the location of trouble, skill and efficiency in its repair, and speed in returning the system to service. If the maintenance man has the qualifications listed above, the attainment of these goals is simplified. The following repair instructions will be based on the assumption that the reader possesses the necessary qualifications.
    76.	Unsatisfactory Equipment Report
    a.	When trouble in equipment used by Army Ground Forces or Army Service Forces occurs more often than repair personnel feel is normal, War Department Unsatisfactory Equipment (WD AGO Form 468) should be filled out and forwarded through channels to the Office of the Chief Signal Officer, Washington 25, D. C.
    b.	When trouble in equipment used by Army Air Forces occurs more often than repair personnel feel is normal, Army Air Forces Form 54 should be filled out and forwarded through channels.
    c.	If either form is not available, prepare the data according to the sample form reproduced in figure 74.
    91
    92
    WAR DEPARTMENT
    UNSATISFACTORY EQUIPMENT REPORT
    FOR	TECHNICAL SERVICE	z-S Cowb	MATERIEL		DATE ITT-	i- ~ 5 1
    FROM	ORGANIZATION	—- T 579 Sio.+du>aVL>Oro.		s,.™n APOJ.0I P/lAiyTTi ZUtCJ	Ub]
    TO	NEXT SUPERIOR HEADC s	DARTERS	».	.	STATION	TECHNICAL SERVICE	'	77 V
    		V	'	COMPLETE MAJOR ITEM	>	I
    NO M EN CLAT U	TYPE	-	*		MODEL
    MANUFACTURER JL	I	A. REG. NO. "	SERIAL NO.		DATE RECEIVED 25 Fdr- 4b
    equipment with which used (if applicable)
    DEFECTIVE COMPONENT—DESCRIPTION AND CAUSE OF TROUBLE
    PART NO.	TYPE^t^	- P)	MANUFACTURER	•	Z3
    DESCRIPTION OF failure and probable CAUSE (If additional spate is required, use back of form)	.
    AYOuSaaxGS frCCftfi	IuleHd IaLLW4.dk opfALU(kq eftXX&tlfrVLS
    DATE OF INITIALjTROUB^E	TOTAL TIME INSTALLED	|TOTAL PERIODloF  5,0001	1] filter. in f I T C3 h2h'C2 R5 []]	.
    _ n \z o 1—2 J—	----stVpbs —1'------------------
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    MMF R6 U tp | _____________________________________________________________________________________6500_______________uj_,
    COMMON	*=
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    tq 2.16 MF	2.16 MF Xcil	-------It--—	A to
    to £< HYR	T 2.16 MF	OSC 3,000 MMF	~ ^nVof'
    2-WIRE M	k	6g ?7 J. ------------| OSC	VV LINE
    line ■> <*	|RI2	RH -J-C9 C8 -I- X *	7 o 3	SUPPLY
    I	5 I MEG T* 4 MF 4MF'"' P2 ______________________S g
    1	8 “ ® I
    € ---1 jy X------1--------X------------ ------------ JLPL_J,_____________________
    NOTE	tl sisre
    -L IS SYMBOL FOR FIXED CAPACITOR
    Figure 76. Terminal pozver supply circuit.
    97
    lated voice currents pass directly from transformer REC OUT through jacks DEM OUT and 4W REC to the four-wire line.
    (2)	Switch at 4W TLG. Voice currents enter the terminal through jacks 4W TR and MOD IN and pass directly through the hybrid repeating coil to the modulator circuit. Tn the receiving path the demodulated currents pass directly from transformer REC OUT through jacks DEM OUT and 4W REC to the four-wire line. In normal operation this arrangement is not used, but is provided for cases where disconnection of pad R1 in the transmitting path is desired.
    84.	Terminals Arranged for Radio Link Operation
    When switch LINE is at either of the RADIO positions, the function of the two terminals is basically the same as that described in preceding paragraphs. Two terminals are required, and the directional filters DF, controls REC GAIN, and band-pass filters BF are so interconnected that the transmitting circuits of both terminals are connected to the directional filter of one terminal and the receiving circuits of both terminals to the directional filter of the other terminal (see figs. 8 and 9).
    85.	Transmission Characteristics of Terminal Filters
    Three combinations of filters are used in the terminal circuits: low-pass, band-pass, and directional. Each of these filters is comprised of two units, which are
    sealed in a single metal container and designated as a single item (LP, BF. and DF).
    a.	Low-pass Filter LP (fig. 78). One portion of this filter is used in the transmitting circuit and the other in the receiving circuit. Since less suppression is required in the receiving circuit for frequencies above the voice band, the two units have different characteristics. A simplified schematic diagram of the carrier leak suppression network, housed in the same container with filter LP, is also shown in figure 78.
    b.	Band-pass Filter BF (fig. 79). Each of these units may be switched into either the transmitting or receiving circuit, depending upon whether an East or West terminal arrangement is used. The unit which selects the 4,150- to 6,900-cycle band is actually a low-pass filter since such a structure gives adequate suppression of the unwanted frequencies.
    c.	Directional Filter DF (fig. 80). These units separate the transmitting and receiving paths of the carrier frequency side bands and are arranged to provide attenuation in the high frequency singing path of the terminal with minimum distortion to the transmitted carrier frequency side bands.
    86.	Terminal Transmission Performance
    a. Maximum Transmitting and Receiving Gains. The maximum gain available at a terminal is dependent upon the gain of the amplifiers less the losses inserted by the components of the transmitting and receiving circuits. Since these components vary with the terminating arrangement (two-wire, four-wire) the available gain varies also. The maximum available gains for the various arrangements are shown in table XII. These gains have been computed at a frequency of 1,000 cycles applied to the switchboard side of the terminal. Though there will be slight variations due to manufacturing tolerances, differences in tubes, small changes in the voltage supply, and aging of the varistor units, these gains can be obtained in most cases. The 20-db transmitting gain for the two-wire arrangement can be computed by subtracting the total loss of the components (13 db, composed of 12 db in the modulator circuit, including the hybrid coil, transmitting low-pass filter, modulator, and modulator output transformer, and 1 db in the transmitting band-pass and directional filters) from the amplifier gain (33 db). The 16-db receiving gain can be computed by subtracting the total loss of the components (17.1 db, composed of 2.0 db in the receiving directional and band-pass filters, 4.0 db in the demodulator circuit, including the demodulator input transformer, demodulator, and
    R1	LP
    ax	----- HYB	----
    0 H -------------------------1 1------ -----------
    ---* 4W	TR^ZMOD in	pad	I	LOW‘
    -> <	8 0B	?	J	-	PASS
    H________	______?	T______F'LTER
    REC OUT
    All	--------
    ’—h------------------------------------ifr^
    * 4W REC^^DEM OUT	|	|
    *£--------H-----------------------------J L-------
    SWITCH EQPT ON 4W-TEL	A
    LP
    a,	HYB	----1
    ° H	L XMTC
    ><	1 F	low-
    —- 4W trXZmod in	? Hl	pass
    Ha F filter --------------------1 I------1	------
    REC OUT
    All	I
    °—h------------------------------------i rr=
    ---4W RECDEM OUT	| | §
    *£—-------H----------------------------J | L------
    B
    SWITCH EQPT ON 4W-TLG TL 51574
    Figure 77. Four-wire termination.
    98
    LOSS-OB
    36 ———r——————7——n—————rn—""T
    34 —--------------------------+---------------------------
    32--------------------------------------------------------
    30--------------------------------------------------------
    28---------------------------------------------------—
    26----------------------------------------------—---------
    24-------------------------------------------------
    3 O—  | O—। x r-O-C—O->	rO-O I
    g U LaJ	s
    20 — I n T n-------------------------—z---------------
    4 o—3—oJ	LoJ-o-J	Io—o 2	y	S
    l8-------------------------------J-—jZ—---------------
    TRANSMITTING	\	/
    LOW-PASS FILTER UNIT	\	.f
    i6-- -/
    I-----------------*.	X 11 c——o->	p>—0—o 9
    14 “’---------------------------------- I qoo J	—T—
    12----------------------------1---—AJ—	—
    I	/	\ I2O .j	Lo—|0
    l0----------------------------1-y-------------------------
    I	/	'-----RECEIVING
    f	Z	LOW-PASS FILTER UNIT
    8----------------------------1-f------ ------------------
    6----------------------------£_-------5o--GJUIP—  1(—06 -
    I	S	CARRIER-LEAK
    4 I  S\SUPPRESSION NETWORK
    2------------------------------:-------------------------
    I	234	56789	10
    IS SYMBOL FOR FIXED CAPACITOR FREQUENCY-KILOCYCLES PER SECOND
    TL5I579
    Figure 78. Transmission characteristics of low-pass filter LP.
    99
    3S|--------------------------------- 36-----------------------------------------
    34---------------------1---I-------- 34----------------------11-----------------
    32---------------------I---1---T----	32-----L-----------------------------
    30--------------L—--( —-------------	30----V------------------------------
    9»—I	\	1
    M  »—It—J	| —4- 1  ------------- 28-------------------------,_4<>^>4^3 4 * * * *
    26-- i —I------------------X-------- 26-------------V-----------FT	FT --
    l0u——i-oi2 T V	\ L -----------------h>4
    22---------------------1------------ 22-----------------------------------------
    _ 20---------------------1-------^=~" 1——	20---------------------------------J—
    st	s	/
    -.8----------------------------------- J, .8------------------------------------7 —
    <£>	I	in	/
    5 >6-------—-------------1------------ o 16______________________________J______L_
    4150 - 6,900 0/	|	->	Z400-IQI50O/ /
    M________BAND__________I__________ , .	BAND	f
    f	!------------ 14---------------------------------------y-
    12---------------------1------------ 12-----------------------------------L-----
    10---------------------1------------ 10----------------------------------/------
    xcL- j ; X,£
    ■ ■ 11—»■=»= I	---- -------I_	O'____________ I I
    •	2	3, 4	5	6	7	8	9	10 II 12	13	14	15	I 2	3	4	5	6	7	8	9	10 II 12	13	14	15
    FREQUENCY-KILOCYCLES PER SECOND	FREQUENCY-KILOCYCLES PER SECOND us.sso
    4 IS SYMBOL FOR FIXED CAPACITOR
    Figure 79. Transmission characteristics of band-pass filter BF.
    361———7—r~s—————————irn—————t—————7——————
    34------------1------------------------jp--------y/-------------J---------------
    32------------4----------------------------------yZ-------------/---------------
    30------------\------------t-----------1-------y-------------1——————— — —
    28--------------1------------------------1-Z-----------------J------------------
    26--------------L-----------\—/_---------------—-------------_/-----------------
    24--------------\------------:-------------------------------Z-->---------------
    22--------------1-----------------------------------:--------1-----2------------
    m 20--------------A-----------------—--------------------------/------------------
    °	\	/
    CO 10--------------T	------------T--—-----------------
    tO	\	/
    O 16---------------------L-------------------------— — [---------------~----------
    14---------------------1.------------------—------------------------------------
    \	TRANSMITTING	RECEIVING	j 3°——\
    *----------------------V-----rr----------------t~t-------i, Q i™T°
    8	t ————————— — ———	j— ^o-ojTir<>d(Y<>yT'®rM>jf<8<>Gnnr<>4f*<>Gnnr'<>-|(> \ | -p
    6-----------------\------------------l---------------/ g j iRcvG/ 2
    4-------------------k---------------1—---------------+------------r-----------
    2--------------------+------------------© --X--—------------------------------
    I	2	3	4	5	6	7	8	9	10 il 12	13	14	15
    £ IS SYMBOL FOR FIXED CAPACITOR	FREQUENCY-KC	TLJIJSI
    Figure 80.' Transmission characteristics of directional filter DF.
    100
    receiving low-pass filter, 7.6 db in pad R2, 3.5 db in the hybrid coil) from the amplifier gain (33 db).
    Table XII. Transmitting and receiving gains
    EQPT switch setting	Transmitting gain (db)	Receiving gain (db)
    2W	20	16
    4W TEL	17	27
    4W TLG	25	27
    b. Limitations on Use of Maximum Transmitting and Receiving Gains. Maximum transmitting and receiving gains cannot be utilized in both directions of transmission since the use of gain is limited to the permissible loop gain, 26 db in the case of a type H carrier terminal. For example, if a gain of 20 db is used in the transmitting direction (two-wire termination) only 6 db of the approximate maximum of 16 db is available for use in the receiv-
    gain in .the transmitting direction and 10-db gain in the receiving direction. Although the currents transmitted to or received from the line are in the carrier band, the graphs show frequencies in the voice band since the test transmission from jacks 2W HYB is made at voice frequencies.
    d. Impedance. (1) Two-wire operation. The nominal input impedance looking into the switchboard at 1,000 cycles is 600 ohms.
    (2) Four-wire operation. The nominal input impedance on the voice side looking into each of the four-wire branches is 600 ohms. On the high-frequency side looking into the directional filter the impedance is about 600 ohms, matching the impedance of the high-pass section of the line filter on the carrier line panel.
    87. Terminal Switches
    ing direction. When the permissible loop gain is exceeded the higher gain may upset the gain-loss balance and result in the circulation of singing currents in the terminal. When necessary, however, the loop gain may be exceeded by about 2 db since a 2-db increase over the 26-db loop gain generally will not upset the gain-loss balance sufficiently to cause singing.
    c. Gain-frequency Characteristics. Figures 81 and 82 show representative transmitting and re-
    Two switches are used for changing connections in the terminal panel: switch EQPT and switch LINE. Switch EQPT controls the circuit arrangements on the voice-frequency side of the terminal. In the WIRE positions switch LINE switches the band pass and directional filter units so that each selects the proper frequency for an East or West terminal. In the RADIO position switch LINE provides proper circuit arrangements when the two terminals are interconnected and used with a radio link.
    ceiving gain-frequency characteristics for terminal
    circuits with a two-wire termination, as measured
    a. Switch EQPT. This is a two-section, three-
    between jacks 2W HYB and DIR FILT LINE. Curves plotted show the gains at various frequencies
    position, rotary circuit-selector switch which is con-
    trolled by the EQPT knob on the front panel; the three positions are marked 2W, 4W TEL, and 4W
    relative to the gains at 1,000 cycles and are for a TLG. Although each section has 12 terminals on the terminal adjusted to a 26-db loop gain, with 16-db front and 12 on the rear, terminals bearing the same.
    -	0 -- -q  —-—--------।----nr---— -----------‘---------------i------------
    -	7 -- I-------------------------------------------------------------—----
    m	\	I
    o	,	\	/
    -	■* --L—\-------------------—----------------------------------—----/-----
    00	2000	2400	2800	3200
    FREQUENCY-CYCLES PER SECOND
    TL5I588
    Figure 81. Transmitting gain-frequency characteristic.
    101
    -9 --------------------------r—  —|----------------------------------------------
    • 6	--------------------------------------------------------------------1 .------
    H
    .7----------------------------------------------------------------------#--------
    ii
    _6-------------------------------------------------------------------------------
    S -5 -----u------------------------------------------------------------1L__________
    \ / ✓
    J	\	ft
    UJ	\	/ t
    |	----t----------------------------------------------1_	/£----------------
    w	\	WEST X	/ /
    «■ -2 ----—X---------------------------------------------\/'-----------------------
    , \	X/
    \	'	east----X	^zTz
    -I ----X— V— --------------------------------------------------------------------
    0--------- ------------------------------------------------------—-------------—
    ♦ I I—----------------------- ■ ------1—-----------------------------------------
    400	800	1200	1800	2000	2400	2800	3200	3800
    FREQUENCY-CYCLES PER SECOND	TLSISBO
    Figure 82. Receiving gain-frequency characteristic.
    number are metallically connected together and are not insulated from each other (that is, terminal 1, rear, is metallically connected to terminal 1, front, etc.). Rotor blades of various shapes make contact with these terminals and set up the desired connections.
    (1) 2W Position (fig. 83). In this position the terminal is arranged for a two-wire termination. Schematically, the circuit is as shown in figure 75. Note that hybrid coil HYB is connected to the switchboard side of the terminal, the balancing network, transmitting low-pass filter LP, and pad R2.
    LP
    --------------------------------X M T G ——
    „	low-	_ To
    PASS	M0D
    ----------- -------- FILTER ----
    ______ Z
    EQPT	EQPT
    SECTION I	SECTION 2
    —I—	r	1	if)2 ।
    I "o	O3 ,	Acio I Ho	p3 1
    to	n 4	QC3 •	H 4 1
    Io Q LW—I—	I	Y	|i0o q U*o-4—I
    ( *7	„__~___ L front') ^ 5 I	■ y C4 I front') . 1
    —o——IH 19° I r-	icii I 0	1 0 1
    I 8C o | 06 I	___otx-oJ I I a° o I
    to °°	!	7! I hyb iRI2 1	7|	;
    2-WlRE- DROP 2W HYB 1	I 1 —o-CJTl- —.-GnTVo-ool	,	I
    V-F EQUIP x c=) (=□	।	1	1	I 1 Cl C2 I j	I
    j> S	1	12 O1 1 2	]	4	I 12 o 1 2	1
    -R---------,-Lx IY1 --------------------------- w IW|
    k A8	4-.	J_______L	IA sa
    Figure 83. Switch EQPT in 2W_ position.
    102
    (2) 4W TEL Position (fig. 84). In this position the terminal is arranged for a four-wire termination. Schematically, the circuit is as shown in figure 77A. Note that pad Rl is connected into the transmitting path and that coil HYB is connected as a repeating coil. Three of the coil sections are connected in series to form one side of the repeating coil and the two sections connected to filter LP are unchanged. Note also that the output of the receiving amplifier is now connected directly to the four-wire line.
    (3) 4W TLG Position (fig. 85). In this position the terminal is also arranged for a four-wire termination. Schematically, the circuit is as shown in figure 77B. The arrangement is the same as that described for the 4W TEL position except that pad Rl has been removed from the transmitting path and that coil HYB is connected directly to four-wire line.
    b. Switch LINE. This is a three-section, four-position switch, similar in construction to switch EQPT. It is controlled by the LINE knob on the front panel and the four positions are marked WIRE EAST, WIRE WEST, RADIO TRANS, and RADIO REC. In addition to the three sections, there is a brass shield plate between each section and at the rear of the switch. These 3 shield plates are
    each equipped with 12 soldering terminals around their perimeters. The three plates are all connected to the ground and the soldering terminals provide convenient ground connections for the various equip ment units. The shield plates are not shown in the three figures showing the arrangements for the four switch positions.
    (1)	WIRE EAST Position (fig. 86). In this position the terminal is arranged for operation as an East terminal. Schematically, the circuit is as shown in figure 6. Filters BF and DF are so connected that their high-frequency sections are in the transmitting path and their low-frequency sections are in the receiving path.
    (2)	WIRE WEST Position (fig. 87). In this position the terminal is arranged for operation as a West terminal. Schematically, the circuit is as shown in figure 6 if the frequency values shown in parentheses for filters BF and DF are used. Filters BF and DF are now so connected that their low-frequency sections are in the transmitting path and their high-frequency sections are in the receiving path.
    (3)	RADIO TRANS and RADIO REC Positions (fig. 88). Two terminals are shown interconnected for radio link operation. Switch LINE of the
    TO 4-WIRE V-F EQUIP.
