    [Installation of Radio and Interphone Equipment in Medium Tank M4 Series]
    [From the U.S. Government Publishing Office, www.gpo.gov]

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    jvi WAR DEPARTMENT TECHNICAL MANUAL
    NON-CIRCULATING
    INSTALLATION OF RADIO
    AND INTERPHONE EQUIPMENT
    IN MEDIUM TANK M4 SERIES
    «:/A‘ DEPARTMENT ■	20 APRIL 1944
    NTSU LIBRARY
    W A R DEPARTMENT TECHNICAL MANUAL
    TM 11-2704
    INSTALLATION OF RADIO
    AND INTERPHONE EQUIPMENT
    IN MEDIUM TANK M4 SERIES
    W A R DEPARTMENT	•	2 0 APRIL 1944
    United States Government Printing Office Washington : 1944
    For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 10 cents
    WAR DEPARTMENT, Washington 25, D. C., 20 April 1944.
    TM 11-2704, Installation of Radio and Interphone Equipment in Medium Tank M4 Series, is published for the information and guidance of all concerned.
    [A. G. 300.7 (14 Mar 44).]
    By order of the Secretary of War :
    G. C. MARSHALL,
    Chief of Staff. Official :
    J. A. ULIO,
    Major General,
    The Adjutant General.
    Distribution :
    As prescribed in paragraph 9 a, FM 21-6: Armies (10); Corps (10); Sv C (10); Depts (10); Def Comds (2); D (2); B (2);IC 6, 11, 17 (5).
    IC: T/O & E 6-166, Hq Hq Btry Armd FA Bn.
    IC 11: T/O & E 11-107, Sig Dep Co; 11-127, Sig Rep Co; 11-327, Sig Port Sv Co.
    IC 17: T/O & E 17-14, Maint Co, Armd Regt; 17-26, Hq Hq Co Tk Bn; 17-27, Medium Tk Co, Armd Regt; 17-46S, Hq Hq Co Medium Tk Bn Sp; 17-47S, Medium Tk Co, Medium Tk Bn Sp.
    For explanation of symbols see FM 21-6.
    II
    CONTENTS
    SECTION I. GUIDE TO USE OF THIS MANUAL.	PvJe
    Purpose_______________________________________________________________________ 1	1
    Equipment_____________________________________________________________________ 2	1
    Symbol (&)____________________________________________________________________ 3	1
    Holes and brackets____________________________________________________________ 4	1
    •	Before beginning installation_____________________________________________ 5	1
    Immediately after installation_______________________________________:____ 6	1
    II.	RADIO SET SCR-508—(&).
    Required parts____________________________________________________________ 7	2
    Assembly and installation_________________________________________________ 8	2
    III.	RADIO SET SCR-528-C&). Required parts-------------------------------------------------------------------- 9	4
    Assembly and installation____________________________________________________ 10	4
    IV.	RADIO SET SCR-538—(&).
    Required parts_______________________________________________________________ 11	6
    Assembly and installation---------------------------------------------------- 12	6
    V.	INTERPHONE EQUIPMENT FOR RADIO SETS SCR-508-(&), SCR-528-(&), and SCR—538-(&).
    Required parts--------------------------------------------------------------- 13	8
    Assembly and installation____________________________________________________ 14	8
    APPENDIX.	IGNITION NOISE SUPPRESSION	IN MEDIUM TANK M4 SERIES__________________ 1-2	22
    III
    INSTRUCTION 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, or other heavy tools.
    2.	Cut—Use axes, handaxes, or machetes.
    3.	Burn—Use gasoline, kerosene, oil, flame throwers, or incendiary grenades.
    4.	Explosives—Use firearms, grenades, or TNT.
    5.	Disposal—Bury in slit trenches, fox holes, or other holes. Throw in streams. Scatter.
    USE ANYTHING IMMEDIATELY AVAILABLE FOR DESTRUCTION OF THIS EQUIPMENT
    WHAT—1. Smash—All vacuum tubes, crystals, control dials, coupling coils, transformers, speakers in the receivers, external loudspeakers, microphones, headsets, dynamotors, and cable connectors.
    2.	Cut—All connecting wires, cording, and cabling.
    3.	Burn—All equipment, and all associated training, technical, and installation manuals.
    4.	Burn or scatter—All remains, after destroying their usefulness.
    IV
    DESTROY EVERYTHING
    SAFETY NOTICE
    This equipment uses high voltages which are dangerous to life. Observe all safety precautions. Make no adjustments inside the equipment with the power switch on. Do not operate the equipment with the shields removed. Do not connect power to any unit of the radio set until operating instructions have been read completely.
    V
    SECTION I
    GUIDE TO USE OF THIS MANUAL
    1.	Purpose.
    This manual provides methods and procedures, based upon actual field experience, for installation of radio and interphone equipment in Medium Tank M4 series. Items required to make a complete operating installation are listed for each radio set and interphone equipment.
    2.	Equipment.
    Installations covered include the following radio sets:
    SCR-508-(&) SCR-528-(&) SCR-538-(&)
    3.	Symbol (&).
    The symbol (&), used throughout this manual, refers to all existing 24-volt models of radio sets and interphone equipment mentioned, and to all models of other items of equipment with which it appears.
    4.	Holes and Brackets.
    Holes and brackets required for installations of the radio sets or interphone equipment normally are located prior to delivery of Medium Tank M4 series. Drilling instructions will be given in the pertinent section of this manual for any other necessary holes and brackets. Holes and brackets
    in the vehicle or on any radio or interphone part should not be relocated unless absolutely necessary.
    5.	Before Beginning Installation.
    Illustrations, installation methods, and any subsequent changes to this manual must be studied carefully before an installation is made.
    CAUTION: Medium Tank M4 series has a 24-volt electrical system. Before installing any radio set or interphone equipment covered in this manual, be sure that it is designed for a 24-volt installation, and that 24-volt dynamotors have been supplied.
    6.	Immediately After Installation.
    At the completion of the installation, a thorough operating check must be made to determine that the equipment has been properly installed and is in working order.
    CAUTION: Do not operate any of the radio or interphone equipment until the instruction book or Technical Manual covering the specific radio set or interphone equipment has been studied carefully. Otherwise, damage to the equipment may result.
    1
    SECTION II
    RADIO SET SCR-508-(&)
    7.	Required Parts.
    Items necessary for installation of Radio Set SCR-508-(&) in Medium Tank M4 series are listed below.
    Quantity	Stock No.	Item
    1 .		2A262		Antenna A-62 (Phantom).
    1«		3E1307A-5.5		Cord CD-307-A, 65 ins. long, for Headset HS-30-(&).
    1 a		3E1604		Cord CD-604, 6 ins. long, for Headset HS-30-(&).
    1		2Z2651-423		Clamp MC-423, for securing Mast Sections MS-51 and MS-52.
    1		2Z2651-424		Clamp MC-424, for securing Mast Sections MS-52 and MS-53.
    1		6Z3147		Connector No. 61007 and Bondnut BL-50, Appleton Electric Co.
    1		2Z3400-108		Cover BG-108, for Mast Base MP-48.
    2b		3H1636(&)		Dynamotor DM-36-(&), 24 volt, including attached spare parts.
    1 b		3H1637(&)		Dynamotor DM-37-(&), 24 volt, including attached spare parts.
    1		6L50-508V8		Hardware bag.
    1 “		2B830(&)		Headset HS-30-(&).
    1		2A2088-48		Mast Base MP-48, or Mast Base MP-48-A.
    1		2A2351 		Mast Section MS-51.
    1		2A2352		Mast Section MS-52.
    1		2A2353		Mast Section MS-53.
    1 c		2B1617(&)		Microphone T-17-(&).
    1		2Z6721-237(&)		Mounting FT-237-(&), including Cord CO-278 to car terminal box,
    		necessary mounting bolts, locknuts, etc.
    2		2C4403(&)		Radio Receiver BC-603-(&), including one set of tubes installed.
    1		2C6494(&)		Radio Transmitter BC-604-(&), including one set of tubes installed and
    	2Z8056(&)		necessary crystals.
    1			Roll BG-56-A, for antenna mast sections.
    5 d ft		1B128		Wire, W-128.
    a Headset HS-18 may be substituted for Headset HS-30-(&) and Cord CD-604.
    b Dynamotor DM-36-(&) and Dynamotor DM-37-(&) may already be installed in Radio Receivers BC-603-(&) and Radio Transmitter BC-604-(&) respectively.
    0 Microphone T-30-(&) and Cord CD-318 may be substituted for Microphone T-17-(&).
    d Not less than 8 feet nor more than 10 feet of coaxial cable may be substituted for Wire W-128. For preparation of coaxial cable see figures 10 and 11.
    8.	Assembly and Installation.
    a.	Components of the radio set should be installed as follows (refer to figs. 5, 6, and 8 for bracket details) :
    Part and location
    Mounting FT-237-(&), including Cord CO-278, on bracket turret bulge.
    Mast Base MP-48, on mast base well, left rear of turret bulge (for Mast Base MP-48-A, see fig. 12).
    Method and materials
    Mount as shown in figure 1. Secure with hardware provided.