    . A9 .
    V------------------------------------------------------------- XMTG
    LOW-	_ T°
    4W TR MOD IN -----*	PASS	MOD
    __	_ ____________________________ FILTER _
    •> <-	PAD	>
    AK) MS	8 DB	------------
    ।-------------- LCJ F r_"_;±4
    4----£ 1 U------------------►WjJ	|	Q7 I
    1 "o	O3 1	HYB 1	I Ho	]
    I 10 n F-v4 !	cVIT-rrr-c	I	Li A I
    0	Fr°I—	I	110°	P"''-T”
    FRONT'' I) j	I-------- front ) 7 J
    I 9° T4---------	| 9° I 05
    I 8° o °6 I	|	8° o । °6
    7,1	7 l
    |	]	I EQPT	I	i	I	EQPT
    I SECTION	!	| SECTION 2
    I	I	I	I	1	I
    12 o	j	2	|	_J_J2	o	! o2
    MJ ! <■> i	fTPM i °31
    M3? M d	■	°4i
    I Mb	I
    I-------1----1	I--------------1
    1------------------ ----------------------------------- CARRIER -
    ______________________- LEAK
    ...	--------- SUPPRESSION
    .r, r.	______________________________________ J CIRCUIT
    R	__________L_j--------L_4 to
    RCVG ,R9y,G
    4W REC DEM OUT ------	----- amPLR ‘ ^SS
    m	—m ' N FILTER
    ___O>----------------------------------------------------- TL5I563
    Figure 84. Switch EQPT in 4W TEL position.
    103
    TO 4-WIRE
    V-F EQUIP.
    zA9
    -o--------------------------------- UP
    XMTG	| __
    4W TR MOO IN ---------*	-----------	L0*'	- °
    PASS	“00
    --------------------------- filter
    a io	r-H	________________
    I 12,1	}---------I 12 0 f~2 " I
    i° i HYB u° c\C±3 !
    il0o q jSxL-d prywo Lo q vT? ।
    I v"0"’	-------- 19.FRo"Ti<	----------------<■--	---1 TO
    RCVG	RCVG
    4W REC OEM OUT ■*-----	-------AMPLR ‘ LOW-
    ,	PASS
    < <,	— FILTER
    A12	J
    Figure 85. Switch EQPT in 4W TLG position.
    BF	TR.GAIN TR
    r MOD OUT . c	_
    TO J I	filter	££ amplr
    mod i f e ■*	~1	_Z~	—x
    I	? ]	, ..._7.4OO-IO.I5O~	, 1Klr_	LINE
    ---6 1—.	LINE	_______LINE	SECTION 3
    2	SECTION I	SECTION-2-------------------------------—
    |	.	।-------------1	---------------,
    I	।	I BIIO—------------]|	I ________
    wUhn nk/ytq	filL,
    .110 //front 4|	J 10 V/FRONT 4I	! |Q 	1 9 kx yJ	«
    190 Q I 05	I 9° Q I °5 [	05 '	4]—Hi q TO
    I	8°	।	°6 I	I	8°	I	°b ।	XJ 8°	1 | 06	I	/ , ,	,q„, HIGH PASS
    I	7 |	I	1	7 ।	1	I	71 1	1	__	FILTER ON
    I	1	I ।	------------1	°F A2 ’CARRIER
    r°  	1	I	I I	1	।	\	—-o- LINE
    I 1___________। ill	i!i ,\l
    i 1'1 I I • fTi----------------------n	1 I 1 I
    <1 I2O HI2	kJ I2O _________.J	I I2o 0 02 iJ DIRFIL 4,I5O-6,9OO~
    °b7 —L| J
    03°-----TioTfl °REAR ° I B60“-tqo-*U °REAR 0 I B9O—------10* K °REAR °4 I 4="
    ;9«X=, eq ।	•»!	-s |
    I 8°	0	°6	|	| 8o 0	°6	|	I 8° o, °b I
    1_______1_____j	I______,7_____j	L.______—-I ———
    ------BF	-- REC GAIN ---------------1
    DEM IN D	------- ------------------------
    31 kr>	BAND-	RCVG
    J	PASS	GAIN
    g ______________________ FILTER	CTRL
    f	n_fr
    4,150-fa,900~
    TL3I5M
    Figure 86. Switch EINE in WIRE EAST position.
    104
    BF	TR GAIN TR
    MOD OUT ---? ?..—~	BAND-	XMTG	XMTG
    PASS	GAIN AMPLR
    TO ? ji	FILTER	CTRL
    M0D Ro	~	~	LINE
    p j	LINE 7-400''0 150	LINE	------ SECTION 3
    ~£	SECTION ।	SECTION 2	“
    -	।---------।-----------------------t	|-------------1	•
    III	III	BHO—---1------il	|	----
    I >21 0 L______L_	I	121 ° L______I_	I '?o i°2 I	i
    i kZzz^W 1 'OzzCy '	! "o/?cZ!q i ——
    i !!> kUNT	OA I	!IOo	(|R °NT	04 1	ll0°	°4|	DIP FIL	7400-10,150^
    • A >	।	।	A >	'	। 9Z'ZZZ c i
    | 9o V	।	o5 I	|	90 V ,	05 I	I—05	L_^-r—'	TO
    I	1	, I	I	I	Ot I	Si	AO I I o6 ,	/	_A_	HIGH	PASS
    8° o I °t>	60 o ; 6	r I 4 I 1	'------ FILTER ON
    ’i	I I ’;	!	l7------J; ; 0F
    «s°- j___________________i ;	; J__________;	;	; I \l ...rd
    h 12o pi2	I	U	iz. }i;-2	III I	i2» °\°z	y c"°'lt
    HrU	A-J—-o bi	*-—067 —hwZ^^rr-i	i H
    830—----fioZ] CfREAR 04} B50-ZW'v CfREAR041 690--------hk*,' REARL^ °4 !
    o5l | 9o Z 05 ]	4-/Z3
    I 8° o °6 I	}	8° o °6 I	I 8° o °6
    ■	7	I	;	7____1	_ _i ----J
    --------------- BF	--- REC GAIN
    DEM IN D
    3?~L#p~------------------ BAND-	RCVG
    I	PASS	GAIN
    jo	FILTER	CTRL
    s	“	WP
    2 	4,1 50-6,900~
    TLSISB*
    Figure 87. Switch LINE in WIRE WEST position.
    upper terminal is in position RADIO TRANS and switch LINE of the lower terminal is in position RADIO REC. Schematically, the circuit is as shown in figure 8. Note that the transmitting paths of both terminals are connected to filter DF of terminal 1 and that the receiving paths are connected to filter DF of terminal 2. Note also that controls TR GAIN and REC GAIN and the sections of filter BF have been rearranged.
    88. Functioning of Type H Carrier Repeater (fig. 89)
    West-to-East transmission, using the 4,150- to 6,900-cycle side band, enters the repeater through the W LINE FILT and W DIR FILT LINE jacks and passes through the 4,150- to 6,900-cycle unit of directional filter W DF. From the filter the side-band frequencies pass through control W-E GAIN, to and through the W-E amplifying circuit, and through the 4,150- to 6,900-cycle unit of directional filter E DF. From filter E DF the side band passes through jacks E DIR FILT LINE and E LINE FILT to the high-pass unit of the carrier line filter and out to the East line. East-to-West transmission, using the 7,400- to 10,150-cycle side band, follows a similar path through the repeater, the transmitted side band being selected by the 7,400- to 10,150-cycle units of directional filters E DF and W DF and passing through control E-W GAIN and the E-W amplifying circuit to the West line.
    a. Directional Filters. The two filter units in each direction of transmission are arranged to provide maximum attenuation to circulating singing currents with minimum distortion to the desired transmitted side bands. The two filter units associated with each directional filter are inclosed in metal containers designated E DF and W DF respectively. The directional filter for the East side is the same as the directional filter used in the terminal panel; figure 80 shows simplified schematic diagrams and transmission characteristics for the E DF filter units. Figure 90 shows simplified schematic diagrams and transmission characteristics for units of the slightly different directional filter used on the West side of the repeater.
    b.	Gain Controls. Controls W-E GAIN and E-W GAIN are the same as the TR GAIN and REC GAIN controls described in paragraphs 79 and 80. The repeater gain controls are adjusted by knobs on the front panel designated W-E GAIN and E-W GAIN.
    c.	Amplifiers. E-W and W-E amplifier circuits are the same as the transmitting amplifier circuit used in the terminal. The circuit is described in paragraph 79e.
    d.	Power Supply (fig. 91). The circuit which supplies power to the tubes is the same as that used in the carrier terminal (par. 82), with the following exceptions:
    105
    CHANNEL I unn miT	R"F 1	TRGAIN TfL	CARRIER TERMINAL I
    r. °p yT	_______ ______________________ ______I ________ __________ LINE SWITCH ON
    T0~]J	-SR	feg
    mod —4 |	J—	—L	J— ---------—	—L
    ____£ |	7,400-IQI50~
    LINE I	’	| LINE	;	I	;-------;---------	I line
    SEC 1	l2| ° jU_____I___ SEC. 2 .	12I ■ °	12_’	I I2O	--->- ri SEC 3
    —°3 ’ r-Xx xyf °3 •	1"° Y y>^ti *_____________l—i
    Jl0° [J L] °4}	jl0° (j  r°
    8° o 1	6	*	|	8° o 1 °6	।	(|	8° I I °6	|	/ >-------O- HIGH-PASS
    TO __	I 7 |	|	7 ‘	।	—J___________J71 I DF	FILTER ON
    °sc :	:	!	।	!	।	j !	!	\	sier
    ________।	।	•	;_______[_	।	j	।	yj—O	panel
    kdl2o I1 Ip2-----1---	\| I2O I' I 2 I	j I2O 0 ]o2 JJ DIR FIL 4.(50-6.900-
    iX. .p/ ~3 1	l\	3 i	1  /-—Yi
    Tyv	rZLJy A^i~|	i I
    ITT?-*) O’	O 4a	| o—*4 cf 041	-J—o-d J O 04 I ±
    |\5 REAR	|	|i°\\>REAR	| 10 <\REAR A	.
    ri i 9° °s ।	i 9°	°5 ।	hrTv °5 |
    OH I 8° 0 °6 I	I 8° 0 °6	|	I e° o °6	|
    LJ I_________1______J	I____. __7______I REC |_______________I_____j___________
    DEM 1__	BF	GAIN
    IN
    BAND-	RCVG
    J	PASS	•	GAIN
    g	_ FILTER	CTRL
    I? 1	4.150-6.900-
    Wb	' B7 BS
    ■ Q bj	Adi	obs	---------p p	Abu
    CHANNEL 2
    OB3	OBI	CB5	876 6>B9	OBII
    	1	BF r-1-TR GAIN p* p* TR ^MOD OUT-------------------------------------------------J I	[—
    3	BAND-	XMTG	XMTG
    J	PASS	GAIN	AMPLR
    |	---*	^-FiLTER--^	CTRL----------,
    7,4 00 -10,150-
    line r 7“ ’““I line ;	;	■;	।	•	i—	♦ line
    SEC. I | 121 ° I2-------1—।	SEC. 2	| ISA ° 12	I I2O 4 02 J	J~I	SEC. 3
    J—. ’	।	31	1"°	। I
    •lO L/	4I	110	\p |	110 p7FR0NT\ \ 4.
    । o Q, II o ।	। o Q. I) 0 ।	I ° L	U o 1 OIR FIL 7.4 00-10.150'
    ’ Q FRONT) <7	।	I FRONT 7	I Q	VT •
    1 ° I °5	| 90	'^°5l	| X---------|-J TO
    •	80 J	06	,	.80	!	06 I	Fj	8° I j	°6 I	/ ______04-1 HIGH-PASS
    TO_	'	?!	7 I 1	I	I7!	• DF	FILTER ON
    OSC	I	I •	.	I I	I	I I	\	A2 CARRIER
    ll«	1	I	' I \	UNE
    _J________ I	I	I	I_______]	[	;	i	XI----L J PANEL
    Id	I2o J'jj_____J	k!	I2O I' Y	|	1	I2o °|o2	\) DIR FIL 4.150-6.900-
    xY-!-	r
    --j—p-*u O' □ o4 |	-1—o-Uj o' L I °41	-----|—o*n °	°4 I
    I 1°	REAR |	I 10	REAR .	j l°k/REA5v	I
    .9°	o5 ।	qo	o5 ।	LJ-tyTy \ > o5 ।
    el	1	I 9	|	I 9	I
    L_2_L7_°1_J	L_f__°7_l6_J RLC L-±_x_Ofe_J I__________________________
    DEM	BF	GAIN
    IN |	____________________
    3	BAND-	RCVG
    r	PASS	GAIN
    t	filter	'CTRL _ CARRIER TERMINAL2
    F	i i	Tr	LINE SWITCH ON
    '	RADIO-REC
    TL5I587
    Figure 88. Switches LINE in RADIO TRANS and RADIO REC positions.
    106
    W-E	1 W-F
    GAIN	W-E	Z-J-\JAN-3IOA W-E
    IN	|—f—~~ Y	OUT
    ------------  —in—n 5O0B	Jjfc <	'Ll	XXfo
    —*	+Ne I U I if	—*
    steps	|	C3 04 Rl I ।
    u,	----- ------------i M X II U II. i \am-4 a-------------
    ?	----- f*	10,000 IMF 5 000-0.1	3
    H -1	-	MMF __fa_____p	q
    c	w df	E DF C u-
    w2 |--4----t-i	650A	r—1~—-—-r—>	£ -
    z ce ।	I	----- | dir fil	— —
    L °	4,?50 6,900^ I	Hl ------ --------b	I 4,150-6,900^ I °
    X I	?~r~s°AR	XvrH
    TO	Bl	---------CIRCUIT—J	FA	TO
    WEST	><	I	0 0------ /	| ZZ	EflST
    CARRIER-	=_	|	I	_____ ।	|	“ Cfl,R,?,'cEB
    LINE	>< I	8 A	I	1	? <	Xl?ER
    FILTER 2 A I	X	|	| pg 6 F'LTER
    I—f. |	’	I T I I >
    DIR FIL 1	I DIR Fil
    SHIELD 3	7,400-10,150^ |	r.AOO-'oT'SD^v	7 TO
    ON -----O	I L—I--------- |	I _____________|	O  ON
    CONNECTING I	--------------1	r————------------—1	[ CONNECTING
    WIRES ~	__ E-W	c	- WIRES
    UJ-JAN -	E/W
    E-W	Z^Z\3IOA	e-w	gain
    OUT	f ZZZ Y IN
    L .	r L J pot
    -—	ill TT । ii 5.°nob	-—
    r [ 1	he hi	tri	206
    R3 C6 C5 \l	steps
    ---------------!> 4—wv——if—•——if—	s>  ---- ---------------—1 5,000 IMF 10,000----------------------------------------------------S' -
    »	I R4	MMF
    LE----m-------
    NOTe+ is SYMBOL FOR FIXED CAPACITOR	650n	n l,ll<
    Figure 89.	Type H carrier repeater circuit, simplified schematic diagram.
    \ A A (XT “’X-t' / :-===+zzzzzzVzz"g2EEr"7-=== 26 _— ------X-----------------—         -/-----------------
    24 -----------\---------------------—-----------f---------
    “	\	z □
    20 -----------1-------------------------------y-------—---
    CD	\	/
    Q	\	/♦
    . 18------------J-----------------------------4------------
    «n	I	/
    I	/
    O i6------------X---------------------------4--------------
    14------------1----------------------    J---------------
    \	RECEIVING	TRANSMITTING	/
    i2-------------1-------    4— — — — — — — —
    10-------------1--—-----------------------~4-------------
    8------------------------------1----------.--------------
    6------------------------------I-------4-----------------
    2-----—----—-------------—--------------------------------—
    . I	2	3	4	5	6	7	8	9	10	II	«2	13	14
    NOTE ZjF IS SYMSOl f0R FIXED CAPAC»9Q
    Figure 90.	Transmission characteristics of directional filter IP DF.
    107
    (1)	Resistor R6 is connected in series with the winding of the secondary which supplies power to the heaters of the tubes. In the terminal the heaters of three tubes are supplied by this winding of the secondary, whereas in the repeater only two heaters are connected to this winding. Resistor R6 is included in the heater power circuit to compensate for the reduced load.
    (2)	The resistor coded Rll in the terminal is coded R5 in the repeater; capacitors coded C9 and C8 for the terminal are coded Cl and C2, respectively, for the repeater.
    89.	Repeater Transmission Performance
    a.	Gains. (1) Maximum gain. The repeater will provide a maximum gain of approximately 29 db in either direction of transmission for carrier sideband frequencies equivalent to the 1,000-cycle point in the voice-frequency band. This 29-db gain results from an amplifier gain of approximately 32 db less about 3-db loss across the directional filters.
    (2)	Usable gain. The loop gain for a repeater is limited to 45 db and thus the maximum repeater gain
    of approximately 29 db cannot be utilized in both directions of transmission at the same time. The sum of the gains in the two directions must be held to 45 db to meet singing margin requirements.
    (3)	Gain-frequency characteristics. Figure 92 shows representative gain-frequency characteristics for both directions of transmission. These gains are for a repeater adjusted to a loop gain of 30 db, with 15-db gain in each direction of transmission. As the loop gain is increased the transmission-frequency characteristics may be expected to become somewhat less uniform.
    b.	Impedances. The carrier-frequency impedances looking into the repeater from either direction are approximately 600 ohms, matching the high-pass unit of the carrier line filter.
    90.	Functioning of Type H Carrier Line Panel Equipment
    The low- and high-pass filters and voice-frequency repeater and phantom balancing equipment required for use with the carrier terminal and repeater panels are contained on the carrier line panel. One carrier
    PWR 9	5
    H,---r-------------------------------------------------—r—
    10fVAC	v. .oli
    H2---‘   ---------------------------------------s/VW-o  o	>
    0.5 0.	§
    6 M D	T\-----------°---1 §	TO
    P	> PI	L °	105-125 V
    r ,	.7 V.	a s	■ 50-60~
    P ---1---------1-----------HP J-H-------7	9	| |	SUPPLY
    I	D	° g__2
    I50VDC R5 > Cl ~C2 —*-	P2\y	7 g i °
    I MEG ? 4MF 'T	4MF ZT	-----------►<>-g g
    o —LjJ---------1---------------------------- --------------------------.
    .	TL5I577
    -L is SYMBOL FOR FIXED CAPACITOR
    T
    Figure 91. Repeater power supply circuit.
    16 ------—,------------------------
    -----y'—z
    12---7---——-----X—f--------——--\---
    /	WEST TO EAST	’	'	EAST TO WEST
    10---/----------------I-1__________
    tn	’	1
    Q
    Z 8---------------------------------
    <
    0
    6----------------------------------
    2----------------------------------
    ol---------------------------------
    3000	4000	5000	6000	7000	8000	9000	10000	11000
    FREQUENCY-CYCLES	.51591
    Figure 92. Repeater gain-frequency characteristics.