    For this installation, Wire W-128, internal, may be used. Cut the wire to proper length and strip one-half inch of insulation from one end.
    2

    Part and location
    Dynamotors DM-36-(&), in cabinets of Radio Receivers BC-603-(&).
    Dynamotor DM-37-(&), in cabinet of Radio Transmitter BC-604-(&).
    Radio Transmitter BC-604-(&), including necessary crystals, on Mounting FT-237-(&).
    Radio Receivers BC-603-(&), on Mounting FT-237-(&).
    Connector No. 61007 and Bondnut BL-50.
    Cover BG-108.
    Headset HS-30-(&).
    Microphone T-17-(&).
    Mast Sections MS-51, MS-52, and MS-53, on Mast Base MP-48.
    Roll BG-56-A.
    b.	CORDING AND WIRING.
    3 and 4. Leave sufficient slack in all motion of the shock mountings.
    nections before installing Cord CO-278 strip in the turret terminal box.
    580744°—44-2
    ...
    Method and materials
    Clean and tin this end and solder tip, item 6B, to it as shown in figure 2. Loosen set screws 8 and 9. Remove assembly 7 and install wire inside mast base through hollow stem, item 1, inserting the metallic tip in the slot as far as possible. Tighten setscrews 8 and 9. Then refer to figure 2, remove items 2, 3, 4, and 5 from mast base, and install mast base through hole in mast base well, as follows: Place item 1 through hole in well, and item 2 over item 1. Tighten in place with item 3. Place item 4 over item 1 and tighten firmly with item 5. Now slip insulator 6C, rubber gasket 6D, and insulator 6E over wire W-128, and install inside hollow stem, item 1. Follow up with gasket, item 17, and retaining collar, item 18. Leave sufficient slack inside the stem to permit flexing of mast base.
    If the dynamotors are not already installed, loosen screw lock in rear center of receiver cabinet, remove the chassis, and bolt the dynamotor unit on top rear of the chassis.
    If the dynamotor is not already installed, loosen two screw locks on front panel of transmitter cabinet and pull out crystal case. Loosen four screw locks holding cover on top of transmitter and remove cover. Bolt dynamotor unit in left rear of transmitter chassis.
    Mount as shown in figure 1. Secure with screw locks.
    Mount as shown in figure 1. Secure with screw locks.
    Install through knock-out hole in terminal box to secure Cord CO-278.
    Place over Mast Base MP—48 when equipment is not in use.
    Use Cords CD—604 and CD—307—A to connect headset to jack in Radio Receiver BC-603-
    (&).
    Plug cord into microphone jack of Radio Transmitter BC-604-(&).
    Screw mast sections together and secure with Clamps MC-423 and MC-424. Mount on mast base and secure Mast Section MS-53 as shown in figure 11. Carry mast sections in Roll BG-56 or BG-56-A when not in use.
    Disposition left to discretion of using arms.
    Cord and wire Radio Set SCR-508-(&) as shown on figures cording and wiring at Mounting FT-237-(&) to permit free To prevent accidental shorts on the battery, complete all other con-connecting Mounting FT-237-(&) and the battery terminal
    3
    SECTION ill
    RADIO SET SCR-528-(&)
    9.	Required Parts.
    Items necessary for installation of Radio Set SCR-528-(&) in Medium Tank M4 series are listed below.
    Quantity	Stock No.	Item
    1		2A262		Antenna A-62 (Phantom). Cord CD-307-A, 65 in. long, for Headset HS-30-(&). Cord CD-604, 6 in. long, for Headset HS—30-(&). Clamp MC-423, for securing Mast Sections MS-51 and MS-52. Clamp MC-424, for securing Mast Sections MS-52 and MS-53. Connector No. 61007 and Bondnut BL-50, Appleton Electric Co. Cover BG-108, for Mast Base MP-48. Dynamotor DM-36-(&), 24 volt, including attached spare parts. Dynamotor DM-37-(&), 24 volt, including attached spare parts. Hardware bag. Headset HS-30-(&). Mast Base MP-48 or MP-48-A. Mast Section MS—51. Mast Section MS-52. Mast Section MS-53. Microphone T-17-(&). Mounting FT-237-(&), including Cord CO-278 to car terminal box, necessary mounting bolts, locknuts, etc. Radio Receiver BC-603-(&), including one set of tubes installed and necessary crystals. Radio Transmitter BC-604-(8), including one set of tubes installed and necessary crystals. Roll BG-56-A, for antenna mast sections. Wire W-128.