    108
    line panel is required with a terminal panel and two with a repeater panel. Two panels are required to form a carrier transfer or bypass set.
    a. Carrier Line Filter. The carrier line filter consists of three units: a low-pass filter, a high-pass filter, and a line filter network. Each of these units is inclosed in a separate metal container and all three are assembled on a common base.
    (1) Low- and high-pass filters (fig. 93). The
    low- and high-pass filter units, which together form the line filter and are designated LF, provide frequency separation between the voice-frequency circuit and the carrier-frequency circuit operating over the same pair. The high-pass filter unit is balanced on the line side but unbalanced on the drop side. The low-pass filter unit is balanced in both directions. As viewed from the line side, the low- and high-pass filter units in parallel have a nominal impedance of
    FT
    B3O----1—O-»---9		i i
    DROP	P	P	3 -X-	।	LINE
    SIDE	.	}	?	f fc
    A 4 O f—o----1---------1-----rMto----------o—i---------O A 2
    . e ~	3	HIGH-PASS FILTER UNIT	I I
    “tor5—[toTi m m I—to-1
    pass ।	IwJ	J_ LsbxJ §	IwJ _L ImJ
    s*d°ep I	M	T pi I	pi T pi
    A6 O I	O	>-|(—X1	1 —° o4 T	o o—। —6 o	O—j	■ ■—
    I 4	LOW-PASS FILTER UNIT	2 I
    I_______________________________________I
    LINE FILTER LF
    3 6 -------------------------------------------1------------------------------[“*----- ------------------
    V 34----------------------------------------------------------------------------------------------------
    32--------------------------------------------------------------:-------------------------------------
    30----------------------------------------------------------------------------------------------------
    28-------------------------------------------------------------------—--------------------------------
    26----------------------------------------------------------------------------------------------------
    24----------------------------------------------------------------------------------------------------
    22 ---------------------------------------------------------------------------------------------------
    20----------------------------------------------------------------------------------------------------
    ItD
    O
    I 8----------------------------------I----------------------------------------------------------------
    <0	I
    O	I
    -*	16----------------------------------L---------------------------------------------------------------
    <4----------------------------------------------------------------------------------------------------
    ' I ‘	2	3	4	5	6	8	9	10
    FREQUENCY-KILOCYCLES PER SECOND
    Tl-51203
    NOTE IS SYMBOL FOR FIXED CAPACITOR
    Figure 93. Transmission characteristics of line filter LF.
    109
    690 ohms at voice frequencies and 600 ohms at type H carrier frequencies. The nominal impedance looking into the drop side of the low-pass filter unit is about 690 ohms and looking into the drop side of the high-pass filter unit about 600 ohms. In the following subparagraphs the balance between the nominal impedance and the actual impedance for a specific frequency range is expressed as a loss across a hybrid coil.
    (a)	With the high-pass drop side terminated in 600 ohms and the low-pass drop side terminated in 690 ohms, the balance between the nominal impedance of 690 ohms and the actual impedance looking into the line side of the line filter at frequencies between 300 and 2,500 cycles should be not less than 10 db.
    (b)	With the line side terminated in 690 ohms and the high-pass drop side terminated in 600 ohms, the balance between the nominal impedance of 690 ohms
    and the actual impedance looking into the low-pass drop terminals of the low-pass unit of the filter at frequencies between 300 and 2,500 cycles should be not less than 18 db.
    (c)	Looking toward the terminal from the openwire line the impedance at carrier frequencies is about 600 ohms when control REC GAIN is set for 0-db loss. This impedance is fairly uniform over the two transmission bands.
    (2) Line filter network. Line filter network LFN balances the low- and high-pass filter units and is connected in the balancing network circuit of a voice-frequency repeater when the repeater is used on an open-wire pair with a type H carrier system. With the LFN network, which is connected on the network side of the repeater hybrid, terminated in 690 ohms on the drop side, and the line filter terminated in 690 ohms on the line side (fig. 94), the balance between the line filter and the line filter net-
    L F
    TO TESTING EQUIPMENT_____________________i---------L-______,
    HIGH-PASS	I	HIGH-	/	X
    I	PASS	> 690XL
    DROP SIDE_____SECTION
    J________L ।------------------------------11
    __________	_____________ V-F TP _______________________। low- U
    7	REPTR	LOW-PASS	I PASS
    690	£ LFN	Hco?lD	drops.de |SECTI0N I
    -------4----L J----------	—------------------__________p
    TO TESTING EQUIPMENT	TL-51284
    Figure 94. Measurement of balance between LF and LFN.
    —
    35 EEEEEEEEEEE=EEEEEEEEEEEEEEE==EE===::==
    30 EEEEEEEEEzEEEEEEEEEEEEEEz-EE-EEEEEEEEEEE
    25 ==:zzzzzzzzzzzzzzzzzzzzzzzzzzzzz5s;-zzzzz --------ZZZZZZZZZZZZZZZZZZZZZZZZZZZZ-ZZZZZ
    O _______________ZZZZZZZZZZZZZZZZZZZZZZZZZZ-'
    I 20 zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzEEEEEEEE
    V) --------------------------------------
    CO ZZZZZZZZZZZ---------------------------
    o । 5 zzzzzzzzz-zzzzEEEE’EEEEEEEEE’EEE’--'---
    io EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
    3 EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
    zzzzzzzzzEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
    O	500	1500	2500	3 500
    FREQUENCY-CYCLES PER SECOND
    TL 51265
    Figure 95. Loss-frequency curve showing balance between LF and LFN when connected to hybrid coil.
    work, expressed in terms of loss across the hybrid, should be as follows:
    (a)	At frequencies between 500 and 1,700 cycles the loss across the hybrid should be at least 32 db.
    (b)	At 300 cycles the loss should be at least 29 db.
    (c)	At 3,000 cycles the loss should be at least 24 db.
    (d)	Figure 95 is a graph showing the loss across the hybrid coil in figure 94 as a function of frequency.
    (3)	Frequency characteristics. The carrier line filter and the line filter network are shown schematically in figure 93, which also shows representative loss-frequency characteristics of the low- and high-pass filter units. The low-pass unit passes voice frequencies up to about 3.000 cycles and suppresses the carrier frequencies. The high-pass unit passes frequencies above about 3,800 cycles and suppresses voice frequencies. There will be some attenuation variation between line filter units, but the variation
    110
    usually will be at the frequencies adjacent to the cutoff frequencies rather than in the bands passed. Slight changes in attenuation also may appear with temperature changes.
    (4)	Losses. The low-pass filter unit introduces a slight loss into the voice-frequency circuit, generally about 0.2 db at 1,000 cycles. The loss to the phantom circuit from the low-pass filter unit will be about 0.15 db.
    (5)	Lightning protection. The line filter is designed to withstand momentary peak voltages of 1,000 volts. However, to provide additional protection against lightning surges both to the line filter and to the directional filters contained on the terminal and repeater panels, a varistor is connected across the drop side of the high-pass filter unit. This varistor consists of a thyrite disk so proportioned as to present a high shunt resistance to tolerable voltages and a low shunt resistance to excessive voltages. It is assembled on a small metal bracket which is mounted on one of the filter mounting studs. This unit does not take the place of the conventional office protector, » but merely adds to the lightning protection.
    b. Balancing Equipment Used for Phantom Operation. The line panel contains three balancing units for use in phantom operation: a line filter balance unit designated LFB, a line filter balancing network designated LF BN, and a line filter balancing network designated PH LF BN for use on the phantom circuit. An application of these units to a phantom circuit is shown in figure 14.
    (1)	Line filter balancing unit LFB. (a) Description. The insertion of a line filter in one side circuit of a phantom group requires that similar impedance be added to the other side circuit of the group to keep the phantom telephone circuit balanced. Line filter balancing unit LFB is used for this purpose.
    The balance between low- and high-pass filter units and the line filter balancing unit is such that existing noise on the phantom circuit will not be increased appreciably by the insertion of these units on opposite sides of a phantom group. The line filter balancing unit consists of a retardation coil and two resistors, and the unit is housed in a metal container mounted separately on the panel.
    Note. If both side circuits of a phantom group were equipped with type H carrier line filters the line filter balancing unit would not be used. However, the LFB unit must be used if different types of carrier systems are used on the two side circuits of a phantom group.
    (b) Losses. At 1,000 cycles the line filter balancing unit introduces a loss of about 0.2 db into the voice-frequency circuit and a loss of about 0.15 db into the phantom circuit.
    (2)	Line filter balancing network LF BN. When a voice-frequency repeater is used on a physical circuit equipped with line filter balancing unit LFB, a resistor, designated LF BN, is required in the network of the repeater to balance line filter balancing unit LFB. The balance between LFB and LF BN is at least as good as that provided between the low-and high-pass filters and their balancing network LFN. Resistor LF BN is mounted separately on the carrier line panel.
    (3)	Phantom line filter balancing network PH LF BN. The resistor designated PH LF BN is connected in the network of the voice-frequency repeater on the phantom circuit to balance line filter LF and line filter balancing unit LFB in the side circuits of the phantom group. The balance between PH LF BN and the LF and LFB units which it balances is at least as good as that provided between the low-and high-pass filters and their balancing network LFN. Resistor PH LF BN is mounted separately on the carrier line panel.
    Section XV. TROUBLE LOCATION
    91.	Technique of Trouble Location
    a.	Scope. This section of the manual covers trouble localization on an H carrier system terminated on a two- or four-wire basis, operated over either wire or radio link. For wire operation, an H system consisting of two terminals and a repeater is assumed. If the H carrier system is used in tandem with other carrier or voice-frequency systems, reference should be made to TM 11-2022 for procedures to localize the trouble in a particular system.
    b.	Organization. Table XIII lists the trouble tests which are covered in this manual.
    (1)	Preliminary procedures. These procedures outline the course of action on the receipt of a trouble report. All available data are first assembled and an analysis is made. The extension circuits are next checked. This procedure is designed to localize the trouble either in the H carrier system or in some external circuit.
    (2)	Systems trotible tests. These tests cover a ched of the extensions of the H carrier system, fol
    lowed by a check of the system line-up or of the system condition, depending upon the type of trouble reported.
    (3)	Panel trouble tests. These tests cover trouble localization procedures on the terminal, repeater, and line panel. A quick method is given for checking the gain in each direction of transmission, followed by a suggested procedure for isolating the trouble in a particular circuit or part.
    (4)	Apparatus trouble tests. These tests cover trouble location procedures on the individual parts of the type H carrier panels. Detailed testing procedures are given wherever possible, and suggested procedures are included where detailed tests are not practicable.
    Table XIII. Trouble tests
    	Wire	Radio
    	Paragraphs	Paragraphs
    1. Preliminary.
    a. General procedure		94a	94a
    b. Two-wire extensions and termina-
    tions			946	94Z>
    c. Four-wire extensions and termina-
    tions		94c	94c
    2. System.
    a Failure			95	96
    b Poor transmission		97a	97Z>
    c. Singing tests		98	98a
    3. Panels.
    a Terminal 		99	100
    b Repeater 		101	—
    c Line			102	102

    4. Components.
    a Power supplv		103	103
    b Amplifier			104	104
    c Oscillator			105	105
    d Filters 		106	106
    e. Potentiometers, switches, and jacks. .	107	107
    c.	Trouble Reports. Trouble on the H carrier system will be reported by either using or operating personnel during normal system operation, or by maintenance personnel in the performance of initial or periodic tests.
    (1)	Troubles reported by using or operating personnel. Trouble reports from this source sometimes may be vague or incomplete. While receiving the report the repairman should secure sufficient information to indicate a trouble such as one of the following:
    Failure to ring distant end.
    Failure to hear distant end after receiving ring.
    Inability to talk to distant end although distant end can be heard.
    Line is distant, although talking is possible. Line is noisy.
    Excessive crosstalk on circuit. Quality of transmission is poor. Circuit is singing.
    Upon receipt of a trouble report, the repairman will verify the report by talking, listening, and ringing on the circuit. Note any further symptoms which will indicate trouble in a particular piece of equipment, such as the ringer, etc.
    (2)	Troubles detected by performance of periodic tests. In many cases performance of periodic tests and adjustments will correct minor troubles on the H carrier system such as an incorrect circuit net loss, poor synchronization, etc. If trouble is indicated by any test, the corrective procedures given in this section will be followed.
    d.	Trouble Analysis. Analysis of the trouble report and all other symptoms which may be noted will indicateThe trouble as one of three types: system failures or abnormal speech levels; noise and crosstalk, which includes power hum, static, unintelligible interference, etc., and poor speech quality or singing, which also includes echo, hollowness and distortion.
    e.	Trouble Location. Wherever possible, detailed tests are given to aid in trouble location. However, in some cases detailed tests would be too involved to be of any value and in these cases general tests have been prescribed. The skill of the repairman will be a controlling factor in the length of time necessary to locate and clear a trouble. If the repairman is not familiar with methods of testing the equipment, trouble may have to be cleared by substituting parts known to be good. This procedure requires much time and numerous replacement parts must be available. The repairman who is familiar with the equipment may develop short-cut methods involving tone tracing and continuity testing which will immediately isolate the trouble in one piece of apparatus.
    92.	Test Equipment
    A variety of testing equipment is necessary for the installation, operation, maintenance, and repair of the carrier panels. This equipment is usually available at a voice-frequency telephone repeater or C carrier installation. All of the testing equipment required for trouble location work is listed in table XIV. Equipments equivalent to those listed may be used.
    112
    Table XIV. Test equipment
    Nomenclature	Signal Corps stock No.	Mfr’s No.	Description	Usage
    Audio Oscillator TS-379/U.	3F3570-1	WECo 19C (SPL).	Oscillator.	Supply testing power.
    Multimeter TS-380/U.	3F7127	WECo D-166852.	Volt-ohm-milliammeter.	Electrical measurements.
    Decibel Meter TS-399/U.	3F4270-2	WECo 13A (SPL).	Transmission measuring set	Measure test power.
    Tube Tester 1-171.	3F5681	Hickok Model 560 (SPL).	Tube tester.	Test vacuum tubes.
    Attenuator TS-402/U.	3F1775	WECo 5A (SPL).	Attenuator.	Insert loss.
    Test Set TS-190/U.	3F4316.1	WECo 67B (SPL).	Test receiver.	Continuity tests.
    			Magneto telephone or handset.	Listening and talking.
    •	4C7317D.1	WECo 217D.	600-ohm terminating plug.	Terminating.
    			Patching cords.	Making interconnections.
    93. Use of Diagrams and Charts
    a.	Drawings. The drawings furnished with the H carrier panels are helpful in shooting trouble, in tracing wiring, and in rewiring apparatus which has been replaced. Two copies of each schematic and wiring diagram listed below are furnished with the equipment and are reproduced in the rear of this
    Table XV. Drawings furnished with equipment
    Equipment	Schematic	Wiring
    Carrier terminal panel	B-400044-1	B-400044-2
    Carrier repeater panel	B-400045-1	B-400045-2
    Carrier line panel	B-400046-1	B-400046-2
    manual. If this equipment is installed in an apparatus cabinet, reference may be made to the power service circuit schematic and wiring diagrams furnished with the cabinet.
    b.	Schematic Diagrams. (1) Schematic diagrams generally may be classified as circuit schematics and application schematics. Use the circuit schematics generally when locating trouble in the equipment, as they show each circuit completely and include the designations and pertinent characteristics of each piece of apparatus. An application schematic drawing shows the arrangement of the circuits which form a complete unit. Assignments of terminal
    strip terminals on panels, together with the external wiring connections, are shown.
    (2)	All of the type H carrier drawings are in the B letter series. These drawings have six digit serial numbers. The schematic drawings are identified by -1 after the serial number. When more than one sheet is required to show a circuit, this is indicated on each sheet as 2 sheets, sheet 1 ; or 2 sheets, sheet 2.
    c.	Wiring Drawings. (1) Wiring drawings are generally associated with schematic drawings. They show, in a semipictorial manner, the wiring arrangements as viewed from the wiring side (rear) of the panel. The wiring symbols used are explained in notes on the drawing. The size of wire, color codes, cabling, and the connections between the terminals of each piece of apparatus forming a circuit are shown. Use wiring drawings primarily for trouble location work when it is necessary to check the wiring. For the type H equipment the wiring drawings are also assigned in the B letter series. Each drawing bears a serial number corresponding to the associated schematic drawing. The first sheet of a wiring drawing is suffixed -2, the second -3, etc.
    (2)	Wiring drawings covering the H equipment use the so-called “airline” system of showing connections. In the airline system, each individual piece of apparatus, or each group in some cases, is
    113
    numbered, and the lines representing the individual wires from each piece of apparatus are carried a short distance and terminated in a base line. These individual lines between the apparatus and base line are called feed lines. Each feed line is numbered to correspond with the identification number of the piece of apparatus at which the other end terminates. It is not necessary to follow a connection through the base line and no provision is made for doing so. By observing the color and identification number included with the feed line it is possible to trace directly between pieces of apparatus.
    94.	Preliminary Procedures
    After a circuit utilizing an H carrier system has been reported in trouble, immediate performance of the preliminary procedures in this paragraph will serve two purposes: localization of trouble will be speeded by analysis of symptoms and conditions; the extensions will either be eliminated or indicated as the source of trouble. If the extensions are found to be free of trouble, turn to the proper paragraph following for directions on localizing the trouble within the H system.
    a.	General Steps. (1) Gather all possible information from the person reporting the trouble and also from circuit records, trouble records, etc. Data on how the trouble appeared, whether or not it appears intermittently, its presence in one or both directions of transmission, the condition of power and associated equipment, condition of other circuits on the same line, weather conditions, recent performance of the circuit, maintenance checks or repairs on the circuit, and other data, will all be of use to the repairman charged with locating and clearing the trouble.
    (2)	If the voice-frequency circuit on the same line has not been reported in trouble, check its performance by ringing, talking, and listening on it. The appearance of a trouble similar to that reported on the carrier circuit will locate the trouble in a line section or in some piece of equipment common to both circuits. Notify the operators or other using personnel to take the voice-frequency circuit out of service, and clear its trouble first. This may also clear the trouble on the H carrier system. It is advisable at this time to check other circuits on the same line or radio link system. External troubles, such as induction from a power line, or atmospheric disturbances, will eliminate the H carrier system as the primary source of trouble. If no trouble is found on any of the other systems, trouble probably exists in the H carrier system or its extensions and terminations.
    (3)	Analyze the assembled information concerning the trouble symptoms. If they indicate a trouble peculiar to one part of the system, many of the recommended tests may be eliminated. This analysis, if done properly, will save much time and labor. If the analysis shows that a line section, or equipment common to both the H and voice-frequency circuits, or equipment common to one direction of transmission, is in trouble, proceed to the proper paragraph following for localization tests. If the extensions of the H system are not eliminated by analysis, check their condition first.
    Note. Check of the extensions, either two-wire or four-wire, should be made at both ends of the system at the same time.
    b.	Check of Two-wire Extensions and Terminations. (1) Insert 600-ohm plug in jacks 2W HYB. (This will isolate the extension from the rest of the system.)
    (2)	Establish contact with the switchboard or telephone at the end of the extension by connecting a magneto telephone to jacks DROP at the terminal.
    (3)	Check the extension for ringing from the switchboard, talk with the switchboard, and listen for the presence of noise and crosstalk.