    1 “		3E1307A-5.5
    1 a		3E1604
    1 		2Z2651-423
    1		2Z2651-424
    1 		6Z3147
    1		2Z3400-108
    lb		3H1636(&)
    lb		3H1637(&)
    1 •_		6L60-528V8
    1 a		2B830(&)
    1		2A2088-48
    1		2A2351
    1		2A2352
    1		2A2353
    1 o		2B1617(&)
    1		2Z6721-237(&)
    1		2C4403(&)
    1		2C6494(&)
    1		2Z8056(&)
    5 d ft 		1B128.

    “ Headset HS-18 may be substituted for Headset HS-30-(&) and Cord CD-604.
    b Dynamotors DM-36-(&) and DM-37-(&) may already be installed in Radio Receiver BC-603-(&) and Radio Transmitter BC-604— (&) respectively.
    c Microphone T-30-(&) and Cord CD-318 may be substituted for Microphone T-17-(&).
    d Not less than 8 feet nor more than 10 feet of coaxial cable may be substituted for Wire W-128. For preparation of coaxial cable see figures 10 and 11.
    10.	Assembly and Installation.
    a.	Components of the radio set should be installed as follows (refer to figs. 5, 6, and 8 for bracket details) :
    Part and location
    Method and materials
    Mounting FT-237-(&), including Cord CO-278, on bracket inside turret.
    Mast Base MP-48, on mast base well, left rear of turret bulge, (for Mast Base MP-48-A, see fig. 12.)
    Mount as shown in figure 1. Secure mounting with hardware provided.
    For this installation, Wire W-128, internal, may be used. Cut the wire to proper length and strip one-half inch of insulation from one end.
    4
    Part and location
    Dynamotor DM-36-(&), in cabinet of Radio Receiver BC-603-(&).
    Dynamotor DM-37-(&), in cabinet of Radio Transmitter B C-604- (&).
    Radio Transmitter BC-604-(&), including necessary crystals, on Mounting FT-237-(&).
    Radio Receiver BC-603-(&), on Mounting FT-237-(&).
    Connector No. 61007 and Bondnut BL-50.
    Cover BG-108.
    Headset HS-30-(&).
    Microphone T-17-(&).
    Mast Sections MS-51, MS-52, MS-53, on Mast Base MP-48.
    Roll BG-56-A.
    Method and materials
    Clean and tin this end and solder tip, item 6B, to it as shown in figure 2. Loosen setscrews 8 and 9. Remove assembly 7 and install wire inside mast base, through hollow stem, item 1, inserting the metallic tip in the slot as far as possible. Tighten setscrews 8 and 9. Then refer to figure 2, remove items 2, 3, 4, and 5 from mast base, and install mast base through hole in mast base well, as follows: Place item 1 through hole in well, and item 2 over item 1. Tighten in place with item 3. Place item 4 over item 1 and tighten firmly with item 5. Now slip insulator 6C, rubber gasket 6D, and insulator 6E over Wire W-128, and install inside hollow stem, item 1. Follow up with gasket item 17, and retaining collar, item 18. Leave sufficient slack inside the stem to permit flexing of the mast base.
    If the dynamotor is not already installed, loosen screw lock in rear center of receiver cabinet, remove the chassis, and bolt dynamotor unit on top rear of receiver chassis.
    If the dynamotor is not already installed, loosen two screw locks on front panel of transmitter cabinet and pull out crystal case. Loosen four screw locks holding cover on top of transmitter and remove cover. Bolt dynamotor unit in left rear of transmitter chassis.
    Mount as shown in figure 1. Secure with screw locks.
    Mount as shown in figure 1. Secure with screw locks.
    Install through knock-out hole in turret terminal box to secure Cord CO-278.
    Place over Mast Base MP-48 when equipment is not in use.
    Use Cords CD-604 and CD-3O7-A to connect headset to jack in Radio Receiver BC-603-
    (&).
    Plug cord into microphone jack of Radio Transmitter BC-604-(&).
    Screw mast sections together and secure with Clamps MC—423 and MC—424. Mount on mast base and secure Mast Section MS-53 as shown, in figure 11. Carry mast sections in Roll BG-56 or BG-56-A when not in use.
    Disposition left to discretion of using arms.
    b.	CORDING AND WIRING. Cord and wire Radio Set SCR-528-(&) as shown on figures 3 and 4. Leave sufficient slack in all cording and wiring at Mounting FT-237-(&) to permit free motion of the shock mountings. To prevent accidental shorts on the battery, complete all other connections before installing Cord CO-278 connecting Mounting FT-237-(&) and the battery terminal strip in the turret terminal box.
    5
    SECTION IV
    RADIO SET SCR-538-(&)
    11.	Required Paris.
    Items necessary for installation of Radio Set SCR-538-(&) in Medium Tank M4 Series are listed below.
    Quantity	StockfNo.	Item

    a a b a . 	 	 'ft		2A262	 3E1307A-5.5	 3E1604	 2Z2651-423	 2Z2651-424	 6Z3147	 2Z3400-108	 3H1636(&)	 6L50-538V8	 2B830(&)	 2A2088-48	 2A2351	 2A2352	 2A2353	 2Z6721-237(&)	 2C4403(&)	 2Z8056(&)	 1B128		Antenna A-62 (Phantom). Coi'd CD-307-A, 65 in. long, for Headset HS-30-(&). Cord CD-604-(&), 6 in. long, for Headset HS-30-(&). Clamp MC-423 for securing Mast Sections MS-51 and MS-52. Clamp MC-424 for securing Mast Sections MS-52 and MS-53. Connector No. 61007 and Bondnut BL-50, Appleton Electric Co. Cover BG-108, for Mast Base MP—48. Dynamotor DM-36-(&), 24 volt, including attached spare parts. Hardware bag. Headset HS-30-(&). Mast Base MP-48, or MP-48—A. Mast Section MS-51. Mast Section MS—52. Mast Section MS-53. Mounting FT-237-(&), including Cord CO-278 to car terminal box, necessary mounting bolts, locknuts, etc. Radio Receiver BC-603-(&), including one set of tubes installed. Roll BG-56-A, for antenna mast sections. Wire W-128.
    a Headset HS-18 may be substituted for Headset HS-30-(&) and Cord CD-604.
    b Dynamotor DM-36-(&) may already be installed in Radio Receiver BC-603-(&).
    0 Not less than 8 feet nor more than 10 feet of coaxial cable may be substituted for Wire W-128. For preparation of coaxial cable see figures 10 and 11.
    12.	Assembly and Installation.
    a.	Components of the radio set should be installed as follows (refer to figs. 5, 6, and 8 for bracket details) :
    Part and location	Method and materials
    Mounting FT-237-(&), including Cord CO-278, on bracket inside turret.
    Mast Base MP-48, on mast base well, left rear of turret bulge. (For Mast Base MP-48-A, see fig. 12.)
    Mount as shown in figure 1. Secure with screw locks.
    For this installation, Wire W-128, internal, may be used. Cut the wire to proper length and strip one-half inch of insulation from one end. Clean and tin this end and solder tip, item 6B, to it as shown in figure 2. Loosen setscrews 8 and 9. Remove assembly 7 and install wire inside mast base through hollow
    6
    Part and location
    Dynamotor DM-36-(&), in cabinet of Radio Receiver BC-603-(&).
    Radio Receiver BC—603— (&), on Mounting FT-237-(&).
    Connector No. 61007 and Bondnut BL-50.
    Cover BG-108.
    Headset HS-30-(&).
    Mast Sections MS-51, MS-52, and MS-53, on Mast Base MP—48.
    Roll BG-56-A.
    Method and materials
    stem, item 1, inserting the metallic tip in the slot as far as possible. Tighten setscrews 8 and 9. Then refer to figure 2, remove items 2, 3, 4, and 5 from the mast base, and install mast base through hole in mast base well, as follows: Place item 1 through hole in well, and item 2 over item 1. Tighten in place with item 3. Place item 4 over item 1 and tighten firmly with item 5. Now slip insulator 6C, rubber gasket 6D, and insulator 6E over Wire W—128, and install inside hollow stem, item 1. Follow up with gasket, item 17, and retaining collar, item 18. Leave sufficient slack inside the stem to permit flexing of the mast base.
    If the dynamotor is not already installed, loosen screw lock in rear center of receiver cabinet, remove chassis, and bolt dynamotor unit on top rear of chassis.
    Mount as shown in figure 1. Secure with screw locks.
    Install through knock-out hole in turret terminal box to secure Cord CO-278.
    Place over Mast Base MP—48 when equipment is not in use.
    Use Cords CD—604 and CD—307—A to connect headset to jack in Radio Receiver BC-603-(&).
    Screw mast sections together and secure with Clamps MC—423 and MG—424. Mount on mast base and secure as shown in figure 11. Carry mast sections in Roll BG-56 or BG-56-A when not in use.
    Disposition left to discretion of using arms.
    b.	CORDING AND WIRING. Cord and wire Radio Set SCR-538-(&) as shown on figures 3 and 4. Leave sufficient slack in all cording and wiring at Mounting FT-237-(&) to permit free motion of the shock mountings. To prevent accidental shorts of the battery, complete all other connections before installing Cord CO-278 connecting Mounting FT-237-(&) and the battery terminal strip in the turret terminal box.