    (4)	If no trouble is encountered proceed with the localization tests.
    (5)	If trouble is found in the extension, notify other installations and clear the trouble.
    (6)	When the trouble has been cleared, turn to paragraph 111 for instructions on returning the system to service.
    c.	Check of Four-wire Extensions. The check of a four-wire extension, used either for telephone or telegraph, can be made in several ways. Follow the general suggestions given below.
    (1)	Check one pair at a time, by first blocking off equipment connected at both ends of the extension. Insert 600-ohm plugs in the jacks of the equipments both ways from the extension under test.
    (2)	Test the pair by talking or by making transmission measurements between the output jacks of the connected equipments. Listen on the pair for noise or crosstalk.
    (3)	Repeat the tests on themther pair.
    (4)	If no trouble is encountered proceed with the localization tests.
    (5)	If trouble is localized in extension, notify other installations. Clear the trouble in any practicable manner.
    (6)	When the trouble has been cleared, turn to paragraph 111 for instructions on returning the system to service.
    114
    95.	Procedure for Localization of System Failure, Wire Operation
    This test covers the localization of trouble in a type H system, where no communication is possible in one or both directions between the two H terminals of the circuit, or where the voice levels are excessively high or low. The test is actually a check of system line-up, and the following test equipment is required at each terminal and repeater installation:
    1 Audio Oscillator TS-379/U (not required at repeater).
    1 Attenuator TS-402/U.
    1 Decibel Meter TS-399/U.
    The test will be performed after the extensions at each end of the system have been checked and found to be free of trouble. It will consist of checking input and output levels at each installation. Minor deviations from specified levels will be tolerated at intermediate points, as long as total deviation at the distant terminal is not greater than 4 db. Sharp deviations from specified levels will indicate trouble. Information on proper levels should be shown on the circuit record cards.
    Note. All testing will be done under the direct supervision of the control terminal. If trouble is suspected in the receiving direction, viewing the system from the control terminal, make the test in this direction first.
    a.	Control Terminal Tests (fig. 96).	(1)
    Patch the test oscillator to the 2W HYB or to MOD IN jacks depending upon the position of switch EQPT. Adjust the oscillator for 1,000 cycles at the output listed below :
    Setting of switch EQPT	Patch to jacks	Output of oscillator
    2W	2W HYB	0 dbm
    4W TEL	MOD IN	+4 dbm
    2W HYB •	DIR
    OR	FILI
    MOD IN **	LINE
    (2)	Connect the OUT terminals of the attenuator to the input of the transmission measuring set. Set the attenuator for a loss equal to the level of the terminal output. (If specified output is +16, set attenuator to 16 db.) Patch the input of the attenuator to jacks DIR FILT LINE.
    Requirement: Measuring set indicates 0 dbm.
    (3)	If the requirement is met, remove patch to jacks DIR FILT LINE, and instruct the repeater to proceed with the tests outlined in b above.
    (4)	If the requirement is not met, notify other installations that trouble has been localized, then proceed with terminal tests.
    b.	Repeater Tests (fig. 97). (1) Connect the output of the attenuator to the input of the transmission meauring set. Set the attenuator for a loss equal to the output level of the repeater in the direction of testing. When notified by the control terminal, patch the input of the attenuator to jacks DIR FILT LINE on the side away from the terminal sending the testing power.
    Requirement: Measuring set indicates 0 dbm.
    (2)	If requirement is met, remove patch from jacks DIR FILT LINE and notify control terminal that no trouble has been found at repeater.
    (3)	If requirement is not met, remove the patch from the jacks DIR FILT LINE and patch the transmission measuring set directly to jacks LINE FILT on the side of the repeater toward the terminal sending the testing power.
    (4)	If an abnormally low power level is measured, trouble exists in connected equipment at the repeater or terminal installation (protectors, composite set, carrier line panel, etc.) or in the preceding line section. Remove the patch to jacks LINE FILT and notify the control terminal that trouble exists between the repeater panel and the terminal sending testing power.
    	IN	OUT	______;____________
    o sx.	—r,	TRANSMISSION
    OSCILLATOR 0	CARRIER	L J	v-~ ATTENUATOR ~H	° MEASURING
    (/ \	TERMINAL	~	° SET
    1.000 CYCLES *	\	/
    ---------------A		/_' \ ________________________________________________________________________________________INPUT CONNECTIONS'___/_INDICATION
    TcER.Mt\OPT PATCH OSCILLATOR	set for loss equal to TERMINAL	o DBM
    SWITCH ON TO OUTPUT LEVEL	--------------
    -----------------------——————	OUTPUT LEVEL. THIS LOSS WILL USUALLY 2* 2W HYB 0 DBM ---------------------------------------------------- BE 16 DB. MW TEL I MOD IN +U DBM------------------------------	1___________________________
    MEASUREMENT OF TERMINAL OUTPUT
    TL 51275
    Figure 96. System failure, control terminal test.
    115
    W(E) ♦ DIR FILT LINE	IN	OUT
    5LNE	„	—	transmission
    CONTROL	CARRIER *	v— ATTENUAT0R ZZ^ aZZyh) 8 MEASURING
    TERMINAL ------EC~7L_ REPEATER	(Q	 (j)	SET
    SET FOR LOSS EQUAL TO	INDICATION
    REPEATER OUTPUT LEVEL.	0 DBM
    THIS LOSS WILL USUALLY -----------------
    BE I6DB.
    MEASUREMENT OF REPEATER OUTPUT
    E(W)* LINE FILT	--------------- NOTES
    L,NE	TRANSMISSION	* JACKS ON SIDE OF REPEATER TOWARD TERMINAL
    T°	'v	O MEASURING	SENDING TESTING POWER.
    CONTROL	v	M *	SET	t JACKS 0N S|DE 0F REPEATER AWAY FROM
    TERMINAL	TERMINAL SENDING TESTING POWER.
    INDICATION
    NORMAL INPUT LEVEL
    MEASUREMENT OF INPUT TO REPEATER	n sis«a
    Figure 97. System failure, repeater tests.
    (5) If a normal power level is measured, trouble	etc.) or in the preceding line section. Remove the
    exists in the H carrier repeater panel. Remove the	patch to jacks LINE FILI and notify the control
    patch to jacks LINE FILT and notify the control	terminal that trouble exists between the previous
    terminal that trouble exists in the repeater. Pro-	repeater panel and the receiving terminal panel.
    ceed with repeater tests.	(5) If a normal power level is measured, trouble
    c. Distant Terminal Tests (fig. 98).	(1)	exists in the receiving terminal panel. Remove the
    When notified by the control terminal, patch the	patch to jacks LINE FILT, and notify the control
    transmission measuring set to jacks 2W HYB or	terminal that trouble exists in the receiving terminal
    DEM OUT, depending upon the setting of switch	panel. Proceed with terminal tests.
    EQPT. The output level should be as follows:	2W HYB.
    OR
    —_____________	OEM OUT*
    Indication of	11
    Patch to	transmission	transmission
    switch EQPT___________Jacks______ measuring set	LINE	cARR|ER ---,	° MEASURING
    2W	2W HYB	Specified ckt net	repeater—£XXi_ terminal	Q	set
    4W TEL	DEM OUT loss +4 dbm	_______________________________
    ---------------------—------------------------------------------------------------ OUTPUT COHHECTIOHS*
    TERM. EQPT PATCH
    /OX T <•	•	, •	.	,1	, 1 J	SWITCH OH TO INDICATION
    (2) If requirement is met, remove the patch and	—------2>HYB SPECIFIEB CKr
    notify the control terminal that the test has been	_______________MET ——
    .	....	HW TEL OEM OUT 08M
    completed. The above tests are then made in the
    ..	.	MEASUREMENT OF TERMINAL OUTPUT
    opposite direction.
    (3) If requirement is not met, remove the patch	line	-----------
    from the terminal, and patch the transmission meas- line _______________ ,	transmission
    1	to -----* MUy o MEASURING
    uring set to jacks LINE FILT.	repeater v /y 1 2 3 4 set _____________________
    . L T .	1	,,	,	.	, .	,	INDICATION
    (4) It an abnormally low power level is measured,	X ----------[normal input level
    trouble exists in connected equipment at the re-	measurement of input to distant terminal
    ceiving terminal or at the previous repeater installa-
    tion (protectors, composite set, carrier line panel,	Figure 98. System failure, distant terminal tests.
    116
    d. Test of System in Opposite Direction of Transmission. (1) If the preceding tests are completed and the trouble is not located, the opposite direction of transmission must be tested in the same manner. In this case the distant terminal takes over the functions of the control terminal and sends testing power to the line.
    (2) If this test is completed and trouble is not located, the trouble may be intermittent or may have cleared itself. Check the circuit again by listening, ringing, and talking, and if performance is satisfactory, return the circuit to service. However, keep a close check on the circuit for a few days to detect recurrence of the same trouble.
    96. Procedure for Localization of System Failure, Radio Link Operation
    If communication should fail on a circuit operating over a radio link section, failure of the two other circuits would indicate trouble in the radio link equipment or power supply. Before making any other tests on the H carrier system be certain that the radio apparatus is operating satisfactorily in both directions. If trouble appears to be in the H carrier equipment, a localization test similar to that described in the previous paragraph should be performed. Proper testing levels for radio link operation should be substituted for those listed. These levels will be found on the circuit record cards. If the trouble is localized in either terminal, turn to paragraph 100 for directions on locating and clearing the trouble. Line troubles, if found, should be cleared according to directions in the applicable technical manual.
    97. Procedure for Localization of Transmission Troubles
    This paragraph covers the localization of noise, crosstalk, poor quality, singing, and other troubles on the H carrier system. Localization will be attempted first by successively terminating line sections and installations as described below. If this procedure is not successful in indicating the trouble, further tests are provided for troubles which may be caused by singing, near-singing, or poor synchronization.
    a. Sectionalization Tests, Wire Operation. This test is performed under the direction of the control terminal. It is used to locate the source of crosstalk, noise, power hum, singing, and other troubles which appear on the circuit.
    (1) Control terminal tests, (a) Set switch EQPT on 2W.
    (b)	Connect from jacks 2W HYB to Test Set TS-190/U or a magneto telephone.
    (c)	Insert 600-ohm plug in jacks DIR FILT LINE. Note any change in circuit condition. Remove plug.
    (d)	If trouble was heard with plug in jacks, source of trouble is the terminal. (See c(l) below.) If trouble disappears, notify repeater to begin repeater test.
    (2)	Repeater test, (a) While monitoring the circuit, the control terminal should direct the repeater to terminate the adjacent line section with 600 ohms in jacks LINE FILT toward the control terminal. Note any change in circuit condition. Instruct repeater to remove plug.
    (b)	If trouble was heard at control terminal with plug in jacks, its source is the connected equipment at the repeater or terminal installation (protectors, composite sets, line panels, etc.) or the line section. (See c(2) below.) If trouble disappears, continue with repeater test.
    (c)	While monitoring the circuit, the control terminal should direct the repeater to terminate the output to the distant terminal at jacks DIR FILT LINE with 600 ohms. Note any change in circuit condition. Instruct repeater to remove plug.
    (d)	If trouble was heard at control terminal with plug in jacks, its source is the repeater. (See c(l) below.) If trouble disappears, notify the distant terminal to begin distant terminal tests.
    (3)	Distant terminal test, (a) While monitoring the circuit, the control terminal should direct the distant terminal to terminate the line section with 600 ohms in jacks LINE FILT. Note any change in circuit condition. Instruct the distant terminal to remove plug.
    (b) If trouble was heard with plug in jacks, its source is the connected equipment at the repeater or distant terminal installation (protectors, composite sets, line panels, etc.), or in the line section. (See c(2) below.) If trouble disappeared, its source is the distant terminal, since the distant extension has already been checked. (See c(l) below.)
    b. Sectionalization Test—Radio Link Operation. If excessive noise or crosstalk exists on H channels operated over a radio link, it is advisable to check the radio link section of the system first. A majority of troubles encountered will be caused by lack of synchronization between the radio link terminals, or by atmospheric conditions. Once the radio link section of the system is eliminated as a source of trouble, the wire sections may be checked by a procedure similar to that given in subparagraph a above. It should be rembered that coordination between the channels of H carrier and voice-frequency carrier telegraph, if used, is extremely critical, and
    117
    much crosstalk and noise may exist between these channels.
    c. Analysis of Possible Troubles. (1) Terminal and repeater, (a) Noise and power hum. These conditions may be caused by a defective vacuum tube or rectifier. If replacement of the vacuum tubes does not improve the particular condition, check the power supply (par. 103). Noise or power hum originating in the power supply will usually be cleared by replacement of a leaky capacitor or varistor. If trouble still persists after performance of the above checks, the trouble may originate in the amplifier. Check the wiring and circuit components of the amplifier (par. 104).
    (b) Singing. If the terminal or repeater is singing, check to see that the gain controls are on their normal operating settings. If these settings are correct, singing may be caused by a defective feedback circuit in an amplifier, or a defective directional filter. Check these circuits according to directions in paragraphs 104 and 106. If all equipment is in satisfactory condition, see paragraph 98 to determine operating point which will eliminate singing.
    (2) Line section, line equipment, and line filter, (a) Noise and crosstalk. These troubles may be caused by lack of coordination between various carrier systems on the same line. Check that the East-to-West direction of transmission of the system in trouble corresponds to the East-to-West direction of transmission of the other systems on the line. Coordinate the outputs of the various systems so that the power at any point on the line will be approximately the same for all systems. If ringing crosstalk or cross rings are detected, trouble may lie in the incorrect range setting of a voice-frequency ringer. When operating on radio link, if interference is detected between the H carrier channels and the voice-frequency channel, the trouble may be due to poor coordination of outputs on the three channels.
    (b) Power noise, static, and other noise. Static caused by atmospheric or weather conditions will be observed on all lines of the telephone system at the same time. It is impossible to clear this type of trouble completely, but its effect may be reduced by keeping the output of each terminal and repeater as high as possible. Other types of static caused by faulty outside plant construction can be cleared by proper policing and maintenance of the line. Power hum may be caused by power exposures within an installation, but a more common source will be an outside power line running parallel to the carrier line. Its effect may be minimized in the same manner as that described for static. Single frequency
    tones of objectionable magnitude may be caused by singing in an adjacent circuit, by crosstalk paths into an adjacent circuit, or by voice-frequency telegraph or pilot currents in an adjacent circuit. Clearing these troubles is a matter of adjusting levels and remedying troubles which exist in the adjacent circuit. When operating an H system on radio link, some static and noise will be picked up on the radio channels.
    d. Procedure for Clearing Poor Quality. (1) Poor quality of transmission over the system will usually indicate a lack of synchronization between the carrier oscillators at the two terminals. Perform the oscillator synchronization test and adjustment (par. 55) to check whether or not poor synchronization is the cause of poor quality. If it is not, perform the oscillator-frequency adjustment test (par. 110).
    (2)	Poor quality may result from a repeater which is singing. The singing frequency may be outside the audible range. Perform the singing point test of the repeater (par. 98) to determine its singing point. If the requirement of this test is met, and the operating loop gain of the repeater does not exceed 45 db, it is probable that this repeater is not the cause of the trouble.
    (3)	Poor quality may result if the system is not operated at a sufficiently high net loss. First check to see that the circuit is operating at its specified net loss. If the circuit net loss is correct, poor quality may be the result of a faulty directional filter, or poor balance between the compromise network and the two-wire extension. If the filter has been tested (par. 106) and found to be good, and the best possible balance has been obtained between the balancing network and the two-wire extension, perform the terminal singing margin test (par. 98) to determine the highest circuit net loss at which the system may be operated.
    (4)	Poor quality may indicate that the loss-frequency characteristic of the system does not meet the requirements specified in paragraph 56. This condition may be caused by a faulty line section, amplifier, or filter. The attenuation of the open-wire line should be measured for each line section, using frequencies between 3,000 and 11,000 cycles. If the line attenuation is correct at the testing frequencies, it can be plotted to form a curve which rises as the frequency is increased. Excessive humps or peaks in the curve of any line section will indicate that section to be the probable cause of trouble. If the attenuation requirements of the line are met in all line sections, check the amplifiers and filters at each
    118
    terminal and repeater as described in paragraphs 104 and 106.
    98. Singing Tests
    a.	Terminal Singing Margin Test. An 8-db singing margin should be observed at the terminal to insure good quality of transmission, and also to prevent the system from singing if the circuit net loss should change appreciably with changes, in weather conditions. If the terminal sings, it usually will do so at some frequency in the audible range. For this reason the singing margin test of the terminal may be performed with a telephone instead of a measuring set. The procedure for making the test is as follows:
    (1)	Terminate both ends of the circuit in telephone sets with the receivers off the hooks. In switchboard-terminated circuits connect the H carrier circuit to a local extension and remove the telephone receiver from its hook.
    (2)	Test first one terminal, then the other. Note the settings of the TR GAIN and REC GAIN controls in their normal operating conditions. Advance the REC GAIN control four steps (8 db). If no singing is heard, there is a sufficient singing margin. Return the REC GAIN control to its normal setting, and then test the other terminal in the same manner. If the circuit net loss is increased at one terminal to maintain an adequate singing margin, increase it by the same amount at the other terminal in order to keep the same circuit net loss in both directions.
    (3)	Note the reading of the control where singing appears, if singing is heard as the REC GAIN setting is advanced. Back the control off four steps (8 db) from this setting. The new setting will give the highest possible circuit net loss at which the system can be operated without reducing the singing margin. If a lower circuit net loss is desired with an 8 db singing margin still maintained, it can be achieved by improving the balance between the balancing network, and the two-wire extension. Do this by replacing it with a network which is designed to balance the type of extension used. If it is absolutely necessary to obtain a lower circuit net loss than is possible with the balance obtained, the singing margin may be slightly decreased. If this sacrifice is made, the quality of the circuit will be impaired, and it is liable to be unusable at times because of variations in line attenuation.
    b.	Repeater Singing-point Test. Singing will occur unless the losses in the repeater loop equal or exceed the gain of its amplifiers. The repeater singing point is found by advancing the settings of the repeater gain controls until singing takes place or
    maximum gain is reached. If singing takes place at too low a point, there is insufficient loss indicated across one or both of the directional filters.
    (1)	Method. The test is made by watching for an indication on a transmission measuring set of any singing currents which may appear in the repeater when the gain is increased by setting both gain controls near the maximum step. If the repeater does not sing, no appreciable reading should be obtained on the measuring set since no power is fed into the repeater. A slight reading may be ignored for the purposes of this test since such a reading may be due to noise in the repeater or measuring set. A singing condition is not always audible since the singing may occur above the voice-frequency range and, therefore, a measuring set is useful to detect the condition. A singing condition is indicated when an appreciable reading is obtained on the measuring set.
    Caution: At the singing point, the increase in gain may be great enough to damage the measuring set unless an attenuator is used and the measuring set is adjusted to indicate maximum input.
    (2)	Apparatus required:
    1 600-ohm plug.
    1 Decibel Meter TS-399/U.
    1 Attenuator TS-402/U. Patching cords.
    (3)	Procedure, (a) Insert a 600-ohm plug in jacks W DIR FILT LINE.
    (b)	Patch from jacks E DIR FILT LINE to the input jacks of the attenuator. Set the attenuator for 20 db loss.
    (c)	Connect from the output jacks of the attenuator to the input jacks of the measuring set. Adjust the measuring set to indicate maximum input.
    (d)	Note the setting of controls E-W and W-E GAIN, so that they may be returned to their working settings when the test is completed. Then set both gain controls on 40.
    (e)	Advance control E-W GAIN one step. Then, while watching the meter of the measuring set, increase the sensitivity of the measuring set one step at a time until an appreciable reading is obtained, or until maximum sensitivity is reached. If no reading is obtained, readjust the measuring set to indicate maximum input. Then advance control E-W GAIN another step, and repeat the measuring set procedure. Continue the above procedure until a reading is obtained, or step 50 i reached on control E-W GAIN. If no reading is obtained after completing the above procedure, leave the E-W GAIN control on step 50, and advance the W-E GAIN control one step at a time by following the same pro
    119
    cedure until an appreciable reading is obtained. Add gain control settings at which singing began.
    Caution: Always adjust the measuring set to indicate maximum input before advancing the repeater gain control another step.
    (f)	Interchange the 600-ohm plug and the measuring set. Repeat the test. Add the gain control settings at which singing began. Compare this sum with the sum previously obtained, and use the lower of the two as the sum of the gain control settings at which the repeater will sing.
    Requirement: The sum of the gain control settings should equal at least 84 before the repeater begins to sing.
    Note. If the requirements are not met, trouble exists in the amplifiers or directional filters. Check these components according to directions in paragraphs 104 and 106.
    (g)	Reset controls E-W GAIN and W-E GAIN on operating settings; remove patching cords and plugs and restore the circuit to normal.
    99. Trouble Test on Terminal Panel: Wire Operation
    The following test equipment is required for localizing trouble on the terminal panel:
    1 Audio Oscillator TS-379/U.
    1 Decibel Meter TS-399/U.
    1 Attenuator TS-402/U.
    1 Multimeter TS-380/U.
    Patching cords.
    a.	Check of Transmitting and Receiving Circuits. When trouble is known to exist in either the transmitting or receiving circuit, make a test of the other direction of transmission to determine the condition of equipment common to both circuits. See figure 99 for arrangement of testing equipment. If this test definitely locates the trouble in only one circuit, proceed to c or d below.
    (1)	Note the settings of both gain controls, then set the control of the circuit being tested on 50, and the other control on 0.
    *
    2W HYB	DIR
    OR	FILT
    MOD IN*	LINE
    IN	OUT
    H	_	TRANSMISSION
    OSCILLATOR g	CARRIER	ATTENUATOR ZZ^ TnQ/XS g MEASURING
    ■ (A	TERMINAL	(A	SET
    TRANSMITTING CIRCUIT
    INPUT	||	OUTPUT
    EQPT iackr* POWER FREQ	----GAIN'DB--------
    JACKS	JACKS F69T WFQT
    SWITCH	(DBM) (CYCLES)	TERM. TERM
    2W	2W HYB	0	1,000	DIR	21.0	213
    --------------------------------------- FILT -----------------------
    4W TEL	MOD IN	4-4	1,000	LINE	16 0	16.3
    2W HYB*	DIR
    OR *	FILT
    MOD OUT	LINE
    0U1 IN	_______________
    TRANSMISSION	H
    MEASURING g	CARRIER	£ZZ ATTENUATOR ZZY	gOSClLLATOR
    SET	TERMINAL	"(( »
    ______________
    RECEIVING CIRCUIT ___________ INPUT____________________________OUTPUT_________________ DIR FILT POWER FREQ EQ PT______________* GA- - P ___________________
    LINE JACKS (DBM)	(CYCLES) SWITCH JACKS	EAGJ	TeVJ
    EAST TERM. -20	6,000 2W 2W HYB 170	16.6
    WEST TERM. -20	8,000	4W TEL DEM OUT 27.9	275
    Ti -»»aoi - •
    Figure 99. Terminal gain test.
    120
    (2)	Adjust the frequency and input level of the oscillator as specified under INPUT. Patch this testing power to the proper jacks.
    (3)	Measure the output of the terminal at the jacks specified under OUTPUT.
    Requirement: The measured gain will be within ±3.5 db of the specified gain.
    (4)	Remove the patching cords and restore the gain controls to their normal settings.
    (5)	If the requirements are not met for both directions of transmission, trouble is indicated in equipment common to both circuits. Proceed to b below.
    (6)	If the requirements are met in one direction of transmission and not in the other, proceed to c or d below for tests of the circuit which is in trouble.
    b.	Trouble in Both Transmitting and Receiving Circuits. (1) Check power supply voltages (fig. 100). If output voltages do not meet requirements, see paragraph 103. If voltages meet requirements, proceed with (2).
    (2)	Check the oscillator output (par. 48). If re
    quirements are not met, see paragraph 105. If requirements are met, proceed with (3).
    (3)	Check the wiring, connections, and the remaining common equipment, consisting of jacks, switches, directional filter, and hybrid coil.
    (4)	If these tests do not disclose the trouble, perform tests described in c and d below. Tests should be performed both for the transmitting and receiving circuits since there may be trouble in both circuits.
    c.	Trouble in Transmitting Circuit. (1) Replace vacuum tube TR and check circuit.
    (2)	Check TR tube socket voltages (fig. 100).
    (3)	Check the transmitting amplifier (par. 104).
    (4)	Check the oscillator output as described in paragraph 48 but note that the output measurement is made between the center tap of transformer MOD OUT and ground.
    (5)	Check wiring, connections, and all equipment not previously checked.
    d.	Trouble in Receiving Circuit. (1) Replace vacuum tube REC and recheck circuit.
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    NOTEH.THE TUBE SOCKETS ARE VIEWED FROM THE REAR OR WIRING SIDE OF THE EQUIPMENT.
    2.TUBE SOCKET TERMINALS ARE NUMBERED CONSECUTIVELY FROM ONE TO SIX IN A CLOCKWISE DIRECTION. TERMINAL 1 IS ADJACENT TO THE SMALL LOCATING HOLE IN THE BOTTOM OF THE TUBE SOCKET.
    3.ALL VOLTAGES ARE MEASURED BETWEEN THE NUMBERED TERMINAL AND GROUND-
    IS SYMBOL FOR FIXED CAPACITOR.
    Figure 100. Tube socket and power supply voltages, terminal panel.
    121
    (2)	Check REC tube socket voltages (fig. 100).
    (3)	Check the receiving amplifier (par. 104).
    (4)	Check the oscillator output as described in paragraph 48 but note that the output measurement is made between the center tap of transformer DEM IN and ground.
    (5)	Check wiring, connections, and all equipment not previously checked.
    100.	Trouble Tests on Terminal Panel: Radio Link
    Operation
    Trouble localization on two terminals connected for radio link should be preceded by an analysis of trouble symptoms. If one terminal only is in trouble, set its LINE switch on one of the WIRE positions, and perform the terminal tests described in paragraph 99. If both circuits of the terminal meet test requirements, trouble lies in the switches, interpanel connections, or in the BF or DF filters of the other terminal panel. Perform the terminal tests on the other terminal. If the other terminal also meets test requirements, the trouble lies in the interpanel connections or in the RADIO setting of the LINE switch on the terminal in trouble. If both terminals are reported in trouble at the same time, the common equipment which may be suspected includes the directional filters, jacks, LINE switches, line connections, and the external source of power.
    101.	Trouble Tests on Repeater Panel
    The following test equipment is required for localizing trouble on the repeater panel:
    1 Audio Oscillator TS-379/U.
    1 Decibel Meter TS-399/U.
    1 Attenuator TS-402/U.
    1 Multimeter TS-380/U.
    Patching cords.
    a.	Check of Circuits in Both Directions of Transmission. When trouble is known to exist in either the East-to-West or the West-to-East circuit, make a test of the other direction of transmission to determine the condition of equipment common to both circuits. See figure 101 for arrangement of testing apparatus. If this test definitely locates the trouble in only one circuit, proceed to c below.
    (1)	Note the settings of both gain controls, then set the control of the circuit being tested on 50, and the other control on 0.
    (2)	Adjust the frequency and input level of the oscillator as specified under INPUT. Patch this testing power to the proper jacks.
    (3)	Measure the output of the repeater at the jacks specified under OUTPUT.
    Requirement: The measured gain will be within ±2.5 db of the specified gain.
    (4)	Remove the patching cords and restore the gain controls to their normal settings.
    (5)	If the requirements are not met for both directions of transmission, trouble is indicated in equipment common to both circuits. Proceed to b below.
    (6)	If the requirements are met in one direction of transmission and not in the other, proceed to c below for tests of the circuit which is in trouble.
    e (or w) DIR
    w (or e)
    DIR
    FILT	FILT
    IN	OUT	UNE --------------JNE
    ,	H	TRANS-
    OSCILLATOR	ATTENUATOR v	v	CARRIER	v	° MISSION
    ---------------------------------------------- repeater	Measuring W	W------------W SET
    DIRECTION	INPUT			OUTPUT
    	JACKS	POWER (DBM)	, FREQ (CYCLES)	JACKS	GAIN (DB)
    E-W	E DIR FILT LINE	. -25	8,000	W DIR FILT LINE	31
    W-E	W DIR FILT LINE	-25	6,000	E DIR FILT LINE	32
    Figure 101. Repeater gain test.
    TL 5O5O2-f
    122
    b.	Trouble in Both Directions. (1) Check the power supply voltages (fig. 102). If output voltages do not meet requirements, see paragraph 103. If voltages meet the requirements, proceed with (2).
    (2)	Check the wiring, connections, and the remaining common equipment, consisting of the jacks and directional filters.
    (3)	If these tests do not disclose the trouble, follow the directions in c below for testing each direction of tranmission individually.
    c.	Trouble in One Direction Only. (1) Replace the vacuum tube and recheck the circuit.
    (2)	Check the tube socket voltages (fig. 102).
    (3)	Check the amplifier (par. 104).
    (4)	Check wiring, connections, and all equipment not previously checked.
    102.	Trouble Tests on Line Panel
    a.	Check wiring and connections.
    b.	Check characteristics of line filter LF (par. 106).
    c.	The balancing networks and varistor may be checked by substitution of parts known to be good.
    103.	Trouble in Power Supply
    The information in this paragraph is applicable to the power supply at either the terminal or repeater.
    a.	Check the output voltages (fig. 100 or 102).
    b.	If requirements are met, check wiring between measuring point and tube sockets.
    c.	Perform power supply adjustment if voltages measured do not meet requirements (par. 46).
    d.	If no output is measured from the filament winding and the d-c supply, trouble is indicated on the primary side of the PWR transformer. Check or replace the power cord and the transformer.
    e.	If no output is measured from the filament winding, the winding may be defective, or may be open at the repeater resistor R6. Replace the defective part.
    /.If the d-c output is low or no output is measured between terminal 4 of coil P and ground, check the capacitors and replace if necessary. If one varistor is found to be defective both varistors should be replaced in order to preserve the electrical characteristics of the varistor bridge.
    CATHODE
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    NOTE: 1.THE TUBE SOCKETS ARE VIEWED FROM THE REAR OR WIRING SIDE OF THE EQUIPMENT.
    2.TUBE SOCKET TERMINALS ARE NUMBERED CONSECUTIVELY FROM ONE TO SIX IN A CLOCKWISE DIRECTION. TERMINAL 1 IS ADJACENT TO THE SMALL LOCATING HOLE IN THE BOTTOM OF THE TUBE SOCKET.
    3. ALL VOLTAGES ARE MEASURED BETWEEN THE NUMBERED TERMINAL AND GROUND EXCEPT THE VOLTAGE MEASURED BETWEEN TERMINALS 9ANDIO OF PWR TRANSFORMER.
    IS SYMBOL FOR FIXED CAPACITOR.	TL 51514
    Figure 102, Tube socket and power supply voltages, repeater panel.
    123
    104.	Trouble in Amplifiers
    This paragraph covers trouble location procedures for a defective amplifier at a terminal or repeater, and also includes a test of the amplifier gain.
    Note. When making tests of the amplifier other than voltage measurements or the amplifier gain test, be sure to disconnect the wires running to the external source of power.
    a. Trouble Location. (1) Check the condition of the amplifier tube.
    (2)	Recheck all socket voltages.
    (a)	Incorrect filament voltage may be caused by wiring defects.
    (b)	Incorrect plate or screen voltages may be caused by defective resistors or capacitors in the amplifier, defective wiring, or by a defect in the windings of the OUT transformer. Examine all wiring and connections carefully, and check or replace all components of the amplifier.
    b.	Amplifier Gain Test (fig. 103). This test is used to check the amplifier gain after a defective part has been replaced, or it may be used as a further trouble location test after the socket voltages have been checked and found to be within limits.
    (1)	The test is made by first removing existing connections from the primary of transformer IN and secondary of transformer OUT. Testing power at the proper level is then connected to the primary of transformer IN and the amplifier gain is measured by connecting a measuring set to the secondary of transformer OUT. Oscillator output level and frequency, and attenuator setting are specified on figure 103.
    (2)	The following test equipment is required:
    1	Audio Oscillator TS-379/U.
    1	Attenuator TS-402/U.
    1 Decibel Meter TS-399/U.
    Patching cords.
    (3)	Make the test in the following manner:
    (a)	Set the attenuator for the specified loss.
    (b)	Connect the test equipment to the amplifier.
    (c)	Adjust the oscillator as specified.
    (d)	Determine the gain of the amplifier.
    Requirement: The measured gain will be within ±2.0 db of the specified gain.
    (4)	If the gain is too high and the power supply is adjusted properly, it is probable that there is trouble in the feedback circuit. If the gain is too low and the power supply is adjusted properly, loose connections or defective coupling transformers may be the cause of the trouble.
    105.	Trouble in Oscillator
    This paragraph covers trouble location in the oscillator when no output is measured or when the output is outside limits specified previously.
    a. Trouble Procedure. (1) Be sure that a good tube has been placed in the socket.
    (2)	Check the tube socket voltages (fig. 100).
    (a)	Incorrect filament voltage may be caused by wiring defects.
    (b)	Incorrect plate or screen voltages may be caused by defective resistors or capacitors in the oscillator circuit, defective wiring, or by a defect in the windings of the OSC transformer. Examine all wiring and connections carefully, and check or replace all circuit components.
    (3)	Adjust the oscillator frequency (par. 110) when the trouble has been remedied.
    106.	Trouble in Filters
    If any of the localization tests indicate that a filter may be in trouble, its condition may be checked by
    ------------ —---------------------------	r-	0UT	------------
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    OSCILLATORg	ATTENUATOR	g I |g AMPLIFIER sllfe
    Mw	Y) ft X	<4-J	L~>	/	(( OMtAoUHING
    OSCILLATOR ATTEN- AMPLR INPUT AMPLR OUTPUT GAIN
    AMPLIFfER output 'I'FREQ UATOR --------------------------------- ^ENT^
    ____________(DBM) (CYCLES) SETTING EQUIP TERMS EQUIP TERMS  TERM. XMTG__0	B.000	25	TR IN	i & 2	TROUT	3 &. 4	33	0±2
    TERM RCVG	O	i.OOO	2 5	REC IN	i&3	REC OUT	142	32	0+2
    REPTR E-W	O	8,000	25	E-WIN	'42	E-WOUT	3&4	33	0+2
    REPTR W-E	O	6,000	2 5	W-E IN	i&2	W-EOUT	3& 4	33	0+2
    'L SI29I
    Figure 103. Amplifier gain test.
    124
    the tests listed in this paragraph. The following test equipment is necessary:
    1 Audio Oscillator TS-379/U.
    1 Decibel Meter TS-399/U.
    1 Multimeter TS-380/U.
    Patching cords.
    a.	Disconnect all wiring to the terminals of the filter under test (table XVI).
    b.	Using the lowest ohms scale of the multimeter, measure between each of the terminals mentioned in table XVI and ground.
    (1)	On any filter except the carrier section of line filter LF continuity between any terminal and ground indicates that the filter should be replaced. A ground will seriously affect the characteristics of the filter.
    (2)	The carrier or high-pass section of line filter LF is unbalanced to ground. The grounded side is brought out to terminal 4 of terminal strip A.
    c.	Check the frequency characteristic of the filter in the following manner:
    (1)	Connect the oscillator and measuring set to the terminals indicated in table XVI as shown in figure 104.
    (2)	Measure the loss of the filter for each of the frequencies specified.
    Note. The calibrations of both the oscillator and the measuring set must be accurate at all times during the test. Check them frequently.
    (3)	If the filter does not meet any one of the minimum requirements in the table, it is defective. Replace it.
    (4)	Turn to paragraph 111 for directions on returning the system to service after a filter is replaced.
    107.	Troubles in Potentiometers, Switches, and Jacks
    All tests specified in this paragraph may be made with Multimeter TS-380/U.
    a.	Potentiometers. The potentiometers at the terminal and repeater are identical. They are constant impedance, adjustable T-type pads, with the bottom of the T grounded. The condition of any potentiometer may be checked by performing the applicable gain measurement test described in section V. The measurement should change approximately 2-db per step as the potentiometer is rotated. If this requirement is not met, first check the external wiring of the potentiometer, and if no trouble is found, remove the potentiometer from the subpanel and repair or replace it.
    b.	Switches. If a switch is suspected of causing trouble, determine its condition by repeating the gain checks of the terminal transmitting and receiving circuits with the two switches on the following settings:
    EQPT.	' LINE
    2W	WIRE EAST
    2W	WIRE WEST
    4W TEL	WIRE EAST
    If the terminal is set for radio link operation, the switches are tested in the prescribed wire positions. If the gain requirement for any switch setting is not met, check the setting for continuity. If the requirement is not met, check the switch for dirty or open contacts or mechanical failure. If the requirement is met, wiring connections to the switch may be defective.
    c.	Jacks. To check the condition of the jack perform a continuity test between the two connected jack terminals located at the rear of the panel. Continuity through the jacks should be broken and made by inserting and removing a plug.
    zO( ° filter	_________________
    /	UNDER
    o 5^	/° TEST	o	©TRANSMISSION
    ncrniA-rno W/	\	\	MEASURING
    OSCILLATOR	/	\ I	SET
    o J	o	°
    --r	O	\	/
    F	O
    TL 51293
    Figure 104. Filter test.
    125
    Table XVI. Filter characteristics
    Filter test	Test connections				Input frequency (kc)	Loss requirement (db)
    	Oscillator to		Measuring set to
    	Equip.	Term.	Equip.	Term.