    580744°—44----3
    7
    SECTION V INTERPHONE EQUIPMENT ASSOCIATED WITH RADIO SETS SCR-508-(&), SCR-528-(&), AND SCR-538-(&)
    13.	Required Parts.
    Items necessary for installation of Interphone Equipment in Medium Tank M4 series are listed below.
    Quantity	Stock No.	Item
    2.'			6Z3147		Connector No. 61007 and Bondnut BL-50, Appleton Electric Co., or equal.
    5		2C1738(&)		Control Box BC-606-(&), including screws, clamps, etc.
    4 a	 5b		3E1307A-5.5		Cord CD-307-A, 65 in. long, for Headset HS-30-(&).
    	3E1318(&). . .		Cord CD-318, control cord for Microphone T-30-(&).
    4 «		3E1604		Cord CD-604, 6 in. long, for Headset HS-30-(&).
    360 ft		3E2213		Cordage CO-213, interconnecting cable.
    1 d		3H1636(&)		Dynamotor DM-36-(&).
    4“		2B830(&)		Headset HS-30-(&).
    1		6L50-508(528)(538)V8. . .	Hardware Bag containing: 11 clamps No. 7.
    1 e		2C1617(&)		Interphone Amplifier BC-605-(&).
    5 b		2B1630(&)		Microphone T-30-(&).
    a Headset HS-18 may be substituted for Headset HS-30-(&) and Cord CD-604.
    b In emergencies, Microphone T-17-(&) may be substituted for Microphone T-30-(&) and Cord CI>-318.
    0 Before cutting Cordage CO-213 and wiring a quantity of interphone equipment, make one check installation of the interphone equipment in Medium Tank M4. Any variation found in lengths of Cordage CO-213 shown on figure 4 connecting the various Interphone Control Boxes BC-606-(&) and Mounting FT-237-(&) may be readily corrected.
    d Dynamotor DM-36-(&) may already be installed in Interphone Amplifier BC-605-(&).
    ' Interphone Amplifier BC-605-(&) is used to provide speech amplification in Radio Set SCR-538-(&). However, it is not required in Radio Sets SCR-508—(&) and SCR-528-(&) where amplification is provided by the speech amplifier section of Radio Transmitter BC-604-(&).
    14.	Assembly and Installation.
    The interphone equipment supplied for Radio Sets SCR-508-(&), SCR-528-(&), and SCR-538-(&) is not completely wired for installation. To interconnect interphone Control Boxes BC-606-(&) as shown on figures 1, 3, and 4, cut Cordage CO-213 to lengths shown on figure 4. At the end of each length, strip back 3/2 inches of outer rubber and 2 inches of shielding. One and one-half inches of shielding will thus be exposed. Slit exposed shielding on opposite sides of the cable and pull back both strips. Slit and pull back one side of the shielding covering the red and green wires. Strip one-half inch of insulation from the black (ground)
    wire close to the end of the outer rubber cable covering. Neatly twist the three strips of shielding together, cut the twisted shielding to proper length, and connect and solder it to the exposed section of the black (ground) wire. Now insert the prepared cable through appropriate hole in Control Box BC-606-(&). Solder ends of wires to numbered studs and clamp the cable. Insert the prepared cable connecting to the radio set through hole on appropriate end of Mounting FT-237-(&) and wire and clamp to terminal board as described above. Follow the same procedure for preparing the cable for connecting Cordage CO-213 to hull terminal box and turret terminal box. Then install components of the interphone equipment as follows:
    8
    Part and location
    Control Box BC—606—(&), for driver, on bracket, center front of hull.
    Control Box BC—606— (&), for co-driver, on bracket, center front of hull.
    Control Box BC-606-(&), for turret gunner, on wall in turret at right side of post.
    Control Box BC—606-(&), for turret leader, in turret, on wall to left of radio.
    Control Box BC—606-(&), for tank commander, on bracket, right side of turret, above gunner’s interphone control box.
    Connector No. 61007 and Bondnut BL-50.
    Dynamotor DM-36-(&), in cabinet of Interphone Amplifier BC-605-(&).
    Interphone Amplifier BC-605-(&), on Mounting FT-237-(&).
    Headset HS-30-(&).
    Microphone T-30-(&).
    Cordage CO-213, for interconnecting interphone components.
    Method and materials
    Mount as shown in figure 1. ware provided.
    Mount as shown in figure 1. ware provided.
    Mount as shown in figure 1. ware provided.
    Mount as shown in figure 1. ware provided.
    Mount as shown in figure 1. ware provided.