    Terminal panel
    LP: (Xmtg side) (Rcvg side)	LP LP	3 and 4 9 and 10 -	LP LP	1 and 2 1 11 and 12	1.0 3.0 4.0 10.0 1.0 15.0	4.0 or less 3.0 or less 12.0 or more 30.0 or more 2.0 or less 24.0 or more
    BF: (High-pass) (section) (Low-pass) (section)	BF BF	1 and 2 9 and 10	BF BF	3 and 4 11 and 12	6.5 8.0 10.0 15.0 6.0 8.0 12.0	18.0 or more 2.0 or less 2.0 or less 18.5 or more 1.5 or less 25.0 or more 18.0 or more
    DF (E DF) 2 (High-pass) (section) (Low-pass) (section)	DF (E DF) DF (E DF)	5 and 6 3 and 4	DF (E DF) DF (E DF)	1 and 2 1 and 2	6.5 7.0 9.0 13.0 3.0 5.0 6.5 7.5 12.5	45.0 or more 7.0 or more 2.5 or less 45.0 or more 15.0 or more 2.0 or less 3.0 or less 20.0 or more 45.0 or more
    Repeater panel
    E DF 2 (See test on DF of terminal panel): W DF (High-pass)	W DF W DF	3 and 4 5 and 6	W DF W DF	1 and 2 1 and 2	6.5 7.0 9.0 15.0 3.6 5.0 7.5 9.0	24.0 or more 6.0 or more 2.0 or less 35.0 or more 9.0 or more 2.0 or less 12.0 or more 38.0 or more
    Line panel
    LF: (Carrier section) (Voice section)	Term. Strip A Term. Strip A	3 and 4 5 and 6	Term. Strip A Term. Strip A	1 and 2 1 and 2	3.4 4.0 5.0 1.0 3.0 4.0	18.0 or more 4.5 or less 1.5 or less 1.0 or less 4.5 or less 40.0 or more
    1 Remove resistor between these terminals before making test.
    2 Directional filter E DF at the repeater is identical to directional filter DF provided at the terminal.
    Section XVI.
    REPAIRS
    108.	Replacement of Parts
    With the exception of jacks, gain controls, and switches, no particular difficulty should be encountered in the removal and replacement of parts contained in H carrier equipment. The replacement of
    jacks, gain controls, and switches involves the removal of the bakelite subpanel, described in section XII.
    109.	Use of Tools and Repair Equipment
    a.	General. Important items in the clearing of
    126
    trouble are maintaining cleanliness in the equipment, care in the use of tools, accuracy when making adjustments, and care in handling equipment.
    b.	Cleanliness. (1) Keep the apparatus clean. Contact trouble is caused mainly by dust and lint lodging between the contact surfaces of the multiple contact switches and jacks.
    (2)	Take care not to break the wires connected to the multiple contact switches when working on the terminal and repeater panels. These are the GAIN potentiometers at the repeater and terminal and also the LINE and EQPT switches at the terminal. Since these switches are in the transmission path, a loose connection or a collection of dirt and lint on any of them will cause noise in the circuit or may cause an open in the transmission circuit.
    (3)	The multiple contact switches and jacks are not provided with covers. Take care not to allow dust and lint to fall on the spring contacts of the jacks nor on the contacts of the switches when working on equipment.
    (4)	Keep the doors on the front and rear of the equipment cabinets closed except when working on the equipment, in order to reduce as much as possible the chance for trouble from dirt and lint.
    c.	Soldering. Use care in making wiring changes, or in the clearing of troubles such as wiring crosses or opens, and when removing or replacing a piece of apparatus, in order to avoid introducing potential wiring troubles. Properly soldered connections are important. A properly soldered joint should be sound with not too much solder. Adequate clearance should be provided between adjacent terminals so that vibration will not cause crosses. Take extreme care to see that no loose bits of wire or solder are left between the wiring terminals, among the wires, or in the apparatus housings after soldering operations. Protect the apparatus immediately below from solder particles or bits of wire during the above operations. Use a piece of cotton duck or similar material for protection. Always use a soldering iron holder to avoid a possible fire hazard.
    d.	Repair Equipment. No special repair equipment is required to aid in the replacement of any of the H carrier equipment. If the tools supplied with the office tool set are used properly and carefully it will be possible to perform all repairs necessary.
    110.	Oscillator Frequency Adjustment (fig. 105)
    This adjustment is used to set the oscillator frequency after a defective oscillator component has been replaced, or after performance of the synchronization test has indicated that the terminal oscillators are out of adjustment. Make the test by unbalancing
    transformer MOD OUT to increase the carrier leak, then measure this leak on the receiving side of the terminal at the low-pass output side of band filter BF. The following test equipment is required:
    1 decibel meter TS-399/U.
    600-ohm plug. ' Patching cords.
    a.	Note the setting of switch LINE and set it on RADIO TRANS.
    b.	Note the setting of controls TR GAIN and REC GAIN. Set TR GAIN on 50 and REC GAIN on 44.
    c.	Strap between terminals 5 and 6 of transformer MOD OUT at the back of the panel. This transformer is located at the top right of the panel.
    d.	Connect terminal 5 to 7 and 9 to 11 on terminal strip B.
    e.	Terminate jacks DIR FILT LINE with a 600-ohm plug.
    f.	Connect the terminals of the measuring set to terminals 3 and 4 of terminal strip B.
    g.	Adjust the measuring set to obtain an indication.
    h.	Loosen the fiber tube on the back of the OSC transformer, located on the rear of the panel in the upper left corner. Using a screwdriver, adjust the screw inside the fiber tube until the highest possible output reading is obtained on the measuring set. The oscillator is generating the correct carrier frequency when the screw is set for maximum output. If no peak reading can be obtained, some part of the oscillator circuit is in trouble; follow the procedure given in paragraph 105.
    i.	After the oscillator frequency has been adjusted properly, tighten the fiber tube, and disconnect the measuring set. Remove straps on terminal strip B and on MOD OUT transformer. Restore the LINE switch and the GAIN controls to normal operating positions.
    j.	Perform synchronization test (par. 55).
    III.	Procedure for Returning System to Service
    a.	After repairs, replacement of parts, or adjustments have been made on H carrier equipment which may affect the over-all system line-up, check the entire system before it is returned to service.
    b.	Ascertain that all switches and controls are on their proper operating settings.
    c.	Perform the power supply adjustment if the output voltages of the power supply have been affected (par. 46).
    d.	Check the voltages at all tube sockets (figs. 100 and 102).
    e.	If any tubes have been replaced that satisfac-
    127

    MOD
    DIR FILT linf
    MOD OUT
    TR GAIN (50)
    TRANSMISSION MEASURING SET
    7,400
    6,900 Qj
    TERM. STRIP
    REC GAIN
    INSTRUCTIONS
    NOTE SETTINGS OF LINE SWITCH AND GAIN
    CONTROLS, THEN RESET AS SHOWN
    STRAP THE TERMINALS ON TERMINAL STRIP
    B AND TRANSFORMER MOD OUT AS
    SHOWN
    INSERT 600-0HM PLUG IN JACKS DIR FILT
    LINE.
    N. CONNECT TRANSMISSION MEASURING SET TO
    TERMINAL STRIP B AS SHOWN.
    5. ADJUST MEASURING SET FOR READING.
    LOOSEN FIBER TUBE OH REAR OF TRANSFORMER OSC.
    7. ADJUST OSC ADJUSTMENT SCREW UNTIL HIGHEST POSSIBLE OUTPUT READING IS
    OBTAINED ON MEASURING SET.
    8. TIGHTEN FIBER TUBE.
    LINE SWITCH AND GAIN CONTROL SETTINGS
    600 n. PLUG
    REC GAIN (44)
    TR GAIN
    6. REMOVE STRAPS AND MEASURING SET CONNECTIONS, ANO RESTORE LINE SWITCH
    AND GAIN CONTROLS TO NORMAL OPERATING SETTINGS.
    TL5I292
    Figure 105. Oscillator frequency adjustment.
    torily passed test requirements, retain these tubes as spares.
    f.	Perform the oscillator synchronization test if the output of the oscillators has been affected (par. 55).
    g.	Make a circuit net loss measurement in each direction.
    h.	Perform a detailed system line-up if the above
    measurement indicates that the system is lined up incorrectly.
    i.	Perform the channel frequency net loss test if any filters have been replaced.
    j.	Ring, talk, and listen on the system from its terminations.
    k.	If system performance is satisfactory return it to service.
    APPENDIX I
    LIST OF COMPONENT PARTS
    Note. This list is for general information only. See appropriate publications for information pertaining to requisition of spare parts.
    I. Component Parts of Carrier Terminal OA-I3/FC
    Quantity	Component part
    1	Carrier Terminal OA-13/FC (Western Electric Co X-66217A).
    4 6 1 2 sets	Designation cards. Vacuum Tube JAN-310A (spares). TM 11-2025. Drawings: B-400044-1, sheet 1, carrier terminal panel schematic diagram. B-400044-1, sheet 2, carrier terminal panel schematic diagram. B-400044-2, carrier terminal panel wiring diagram.
    2. Component Parts of Carrier Repeater OA-IO/FC
    Quantity	Component part
    1	Carrier Repeater OA-IO/FC (Western Electric Co X-66217B).
    4 6 2 sets	Designation cards. Vacuum tube JAN-310A (spares). Drawings: B-400045-1, repeater panel schematic diagram. B-400045-2, repeater panel wiring diagram.
    3. Component Parts of Carrier Filter F-36/FC
    Quantity	Component part
    1	Carrier Filter F-36/FC (Western Electric Co X-66217C).
    200 ft 5 ft 4 1 2 sets	20-ga wire, black and black-red. 22-ga wire, shielded slate and slate-red. Designation cards. TM 11-2025. Drawings: B-400046-1, line filter and balance network panel schematic diagram. B-400046-2, line filter and balance network panel wiring diagram.
    128
    APPENDIX II
    MAINTENANCE PARTS
    I.	Maintenance Parts for Carrier Terminal OA-I3/FC
    The following information was compiled on 30 March 1945. The appropriate section of the ASF Signal Supply Catalog for Carrier Terminal OA-13/FC is:
    Fixed Plant Maintenance List: SIG 10-840.38, Carrier Terminal OA-13/FC.
    For the latest index of available catalog sections, see ASF Signal Supply Catalog SIG 2.
    Note. The following list covers station stock maintenance parts.
    Ref. symbol	Signal Corps stock No.	Name
    Cl, CIO, CH	3DB2-958	CAPACITOR
    C2, C4	3DB 1.962-1	CAPACITOR
    C3	3DA10-158	CAPACITOR
    C6	3DA3-34	CAPACITOR
    C8, C9	3DB5-12.1	CAPACITOR
    Pl, P2	3H4956-54	RECTIFIER
    R3	3Z6580-26	RESISTOR
    R4, R5, R10	3Z6500-87	RESISTOR
    R6	3Z6065-4	RESISTOR
    R7, Rll	3Z6801-80	RESISTOR
    R8	3Z6050-133	RESISTOR
    R9	3Z6100-162	RESISTOR
    R12	3Z6060-36	RESISTOR
    OSC, REC, TR	2J310A	TUBE, vacuum
    DEM, MOD	4Z9715	VARISTOR
    2.	Maintenance Parts for Carrier Repeater OA-IO/FC
    The following information was compiled on 30
    March 1945. The appropriate section of the ASF Signal Supply Catalog for Carrier Repeater OA-IO/FC is:
    Fixed Plant Maintenance List: SIG 10-840.39, Carrier Repeater OA-IO/FC.
    For the latest index of available catalog sections, see ASI? Signal Supply Catalog SIG 2.
    Note. The following list covers station stock maintenance parts.
    Ref. symbol	Signal Corps stock No.	Name
    Cl, C2	3DB5-12.1	CAPACITOR
    C3, C5	3DA10-1S8	CAPACITOR
    C4, C6	3DB 1.962-1	CAPACITOR
    Pl, P2	3H4956-54	RECTIFIER
    Rl, R3	3Z6500-87	RESISTOR
    R2, R4	3Z6065-4	RESISTOR
    RS	3Z6801-80	RESISTOR
    R6	3Z5985-4	RESISTOR
    E-W, W-E	2J310A	TUBE, vacuum
    3.	Maintenance Parts for Carrier Filter F-36/FC
    The following information was compiled on 30 March 1945. The appropriate section of the ASF Signal Supply Catalog for Carrier Filter F-36/FC is :
    Fixed Plant Maintenance List: SIG 10-840.40, Carrier Filter F-36/FC.
    For the latest index of available catalog sections, see ASF Signal Supply Catalog SIG 2.
    129
    APPENDIX III
    REFERENCES
    I.	Parts List
    SIG 1, Introduction to ASF Signal Supply Catalog.
    SIG 2, Complete Index to ASF Signal Supply Catalog.
    SIG 3, List of Items for Troop Issue.
    SIG 4-1, Allowances of Expendable Supplies.
    SIG 5, Stock List of All Items.
    SIG 10, Fixed Plant Maintenance List.
    SB 11-10, Signal Corps Kit and Materials for Moisture- and Fungi-resistant Treatment.
    2.	Technical Manuals on Associated Equipment and Test Equipment
    TM 11-2021, Ringers TA-38/FC and TA-39/FC (Voice-frequency Ringer Packaged Equipment).
    TM 11-2026, Type C Carrier Telephone Packaged Equipment, Moisture-resistant (Carrier Terminals OA-ll/FC and OA-12/FC, Carrier Repeater OA-9/FC, and Carrier Filter F-37/FC).
    TM 11-2028, Voice-Frequency Telephone Repeater Packaged Equipment, Moisture-resistant (Telephone Repeaters OA-7/FC and OA-8/FC).
    TM 11-2029, Voice-frequency Carrier Telegraph Packaged Equipment (Carrier Terminals OA-4/FC and OA-5/FC).
    TM 11-2039, 19C (SPL) Oscillator (Audio Oscillator TS-379/U).
    TM 11-2042, Volt-ohm-milliammeter per D-166852 (Multimeter TS-390/U).
    TM 11-2044, 5A (SPL) Attenuator (Attenuator TS-402/U).
    TM 11-2045, 13A (SPL) Transmission Measuring Set (Decibel Meter TS-399/U).
    TM 11-2046, 67B and 68B (SPL) Test Sets (Test Set TS-190/U)-.
    TM 11-2047, Hickok Model 560 (SPL) Tube Tester (Tube Tester 1-171).
    3.	Shipping Instructions
    U. S. Army spec No. 100-14A Army-Navy
    General Specification for Packaging and Packing for Overseas Shipment.
    4.	Decontamination
    TM 3-220, Decontamination.
    5.	Demolition
    FM 5-25, Explosives and Demolitions.
    6.	Other 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.
    TB SIG 13, Moistureproofing and Fungi-proofing Signal Corps Equipment.
    TM 1-455, Electrical Fundamentals. •
    TM 11-473, Central Office Maintenance.
    TM 11-475, Principles of Long Distance Telephone and Telegraph Transmission.
    TM 11-486, Electrical Communication Systems Engineering.
    TM 11-487, Electrical Communication Systems Equipment.
    TM 11-755, Grounds and Grounding for Wire Equipment.
    TM 11-2022, Application of Fixed Plant Packaged Equipment to Open-Wire Lines.
    TM 11-2037, Installation, Operation, and Maintenance of Open-Wire Offices Packaged Equipment.
    TM 37-250, Basic Maintenance Manual.
    7.	Forms
    WD AGO Form 468, Unsatisfactory Equipment Report.
    Army Air Forces Form 54, Unsatisfactory Report.
    8.	Abbreviations
    ac ................alternating current (noun)
    a-c ...............alternating-current (adjective)
    amp ...............ampere(s)
    amplr .............amplifier
    130
    131
    approx ...........approximately
    AWG ..............American Wire Gauge
    bal ..............balancing
    cap ..............capacitor
    carr .............carrier
    chan .............channel (s)
    ckt ..............circuit
    Ctrl .............control
    ex ...............composite telegraph circuit or set
    db ...............decibel (s)
    dbm ..............power in decibels referred to 1 milliwatt
    de ...............direct current (noun)
    d-c ..............direct-current (adjective)
    dem ..............demodulator
    dir ..............directional
    dwg ..............drawing
    E ................East
    equip ............equipment
    fig ..............figure
    fil ..............filter
    freq .............frequency
    ga ...............gauge
    gnd ..............ground
    hyb ..............hybrid
    kc ...............kilocycle (s)
    M ................thousand
    meg ..............megohm(s)
    mf ...............microfarad(s)
    mi ...............mile(s)
    mod ..............modulator
    mtg ..............mounting
    net ..............network
    No ...............number
    osc ..............oscillator
    ph ...............phantom
    pot ..............potentiometer
    prot .............protector (s)
    pwr ..............power
    revg .............receiving
    revr .............receiver
    reptr ............repeater
    reqd .............required
    res ..............resistor
    rptg .............repeating
    sb ...............switchboard
    sec ..............section
    sig ..............signal
    so ...............socket
    sw ...............switch
    sx ...............simplex telegraph circuit
    term .............terminal
    tg ...............telegraph
    tp ...............telephone
    transf ...........transformer
    v ................volt(s)
    v-f ...............voice-frequency	(adjective)
    vt ...............vacuum tube
    W ................West
    w ................watt(s)
    xmtg .............transmitting
    xmtr ............transmitter
    z ................impedance

    INDEX
    Paragraph Page
    Abbreviations ...........................  App.	Ill 130
    Adjustments:
    Gain (tables V and VI)......................36	39
    Oscillator frequency (fig. 105)............110	126
    Synchronization (figs. 56 and	57)..........55	68
    Transmitting output (fig. 52)...............51	65
    Voltage: Detailed ...................................  46	61
    Preliminary ............................32	38
    Amplifiers:
    Procedure for locating trouble.............104	123
    Receiving gain measurement..................49	62
    Receiving amplifier REC....................80c	95
    Repeater gain measurement...................52	65
    Transmitting amplifier TR..................79c	94
    Transmitting gain measurement...............50	63
    W-E and E-W amplifiers..................5a,	88c	6,104
    Application: Open-wire	pair	(fig. 2)..................lb	1
    Phantom group	(figs.	13 to 15)...........10	12
    Physical circuit (fig. 12)..........«........9	12
    Radio link	(fig.	16)......................11	14
    System ......................................8	12
    Telegraph ..............................9b,	106	12,14
    Associated equipment .......................la,	25	1, 28
    Attenuation of open-wire lines (table II)... 14a, 17a	18, 20
    Attenuation of open-wire lines, measuring......97d	117
    Auxiliary equipment (not used).
    Balancing networks ..........................6,906	10,110
    External ...................................39	40
    Band-pass filter BF (fig. 79)........79c,	806, 856	94,97
    Cable, intermediate and	entrance (fig.	17)......15	19
    Cards, designation (fig.	59)..............57a	71
    Carrier circuit transfer..............;.....3c,	41	2,45
    Carrier leak suppression circuit (fig.	78)......80	94
    Carrier line filter. (See Line filter.)
    Channel net:
    Loss-frequency test (fig. 58)...............56	70
    Loss measurement (fig. 62)..................59	73
    Characteristics, electrical (table I)............7	10
    Checks:
    Circuits in both directions of transmission, repeater ...........................101a	121
    Equipment performance (table X).............58	73
    Four-wire extensions ......................94c	113
    System performance ........................>42	53
    Paragraph Page
    Checks—Continued :
    Transmitting and receiving circuits, ter-
    minal ..................................99a	119
    Two-wire extensions	and terminations....946	113
    Vacuum tube ...............................33	39
    Circuit descriptions, terminal:
    Four-wire .................................4c	6
    Radio link ................................4d	6
    Two-wire:
    Receiving .............................46	4
    Transmitting ........................  4a	4
    Component parts:
    Carrier Filter F-36/FC.................App. I	128
    Carrier Repeater OA-10/FC..............App. I	128
    Carrier Terminal OA-13/FC..............App. I	128
    Components, major ............................. 2	2
    Connecting arrangements .......................37	40
    Connections and adjustments, outline...........29	34
    Connections:
    Carrier transfer ..........................41	45
    Physical circuit with voice-frequency telephone repeater and composite telegraph (figs. 43 and 44).
    Physical circuit with composite telegraph (figs. 45 and 46).
    Physical circuit with simplex telegraph (figs. 47 and 48).
    External	balancing networks..............39	40
    Ground ...................................30	35
    Line .....................................40	45
    Physical circuit with voice-frequency telephone repeater and composite telegraph (figs. 36 and 37).
    Physical circuit with composite telegraph (figs. 38 and 39).
    Physical circuit with simplex telegraph (figs. 40 and 41).
    Radio link (fig. 42).
    Power .....................................31	37
    Repeater (fig. 32).
    Terminal, wire operation (fig. 31).
    Terminating ...............................38	40
    Connection of two type H carrier terminals on a four-wire basis (fig. 35).
    Four-wire (fig. 34B).
    Two-wire (fig. 34A).
    Coordination (fig. 19).....................20,166	23,20
    Crosstalk .................................16,97c 19,117
    133
    134
    Paragraph Page
    Paragraph Page
    Dbm, definition ..............................7e
    Demodulator ..................................80c
    Description of type H carrier system:
    General (fig. 1).....................:......1
    Physical ...................................3
    Carrier Filter F-36/FC (fig. 5)........3c
    Carrier Repeater OA-IO/FC (fig. 4)....36
    Carrier Terminal OA-13/FC (fig. 3)...3a
    Designation cards (fig. 59)..................57a
    Diagrams ......................................93
    Schematic:
    12	Functioning of equipment:
    95	Detailed ....................................77
    Carrier Filter F-36/FC (line panel)....90
    (see	Line	filter	LF (fig.	93)...........90a
    frontispiece)	Line	filter	network LFN	(figs.
    2	94	and	95)......................90a
    2	Line	filter	balancing	unit LFB....90ft
    2	Line filter balancing network
    LF BN '...........................906
    71
    z	Phantom line filter balancing
    112	network PH LF BN................90ft
    Carrier line panel, drawing B-400046-1
    Carrier repeater panel, drawing B-400045-1
    Carrier terminal panel, drawing B-400044-1
    Transmission (fig. 18)....................18
    Wiring:
    Carrier line panel, drawing B-400046-2
    Carrier repeater panel, drawing B-400045-2
    Carrier terminal panel, drawing
    22
    B-400044-2 Distances, operating (table TIT)................17
    Dimensions:
    Packed (table TV).......................... 26
    Unpacked ............’.......................2
    Directional filters:
    DF (fig. 80)...........................816,85c
    E DF (fig. 80)..........................5a,	88a
    W DF (fig. 90)..........................5a,	88a
    20
    Electrical characteristics (table I).............7
    Equalization ...................................1c
    Extensions :
    Check of—
    Four-wire ............................94c
    Two-wire ............................94ft
    To voice-frequency carrier telegraph systems (fig. 22).........................24
    To voice-frequency telephone repeater and other carrier telephone systems (fig. 21) ..............................  23
    Two-wire and four-wire......................22
    Filters:
    Band-pass filter BF.......................85ft
    Characteristics (table XVI)...............106c
    Directional filter DF......................85c
    Directional filters E DF and	W DF....5a, 88a
    Line filter LF..........................6a,	90a
    Low-pass filter LP.........................85a
    Procedure for locating trouble.............106
    Transmission characteristics of terminal filters (figs. 78 to 80)..................85
    FITCAL. (See Preventive maintenance.)
    Frequency range ................................7a
    Fungiproofing. (See Moistureproofing and f ungiproofing.)
    28 2
    95,97 6,104
    6, 104
    10
    1
    113 113
    27
    26
    25
    97
    124
    97
    6,104
    10,108
    97
    123
    Carrier Repeater OA-IO/FC (figs. 89 to 91)............................88
    Transmission performance requirements (fig. 92).............89
    Carrier Terminal OA-13/FC (fig. 75)..78
    Directional filter ...............816
    Hybrid coil ......................81a
    Jacks .............................81	d
    Oscillator .......................81c
    Power supply (fig. 76).............82
    Radio link operation...............84
    Receiving circuit .................80
    Switches (figs. 83 to 88)..........87
    Termination, four-wire (fig. 77)....83
    Transmission characteristics of filters .........................85
    Band-pass BF (fig. 79).......856
    Directional DF (fig. 80).....85c
    Low-pass LP (fig. 78)........85a
    Transmission performance, terminal (table XII) (figs. 81 and 82) .......................  86
    Transmitting circuit ..............79
    General:
    Carrier Filter F-36/FC (line panel).....6
    Carrier Repeater OA-IO/FC (fig. 10)....5
    Carrier Terminal OA-13/FC...............4
    Four-wire (fig. 7).................4c
    Radio link (figs. 8 and 9).........4d
    Two-wire (fig. 6)................4a,	6
    Gain:
    Adjustments (tables V and VI)..............36
    Gain-frequency characteristics:
    Repeater (fig. 92)....................89a
    Terminal (figs. 81 and 82)............86c
    Limitations on use of gain :
    Repeater .............................89a
    Terminal .............................866
    Limitations (singing) ....................17d
    Loop gain measurement......................54
    Maximum gain, repeater....................89a
    Maximum permissible transmitting gain....22c
    Maximum transmitting and receiving gains, terminal (table XII).............86a
    Repeater .................................17c
    Terminal .................................176
    93
    107
    108
    108
    110
    110
    110
    104
    107
    93
    95
    95
    96
    95
    96
    97
    94
    100
    96
    97
    97
    97
    97
    97
    94
    10
    6
    4
    6
    6
    4
    39
    107
    100
    107
    100
    21
    67
    107
    26
    97
    21
    20
    Gain controls:
    97	E-W and W-E GAIN......................5a, 886	6,104
    Procedure for locating trouble............107a	124
    10	REC GAIN ..............................17,80a	20,94
    TR GAIN ..................................79d	94
    Ground connections ............................30	35
    135
    Paragraph Page
    Grounding shielded wire........................37b	40
    Hybrid coil .............................17e, 22b, 21,25,
    81a	95
    Identification of wires.......................37 a	40
    Impedance
    Intermediate and entrance cables (fig. 17). ,15a	19
    Low- and high-pass filters.................90a	108
    Open-wire lines ...........................14&	19
    Radio equipment ...........................21a	24
    Repeater ..................................896	107
    Terminal ..................................86d	100
    Insertion losses, nonloaded cable (fig. 17)
    Jacks ....................................81d,	107c 96,124
    Lay-out:
    Radio link ................................21	24
    System ....................................12	14
    Limitations, number of repeaters............. ,.lc 1
    Line connections. (See Connections.)
    Line filter:
    Balancing unit LFB.....................6b, 90b	10,110
    Balancing network LF BN................6d, 90b	10, 110
    Low- and high-pass.....................6a, 90a	10,108
    Network LFN .........................  6c,	90a	10,108
    Line-up, system (figs. 54 and 55)...............53	66
    Location of equipment...........................25	28
    Loop gain. (See Gain, terminal and repeater.) Loop gain measurement..........................54	67
    Low-pass filter LP........................79a,	85a	94, 97
    Lubrication ...................................69	80
    Maintenance parts:
    Carrier	Filter F-36/FC..............App.	II	129
    Carrier	Repeater OA-10/FC...........App.	II	129
    Carrier	Terminal OA-13/FC...........App.	II	129
    Modulator .....................................79b	94
    Moistureproofing and fungiproofing: General .......................................70a	80
    Treatment after repairs.....................74	89
    Treatment of:
    Carrier Filter F-36/FC.................73	84
    Carrier Repeater OA-10/FC (figs. 70 to 73)..............................72	84
    Carrier Terminal OA-13/FC (figs.
    63 to 69).............................71	80
    Mounting plate space	requirements..............2	2
    Noise .........................................16,97c	19,117
    Open-wire lines ..................................14	18
    Attenuation (table II).......................14a	18
    Impedance ...................................14&	19
    Operating distance (table III)....................17	20
    Operation under unusual conditions :
    During failure of a repeater..................62	74
    Extreme weather conditions....................60	74
    Other facilities other than open-wire.........61	74
    Oscillator circuit ......................55,	79b, 80c, 68, 94,
    81c, 105 95,123
    Paragraph Page
    Oscillator:
    Frequency adjustment (fig.	105).............110	126
    Output measurement (fig.	49)...............48	62
    OSC transformer fiber tube.................55b,	81c 68,95
    Packing instructions ............................28	31
    Pad R2 ........................................80, 12, 14,
    21a, c, 24 24, 27
    Paragraph Page
    Terminal circuit descriptions, (See Circuit descriptions.)
    Terminal strips ..................................3	2
    Terminating connections. (See connections.) Terminations and	extensions ...................22	25
    Extensions .................................22c	26
    Four-wire ...................................83	96
    Terminations	(fig.	20)................8a,22b	12,25
    To voice-frequency carrier telegraph systems ....................................24	27
    To voice-frequency telephone repeaters and other	carrier telephone systems.....23	26
    Testing equipment (table XIV).................43,92	60,111
    Testing power ..........................7e,	19b, c, 12,23,
    44a, b	60
    Test instrument	requirements..................44c	60
    Tests:
    Outline of detailed tests, adjustments and system line-up..........................45	61
    Channel net loss-frequency (fig. 58)....56	70
    Channel net loss measurement (fig.	62).59	73
    Loop gain measurement....................54	67
    Oscillator output measurement (fig.	49) .48	62
    Receiving gain measurement (table VII, fig. 50)...........................49	62
    Repeater gain measurement (table IX, fig. 53)............................52	65
    Singing .................................98	118
    Transmitting gain measurement (table VIII, fig. 51)...................98	118
    Trouble (table XIII).....................91	110
    Vacuum tube .............................47	62
    Tools and repair equipment......................109	125
    Transfer, carrier circuit. (See Carrier cir-
    cuit transfer.)
    Transmission characteristics:
    Terminal filters (figs. 78 to 80)............85	97
    Directional filter W DF (fig.	90)..........88a	104
    Transmission diagram (fig. 18)...................18	22
    Transmission-frequency characteristics, overall system (table I, fig. 11)..................7b,	10
    Transmission measurement .....................19,44	23,60
    Transmission performance: Repeater .......................................89	107
    Terminal ....................................86	97
    Transmission, poor quality......................97d	117
    Transmission troubles, procedure for localization .........................................97	116
    Transmitting and receiving gains, maximum (table XII) .............................. 86a	97
    Transmitting gain measurement (table VIII, fig. 51) .......................................50	63
    Transmitting output adjustment	(fig. 52).......51	65
    Trouble location: Amplifiers (fig. 103)..........................104	123
    Filters (table XVI, fig. 104)...............106	123
    Jacks .....................................107c	124
    Line panel trouble test.....................102	122
    Localization of system failure: Radio link .................................96	116
    Wire (figs. 96 to 98)....................95	114
    137
    Paragraph Page
    Trouble location—Continued Localization of transmission troubles...........97	116
    Clearing poor quality...................97d	117
    Noise and crosstalk.....................97 c	117
    Noise and power hum.....................97 c	117
    Sectionalization tests: Radio link..............................97b	116
    Wire ..............................97a	116
    Singing ................................97 c	117
    Oscillator .................................105	123
    Preliminary procedures ..................... 94	113
    Check: Four-wire extensions ...................94c	113
    Two-wire extensions and terminations ..........................94&	113
    General steps ..........................94a	113
    Potentiometer .............................107a	124
    Power supply ...............................103	122
    Repeater panel trouble tests	(fig. 101).....101	121
    Check of both directions of transmission ...............................101a	121
    T rouble: Both directions ...................101&	122
    One direction ................101c	122
    Singing .....................................98	118
    Switches ...................................W7b	124
    Technique ...................................91	110
    Terminal panel trouble tests : Wire ........................................99	119
    Check of transmitting and receiving circuits (fig, 99)..........99a	119
    Paragraph Page
    Trouble location—Continued:
    Wire—-Continued:
    Trouble:
    Both transmitting and receiving circuits .............99b	120
    Receiving circuit ............99d	120
    Transmitting circuit .........99c	120
    Radio link ...................100	121
    Test equipment (table XIV).................92	111
    Trouble	tests (table XIII)..............91	110
    Use of diagrams and charts.................93	112
    Unpacking instructions (table IV, figs. 23 to 25) ........................................26	28
    Unsatisfactory Equipment Report (WD AGO Form 468)	(fig. 74).................76	91
    Vacuum tube:
    Checks ....................................33	39
    Test ......................................47	62
    Voltage adjustment. (See adjustments.)
    Voltages, tube socket and power supply:
    Repeater (fig. 102).
    Terminal (fig. 100).
    WD AGO Form 468 (Unsatisfactory Equip-
    ment Report) (fig. 74).
    Weight:
    Packed .................................. 26	28
    Unpacked ................................2	2
    Wiring diagrams, (See diagrams,)
    U. S. GOVERNMENT PRINTING OFFICE; 1S4S—62BI91—TM 120
    CIRCUIT NOTES'	’	~	---- |----------------------------------------------------■— ------------------------ -  ---------------- -----------1
    101 terminals J,*, ANO S on the POWER TRANSFORMER ARE	__	I
    PRimaov taps TOR USE with Different POWER SUPPL*	TR	OUTPUT TRANSF I
    voltages. The NOMINAL voltage FOR Each tap is as	TR	JAN-3I0A	.
    FOLLOWS	_	"	" "	1	11 I
    terminal 2 is not used	1nput TRANsr	ji1........	1	12
    TERMINAL >-HO VOLTS	I	"""	—	-....  ....	■ ■ ..
    TERMINAL 4-i»S VOLTS	___ J “	P
    terminal s uovolts	nz pl.I . --- Z- CAP f	¥—	S IL-	EQPT	LINC	Ref. symbol	Value	Rating
    rtx—sx	ITtrcain T7 K Agy iF“1 -	*gc-GA,N	TRC^ ........................------------------------------------------
    -TOP	soob-Zsteps r H? mc2 sooon b - T1L	\ T5^	3”"”	C1.C10.C11	2.16 mf 200 V
    MOO	mooout	T-ljU c.—V\ Z	t\ Z /	~ oC4	toooi^f
    iOS REMOVE straps ANO CONNECT REQUIRED network wwfn	---------r-i	VARISTOR	C0IL	2q qa	O" ■	\ \	\ X	__ 2-40	10 	—4C	GJ	lU.UUU nW
    o~t. «,..«> 6A1.NC,„S	„E	-----------------------r"3’	=—I-r— >*-', j ,	« '___________________-	___________ L-f------------------------------------------------------------1—I--------------------- J R‘	I \\	\\	-	-	-	C C5	2 mf	200 v
    i’n / I “ Hl !	I	---	.]•—t3~	j;-,;	1 \ i »	=oov
    ye±	।--------h—«	f rtf ”	:	________________________ sws gx.‘s,»?r4	C8’C’	4mf 500 v
    CONOIT.ONS or THEfuNE) SW.TCH	-- I	7	'	I	I	P051T10N	EAST POS.T.ON	^ .t
    104 TW„V£ SWITOCS *RC VIEWED FROM The FRONT OR SHAFT	-----------lg........................■>.	__________ I _________ ____________________________________________________________ |	L OUS
    4,01	!	---------------------------------—,	---- ]-	DEMIN	(1-2)	8.9 ohms
    ----------------------------------------------------------------1	_	-4	- ------------------- 12ohms
    *--------•	C6	~ l - f--------------------------------------------------------------------------------------—*------------------------------------------------------------------------------------------- — ----------------—----* ~ ————— —	(5-6)	12 ohms
    >	INPUT TRANSF ‘	*“	—
    J I---------- 3,000 M MF 6o 7-	|	/_________ I	T^ri	HYB	C1"2)	25.5 ohms
    ! I - "■	। C7 osc	I	(3-4)	15 ohms
    ------------------------------------------------------------------------------------------,	hyb	; ।	J----------------f T™44 JAN'3,0A 2	"1	(S’6)	25.5 ohms zAT r 2-mf---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------,	----------4-*---------i--2 L	...................ch-u-o-, A-:	c	~ ~1	<7‘8)	15 ohms
    ±—'LJ------------r-l—,------------------3 I L—__________________________________ w	t~I R7 j—C ”	□ L	-1	MOD OUT	(1-2)	8.4 ohms
    I. I roPT "* ^==z^.oi l3o-GTin—L^w> ±	________ Ci C2 soo*	P_p> U^’ I imeg 5 NZ/XX	i	'	_	(3-4)	19.5 ohms
    i- I	o. fk,’	:—r-----------■7—r-w—।-------------------------------------------------1—_L________J« ■	4 • >-—	----------r'F--------------------------------------------------- "Aid	<5-6> iw ohms
    "*Tr53Sf.5-	1 %s L	-- 1 I If cLS4 ■ _____________I	U-	T_____________________	W'yJ ‘	"•	I-'	“-ZZ'tl --------------------	D	1.45 ohms
    TT	oobpao	6o ' O I	2'6MF „P~Z aieMF	------ '	line '00 rtf O< »*	LINE 0 □ X ’	LINE '°° R rt )) °	C>-u-<0	P	d’2)	44 ohms
    2 ft > -	_______° I	I	CIO 103 CII	r 1	! 'FRONT	1	2front	Zx •	5	seeRnote	o1	(3-4) 44ohms
    R-*»t Frt	f-AVv—-----------------1	I	CIO	---Ol__________________________________________ p_A_ »_ ._P	SEE NOTE 9° r V p s §	rtk	1	F	1	r	—;;------: 7—	,	.*‘ *3	(2-4)	212 ohms
    I	.	U"„’0M	!	_vWk—________________________________ y vH-ll4 W	r-M * :	rW :	;-----“	w	s.oooohms %w
    L5	—X	I .» 2,,"t	\ Z’ J,1____________.J l\ ““	.,	[__s_____LJ	R4> R51R10	S.oooohms ytv
    p_ a> .	i	L:; p’ jc»	Vr-Jfs	•• . -	, •.	’“.r-	.. w !	...	R6	650 ohms
    R	V	I	1	'T' 4MF ±4MF	102	J’O-LONG PUJG	1	---- ----------- 7.	‘	---Q-----TO GROUND	R7 RH	1 meCT	iZ w
    _	Vaukthd	tnah	n	i	I	l"-*"""""....	U	j	av/j ivxa	1 mug	2 »V
    *L1t2Sc»n^Fk	50 ikkV°5 * P * I REC out	_____ P2	y	~"1	/^Fx I	CI	R8	500 ohms 54 W
    MW,rt0	—Ngre 104_____Li7 I	<	output	-j------J___________________________r	P--------------------------- Lzk ' 2 X ■■   n rr-— _________________________________________________________________________________________/ 12 I	R9	1,000 ohms 54 w
    ruu, T	L~~l--------	-I	7Nsr	c>-------------------------- p 3 \line I J.. J /"	3) l'ne	FC'* o 4^K--J	R12	600 ohms 54 w
    ----LJ--------t-----------------------------------------___________R •; a	1—---------- — -------------------------------------------------^-^7............................................ rrj'o o 40 BeTnote ’ j i~ r4l10 °	40 «v5ot£	\>K Jl>-uJT“T'0
    H	—+x	n	Rft)	Jz	OSC	(1-6)	5.9 ohms
    ,1 p‘*c §5^1	eqpt^H o4p p I 77 5'°^ZTT"	---^777-T- ^_^2,r°R	i0^ pt	( II L	L-/ L..U-O	uNE^-f-^	(7-8) 51ohms
    s TT	90 z 05	7 R’ 2-t	--- fk I partof	.T- :-:-=fc=z:=dLJ	1/ pF^	s'-01t	—	IN (pri) 1-600ohmsz*
    o--------V.	_____________________________ —	4	'■00°:	1	> K8	Illi	*£	J6'nil	----------- ---------LP.t_-------------------1—------------------ -q------------------------------------------—	REC OUT	(1-2)	17 ohms
    1 R	-----------------------------------------“J------Z.-AJ2—	.....	\ t,_J >2	.0 Pkf	__________4q<:>	tF -P-” ~L-	-P-. VP1-------------------------------------------------------------------------------(3-4)	13.4 ohms
    p L	TUS°~1 5 6	_____t_J £a_______________J	I’	4	4'	(7-8)	835 ohms
    LMJ	3 ,W	: P^F-	RECfoGtA,N	b-400^4u--------------zshects.sheet. , T	<9-10)	88 ohms
    __________		---	—__	__---[•—»-p	I? 4,iso~-T6>oo~--------------------------------------------------sodbih2DBSUPS	1R 1-^	(1-2)	25.2 ohms ■	“-—_-_-—__J	•—U. Jo - o-		PACKAGED EQUIPMENT	^‘4?	4tl?? ^ms
    mote =j:is symbol for FiAco_LAPiACiroR	---------- ------------------------------------------------------------- TYPE H CARRIER. TELEPHONE	1R xJg 1	(1-2)	4.4 ohms
    ------------------------------------------------------ UNIVERSAL TERMINAL	(3-4)	11.6 ohms
    r	mmmmb mmmb ■■pHMai	FOR T wO*wi RE AND FOuR’WiRE On	/ _A\	9Q/t V|
    < >u-R- . ( Xv<* > ( >u< • <	>t>< J . >1/4- .	DROP SiDL AND W!RE-TO-RADiO CONVERSION	P-0?	OOmS
    *	......	Online StOC,USING mOiSTuRE RESISTANT	--------------——----
    <>B5 eat> os? oaa oai OB4 obi oe>2-	&B9 QBiooBu Obi2	Ar* «.Lt temperaHjRE Ra'^CC apparatus	* Impedance.