    Secure with hard-
    Secure with hard-
    Secure with hard-
    Secure with hard-
    Secure with hard-
    Install through knock-out hole in both the turret terminal box and hull terminal box to secure Cordage CO-213, as shown in figure 4.
    If the dynamotor is not already installed, loosen screw lock in rear center of cabinet and remove chassis. Bolt dynamotor unit on top rear of receiver chassis.
    Mount as shown in figure 1. Secure with screw locks.
    Use Cords CD—604 and CD—307—A to connect headsets to jacks of Control Boxes BC-606-(&).
    To be strapped comfortably around throat above the larynx.
    After mounting and interconnecting control boxes as shown in figure 3, secure cable along walls and hull of tank with clamps, screws, etc., as shown in figure 1. (Refer to fig. 7 for wiring diagram of slip rings and terminal boxes.)
    9
    CONTROL BOX BC*606-(8)(GUNNER)-.	—CORDAGE CO'213
    CONTROL BOX BC-606-(8) (COMMANDER)-r-CLAMP#7	HARDWARE REQUIRED
    \ \	MOUNTING FT-237-(8)i
    ___________________________________________________________________1-------------------1 \	8-5/16"-24X3/4" LONG HEX. HEAD MACH. SCREWS TERMINAL BOX----\\_________________________________________________8-5/16"-LOCKWASHERS.
    CORDAGE ro-PTX__, Z\	JhOOK	1	\	CONTROL BOXES BC-606-(8):
    CORDAGE CO 213	\	X	!	\	12-#8-32 X 5/8“ LONG ROUND HEAD MACH. SCREWS
    A. \	/Z	\	/ I	I	\	!2-#8 LOCKWASHERS .
    / \	\	//	\	'	HOOKS (5 REQ):
    /	-----------yV-------------\--------XZj.---L ------------------ 1	IO-#8-32 X 3/8" LONG ROUND HEAD MACH. SCREWS
    CONTROL BOX BC-6O6-(8)4----//	H0°K XlXxj ZRADK> SET SCR- I	I	CLAMPS8 L0CKWASHERS'
     I'tSwc!-MAST SECTIONS •
    \\	"	MS-51 TO MS-53	<
    H00K\^N“ \ 1 ■ N0TES,
    \‘	/	• FOR WIRING DIAGRAM SEE FIG. 3.
    ^CONTROL BOX BC-606-(&) I /	2. FOR CORDING DIAGRAM SEE FIG. 4.
    (LOADER)	\	3. USE COVER BG-IO8 WHEN MAST SEC-
    ---------- I	|	TIONS ARE NOT INSTALLED.
    “	4. AFTER CUT TO PROPER LENGTH,TIN
    PLAN VIEW	ENDS, FOR CONNECTIONS.
    MAST SECTIONS--\
    MS-51 TO MS-53	\
    MAST BASE MP-48-x 'I
    CORDAGE CO-2I3X	\	I COVER	BG-108—\
    HOOK—i	\	(SEE NOTE 3)	\
    \	---COVER 8G-I08	\
    --------------------------------------------V----(SEE NOTE3)	RECEIVER 6C-603-(8)-\	\ CONTROL BOX BC-606-(a)-1 . I	\	\ lb-----MAST SECTIONS MS-51 TO MS-53
    (COMMANDER)	/	,	- n n \ n	\	\
    /	RECEIVER BC-603-(8) OR-< \	\	/-MAST BASE MP-48
    /	UJ V —1—uuioc w-.oq /ccc notp At	INTERPHONE AMPLIFIER BC-605-(8) \ \	\ /
    ?G°SB0XBC'606’(8’7------------\ I	T^WIRE W 128 (SEE NOTE 4)	TRANSM.TTER BC-604-(8^	\\	|—CORDAGE CO-2,3
    /	J^J^^RD-528(LoCRSC^-&	CORDAGE CO-2.3—x	\-------\	r^™^60" 8G-6°®-<8>
    HOOK-—    ,^<1_____________________________[Ll/jm-z!____	\X i \	\ \ • • Jj X '
    CONTROL BOX BC-606t''T’jk	~	------ ‘	LX2.\
    CLAMP #4x	I	(8) (LOADER)	/ IXaPPLETON CONNECTOR |	\	RADIO SET____'' |------*----hf "'
    I	terminal box-1 j *b^°d°nutbl-50 i	|	^t^np / I .	-------
    I SLIP RING B0X\^	^_..J	SCR-538-(80 °R / JI J	I I Jj-------\--CONNECTION FOR SCR-538-(ft)
    ./( ------------------:--=n------—------------------. ----------4-------------MOUNTING FT-237-(80.. U---------------___________________|
    / V -------"S	:	A	!	!	I TERMINAL BOX —■ [	1
    /'	\	I	j i	I	/	CORDAGE 00-278^^ /\
    /	\	I___________I___l=>________J	■	I	/ '■CORDAGE CO-213 I
    terminal box(-------—-A.	/	1 ;p6pil0e0t70N CONNECTOr7
    APPLETON---\-----------LI	/	I BONDNUT BL-50	,
    CONNECTOR #61007..	/
    BONDNUT BL-50	-------------------------------------------------------------------- '------------------------------------------------------------------>
    TL-10660
    ELEVATION	VIEW A-A	BASED ON
    SC-D-7024-F
    Figure 1. Installation of Radio Set SCR-508-(&}, SCR-528-(&), or SCR-538-{&}, and associated interphone equipment in Medium Tank M4 series.