    . I II I 1 I I 111/	I	B-400044-1
    CONNECT TO Similarly numbered TERMINALS ON OTHER CaRR'ER TERMINAL	IlS'J'Q
    SEE FIGS IOS 1 106
    Drawing B-400044-1, Sheet 1. Type H carrier telephone terminal, schematic diagram.
    FIG. 101 UNt SWITCH ON WIRE CAST —  g g — FILTER ' ■ 1 X — —■■	FILTER
    0-3,000'1/ X. Z	4JS0-6,900*\/	*	4,150-6,900rV
    FIG. 102 LINE SWITCH ON WIRE WEST EOPT SWITCH ON 2W _________	SEE NOTE 104
    LP Z X. Jt. BF Z	OF
    .... I------------------------ F»-TE" --------C MOO y--------SB------ FILTER -------X------ ««« >------ FILTER
    O-J.OOO'V X /	’	4,150-6,900^	/ AMPLRy^ 4,150-6,9000/
    *-*«£-------	t—TO LINE FILTER
    7.600	I--1	~	»— ■	4	r 1
    *■---- I —0^40%
    TO 4W	----------- ----------------------------1-----
    V-F-tOwP’	 _____	T ' TQ
    OEM	X^BCUF.	_LP	/ x. <9 6	BF	Z	OF
    out	Xamplr- — filter	——< oem y—| B — filter —..................... "	t —.... filter
    0-3,000*3/ x. Z	4,150-6,9000/	/'	4,150-6,90OX.
    FIG. 104 LINE SWITCH ON WIRE EAST EOPT SWITCH ON 4W TLO ___________ SEE NOTE 104
    “n° "........................    O	- FlLTER --------XmOO I j--------------- filter -------Y------	FILTER
    0-3,000%	Xu /X	7,400-10^50%	/	.7^	7,400-10,150%
    TO 4W	*	----T-----
    V-F EQUIP	_____	 f- “TO LINE FILTER
    DEM ■»	/XZRCV0	7	^X.	Jr	OF
    out 1	\amplr----- filter	■——< dem >	3 e——■	filter -----■—— / -■■■■........... filter
    0-3,000%	X 7	4,150-6,900%	/	4.150-6.900%
    FIG. 105
    SEE NOTE 104
    I /X	f	I	X.	|LINE SWITCH ON
    LP	7	\	BF	1/ ^X	nF	RADIO-TRANS. EOPT
    __n~~~------------------------—--------F1LTER IL/--------------------	ALTER S’*'™™**
    0-3,000% Xu y7	\l 4,150-6,900%	7,400-10,150%
    v-pTeow MYBRI° reos	 A  A	| TO LINE filter
    |““—I- FILTER J 1----------------------P------------- FILTER
    Lws	0-5.000x>	x. 7	* '	7,690-IOjaOA/	/	A.iSD-B^OOO.
    V	U——--------------------------------------------- PACKAGED EQUIPMENT
    TYPE H CARRIER TELEPHONE UNIVERSAL TERMINAL
    B-400044-! nun
    •MEET t ISSUE 3A
    Drawing B-400044-1. Sheet 2. Type H carrier telephone terminal, schematic diagram.
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    #	<3	P4U--	p t u— — p4 • — n	— -Pau— -Pau	®® x. “51_p2J	__--------—p	p*
    a	______J]_____"I gj ______________g|g2________2 J S 2_s_____g 3_____? J p S__2 S	~ p 8*£~R“* 2~P d S S 9JB 3 5 R________________________3______*J 4d--a--------21_r
    S ®
    ,------ LINE FILT ---,------------ 4W RtC. ------------------- 4WTR ______---------------- wop -------_
    66 wb 67 fN 66	69 Ri 70 R1 71 Rn 73	75 Io
    A* 0IR F'lT LINC 1 U	4-------DEU 0UT —I-Is	4-------M0° IM “T__ “V	/4-----2* HT0 —I--V-\	- o de^,to® ■	—1—~
    ' ' —————{	---- P	.	----- P —	----- P2 - - —
    ?“	0“	S	C0	f J	« £	“ i ► 4 O “	«
    -----Pau---5>	£>	Ai	------- p---------p----A*	?
    r> ©	in xi	O w,	oO	«.	—	njM	r^<0	x>  «D
    _________________________________«q| ”|________S g|__________§ £|	5®	5 ®	tjc	5®	o®	J; <1	______	OIR FR-	BF	r-7TX, L?CO	93 R>l 02 Q3 Q4 05 QB Q? 	60 50	FILTER	5 6
    s i-----------------r-------z^nductop -------r	-------J	L q qI	I? < ?-r
    ------1-1-w...............3’coro	\	\ pt । pj |	■*- pjjj ■*- SxipauPau ^cau Tau -----------	g—    ........ ■	. a - ,,	\	8,000 ORES I -	------------------------------------------ — ~PA°	V PT 1	|
    “	O	« t i £	Y	“.YoYaY>i“L-
    ■ 4	ittm	“ d > 4 o	« O “	> m ®
    tM	p-~* —	-b—- — p -—r~H
    2	Uh iD
    NOTES
    I. WIRES NOT OTHERWISE DESIGNATED ARE 22 GA-
    3 LEADS DESIGNATED ”U' ARE 22CA SHIELDED WiM
    4. C—>.— DENOTES SHIELD CONNECTION.
    6. “KI" DENOTES TOP OR LEFT TERM. ON STRIP
    7. “ P“,“ Pl”. “P2“. a. "P3“ DENOTE PAIR
    3. “ PT" DENOTES LEADS FURNISHED AS PART OF APPARATUS.
    9. -«— DENOTES SPLICE-
    (I. ON PWR TRANSFORMER RECONNECT LEAD OH TERM 7 TO TERM B» AND RECONNECT LEAD ON TERM- 5 TO TERM 4 OR 3 AS REQUIRED.
    »**o44-a
    ISSUE SA
    TYPE H CARRIER TELEPHONE TERMINAL PANEL WIRING DIAGRAM
    0-400044-2
    Drawing B-400044-2. Type H carrier telephone terminal, wiring diagram.

    FIG. I	---
    01
    W-E IN	I	W-E.	,,,, JL-. W-E OUT
    __________________NPUT TRANSF	L^«*5\3 JAN-3I0A..IMF—C4 OUTPUT TRANSt .......................................................  - —ct	30-—x_«2L3:r-¥--—	1 *'* p—t——-—
    | W-eCAIN	I ■[	?	xwnl	——LOW CROUP
    pot	it <	.i-*.... ng	SRI jig
    »	50 06	। aS?	Ax„	1 777 r
    ’ bob-steps	III	S650ft	I
    JL —5--------------il U------- ca --------1 " ■■■■ ....—I .. 5 jk—L—
    ■---- hH	«—--------------------1
    10,000 ■■—— '■'	-—	MMF
    A5	A4 4
    ihtrtVHrnr4...	... TTrrtMrTrii
    “rfi p u P A LINE DIR ' 1 J. directional	directional I I i DIR LINE A p u Al
    I •	' I V FILT c^-q FILT Y ? Y	™-TER	---------- ’"“j	p|LTER	? 7 Y FILT FILT U ] Y | c’
    ^..Ul g.m_4	['1. ■ In	J4I 18djji
    2® IsT	R	E-WOLJT 4='“r A-*CA!	E-W IN	R	1-4—I 55
    JJ ■—OUTPUT	a	INPUT TRANS*	u
    r-F At-4 -----------------------------------------
    L 1 isi |®A	‘ — flj | e.„o»K j -------------------------------/—
    ____________LI I, I T kll 1	1_____________
    R5 I	____। ~s.ZJL,_________
    ’MEC|---------ZJ	PWR	---------------------------
    5	TRANSF
    R4	C5	I	I—■■■...—■ I.    m——...........— ■■■■■■I O 5 SEE NOTE
    NOTE. 4 IS SYMBOL FOR FIXED CAPACITOR	----------1—|f-----*—	•	J	101	^ZoOMS-i---------'--ISs’uE 4a' '
    ESO A	iqCOOMMf	---------i o-TAr—--------—---------W	T I POLARIZED
    J,	c< osn	Zo ...... o g-03	J^PLUG
    CIRCUIT NOTES’	p	WrIsTOR 56. I cl ■*
    101. TERMINALS 3.4,1 S ON POWER TRANSFORMER ARC	*?"?3	lZ *>>3 ' ' ’fa	V?7	PACKAGED EQUIPMENT
    PRIMART TAPS FOR USE WITH DIFFERENT POWER	I, F Ur *	I	I P I?	I
    supply voltages as follows.	■	—-----------A >4 । I i -----------i	TYPE H CARRIER TELEPHONE
    TERM. 3-110 VOLTS	TERM. 2 IS NOT USED	440440	1 03 ?ft >M I I ® 1	OCDCJTCO
    TERM. 4-IISVOLTS	c.	c, I...	| j SEE Li6GA 2 C0N-	REPEATER
    J^Kec’t-'t^Wm’.NAL HAVING DESIGNATED	A 4Mr	A 4MT pARISTORyi------'note 102	DUCTOR, 3’CORD	Ts^MDftT^
    VOLTAGE NEAREST TO THE MEAN ONE VOLTAGE.	T	P
    102. TERMINAL 8 ON THE POWER TRANSFORMER IS	I
    AN AGING TAP WHICH IS CONNECTED TO THE	- t ----- --- - t .	■	AfiAAt
    RECTIFIER IN PLACE OF TERMINAL 7 WHEN THE	<1	6	.... ' ..	O *rWV*t J I
    RECTIFIER HAS AGED SUFFICIENT^ TO R6QUIR8	-O	.................** * ""»>
    ADWTKJNAt APPME& VOLTAGE.	X	Tt»uc»
    Ref. symbol	Value	Rating
    Capacitors
    Cl, C2	4 mf	500 v
    C3, C5	10,000 mmf	400 v
    C4	1 mf	200 v
    C6 Coil	1 mf	800 v
    P Resistors	(1-2)	44 ohms (3-4)	44 ohms	• •
    Rl, R3	5,000 ohms	% w
    R2, R4	650 ohms	J4 w
    R5	1 meg	% w
    R6 Transformers	0,5 ohm	% w
    E-W IN	(1-2)	25.2 ohms	a
    W-E IN	(3-4)	4,190 ohms
    E-W OUT	(1-2)	4.4 ohms
    E-W OUT	(3-4)	11.6 ohms (5-6)	284 ohms
    Drawing B-400045-1. Type H carrier telephone repeater, schematic diagram.
    b! Ol	m	o	&	to]	m	u>| ml	tr>	4		CM	CM	W CM
    o	<9	tc ?	CORD—_> “	*	<9	0
    >- >-	£ K	as i~ >.	“mm	----PT " — t	10	>- > i x
    PBU—*—*	P	--— P	— —p ।--------------.1	P6U —*4*~P
    4 C-:>;	g	CAPfS £-----------*-|R4 RES 650X1^- -—[	< —n
    । 	ft o	o cr > ►	> >
    CORD--«»
    RS	 I	Q A—-p	LINE	Q A—to	CAPACITOR	18 S~R !( j %
    Of	/	tfrm	XX X/	f	(	T ?
    -------------------------P&U -----7,	AaF- NEAREST-J8'4y\	A-------pau--------A----------------	u— -o
    ____________Pau_____;_'.1^ I L p p	KN0B '~TJ 1	-----------------PaU------------“X *	6,38 2—-----to —TERM. STRIP f •>____________________________________________________________________________________________________________________________<. >-J	—~_p	-—p	C->-C.--J	49_BK-_A2—GNO TERM.
    . «■	ooV’rn??	6
    ??	>. >. (t i	a cr >	> a:	>a	o:
    &	 O - DENOTES SHIELDED CONNECTION
    ° *	OI	33	63 64 05 O6l	I—------ / O X	------- XR (46 3°---------8	7. -X- DENOTES SPLICE
    PI	P2	w-E OUT	°° (8 3 8\,	QO w-E IN	10. ON POWER TRANSFORMER DISCONNECT LEAD FROM
    20-- L------02	I t I JAN-3I0A	input TRANSF	TERM.7 AND RECONNECT TO TERM.8 AND OISCON*
    VARISTOR	VARISTOR	OUTPUT TRANSF	\ o’ 6	VT IN	7	,	NECT LEAD FROM TERM. 5 ANO RECONNECT TO
    V	p3	10 2 0	|-l	।----PT----1 \Y o J/ V-T SO.	O2 0S|	TERM. 3 OR 4 AS REQUIRED
    ---* '---------z	L _ _ — _ I I R2 RES |_1____________I
    t 650 A
    , f	P ——*
    »	-	!	t	>	£
    ? ?	5I4 THIS DRAWING , TZ TT I . I .
    t	.	-		AGREES WITH 1	2	3	4	5
    ^1	CO CD	CXI cm CM	_	-----
    -I ol	 IO	O if	J	to	{ I I I _______ I
    o
    	co______________________________________VL SI30T
    Drawing B-400045-2. Type H carrier telephone repeater, wiring diagram.
    FIGI	HG.4
    LINE FILTER	BALANCING NETWORK
    fi	FOR SIDE CIRCUIT
    -------------*	O	VOICE-FREQUENCY TP REPEATER T-------------------------------------------------------------------TO BALANCE LF B
    ft _ A3_____	7X I .__________________Al T>	r-T 8-9	NETWORK g,,
    TO TYPE H ’■ Q' T Y '	LF HP »—“ 1	।	9—*-	I- O .	,	■	1T" O""
    CARRREPTROR I I !	1	TO LINE	UU-M p	TO V-F TP REPTR LINE
    -.terminal- u py PRZSZ:	section	p -	TOv-flP.	ao/in*. isa±i% [	- ano cx bal net. or to
    s.—J—5La|	; Ri. | y
    ®2 T>	TYPE H CARRIER TELEPHONE
    —o——---------------o lFB *-----------1	LINE FILTER AND BALANCING NETWORK PANEL
    USING MOISTURE-RESISTANT AND WIDE ROTG*eo%°OR0F	P	N	P	_ To L1NE	TEMPERATURE RANGE APPARATUS
    J?a8co®'LO '	।	|	EOU"’
    B-400046-1 ...L—— 1	£---------L—
    Ref. symbol	Value	Rating
    Network LF B	8.5 ohms*
    Resistors PH LF BN	15 ohms	5 w
    LF BN	15 ohms,	5 w
    30 ohms * Effective resistance. Drawing B-400046-1. Type H carrier telephone line panel, schematic diagram.
    FIG. 1	in K.
    IU /*'	NOTES1
    ________--------------------------------------TK1— —r————i	p	(.WIRES NOT OTHERWISE DESIGNATED 82 M
    9°®®	e- 2. ° «	-----4-------—DENOTES SHIELD CONNECTION.
    1 PR W	_________ 2 8L 1	5
    2 IA	J "51	VARISTOR	8	2516 )	----------j--o
    4 3 2 1	 tc. a	~	«	TERM. STRIP
    PANEL GNO TERM.	5	 FIG. 4	5'.	____________________
    co co co	<£>	**	p	r-—।	... ii ■■ ■■■ ■<■■■■ rTT^
    -------------—--------------------------------------9	THIS 0RAW1NS issue 1234 	O	AGREES WITH	' £ ’	j
    S-R IQ	------------------------------*■-
    FIG 2	FIG.3	“ B"	I G u	B-400046-.	[l|2|3|3| | | | |
    KI	O---------------1------T----O
    P r—yA	p F~1	_ RES	[6~T| 1S'W O	8-400046-2	ISSUE 4A
    _______I_______!---o'	——---1----o	p 	 v-G I 2	9L-R |	4	term 8_TYPE H CARRIER TELEPHONE
    “	H.6	3	BR	1	C r R ' TERMSTR,F LINE FILTER a BALANCING
    !±-------r-^	br-r f "o	G-5 Sr« M	network panel
    !--------1—	(------------a_|—Lo ---------------------------------WR(NG 01AGRAM
    f!	|A Hl P V Io ..........................."1-,	|------B-400046-2
    4 5LFN '	TERM. STRIP 4	'	TERM.STR.P	8N	I |Q.R
    filter	network	n	r u t
    ---------- ------------------------------ *-12----------------------------- e p I—
    TER“' TERM. STRIP	thoo.
    Drawing B-400046-2. Type H carrier telephone line panel, wiring diagram.

    num n.n'il Ll.B.?.Af?^S DENTON TX 79203
    Biiiiiiniiiii
    1001896167