    10
    11
    I ASSEMBLY	A A QTr.,	AA A „
    n—n	6	(JJ-STEM	QllJ-CAP
    ®A	ASSEMBLY	AA	AA
    x—x 7	(2J-WASHER	(I2J-ADAPTER
    t aa	n—A v
    —----©A	A\	CONNECTION. SECURE	4 > SOLDERING
    7 A	WITH SET SCREW- ©A PLUG
    BASED ON	©A	ITEM (9).
    SC-A-6743-D	TL-IOOI4
    Figure 2. Mast Base MP-48, assembly for installation.
    co 2'3	NOTE:
    ■( >  -----— 2--------------'( y,	/( H-------— -----------------1	I. SHIELD OF CABLE & SHIELD OF TWISTED
    A. Z	Z	I	PAIR OF LEADS IN CABLE SHALL BE SECURELY
    Z//Vl\\	GROUNDED AT EACH END.
    ///I A\\	//JUKKA// I \	zM	2 FOR WIRING OF SLIP RINGS & TERMINAL
    // /	\ \\	/	\	C )'	BOXES SEE FIG. 7.
    / / / I \ \ \	/rhZzOCA	3- ENDS 0F ALL UNUSED WIRES SHALL BE TAPED.
    |l|	ll llllllll l	\X	4. DOTTED CIRCLE AROUND CABLE ENDS
    i J, 5 ; I I *	J J * •> II 5	(SEE NOTE 3)-2—INDICATES SHIELD.
    j g jj S g 3 2	5 g 3 lr 8 3 S	T * &
    -	3 CO CD	CD 5	>■	<3	2 	§oK3°“«o“	INTERPHONE CONTROL BOX BC-60G- <&)	INTERPHONE CONTROL BOX
    (TURRET GUN LOADER I	5 “	m o oo	(TURRET GUNNER I	BC
    rWWdniih	■
    ।----------------------u--1	BASED ON
    TERMINAL STRIP IN MOUNTING FT-237-(&)	SC-D-6992-F	TL-I066I
    Figure 3. Wiring diagram of interphone equipment for Radio Set SCR—508— (<2?), SCR—528—or SCR—538—{&') in Medium Tank M4 series.
    12
    APPLETON CONNECTOR-----
    #61007	___________
    BONO NUT BL-50	4O5O6O+O	NOTE:
    IO2O3O-O	I CORDAGE LENGTHS GIVEN INCLUDE ALLOWANCE FOR MAKING
    rr, o,?	---------- CONNECTIONS IN BOXES AND MOUNTING, AND ARE FOR VEHICLES
    CORDAGE CO 213(10'3 ) ————,-	TERMINAL BOX 	OF CAST OR WELDED CONSTRUCTION.
    2.FOR WIRING DIAGRAM SEE FIG. 3.
    FOR INSTALLATION SEE FIG. I.
    3.ENDS OF WIRE W-128, AFTER BEING CUT TO PROPER LENGTH, SHALL BE TINNED FOR CONNECTIONS.
    4 l-HEADSET HS-30-(S), AND l-MICROPHONE T-30-(8) SHALL BE
    CONNECTED TO EACH CONTROL BOX.
    ^8	Ep	5. USE COVER BG-108 WHEN MAST SECTIONS ARE NOT INSTALLED.
    INTERPHONE CONTROL	[tffl |	INTERPHONE CONTROL
    BOX BC-606-(&)	I"	I	h	BOX BC-606-(a)
    DRIVER	1	]	CO-DRIVER
    LcORDAGE CO-213 (14")
    C1 !l 11	Ln..!,.— ,,.. .... TRANS. RECEIVER INTER. AMPL. 'TRANS.DYN. REC.DYN?
    DYNAMOTOR 11 /	/	BC-604-(8) BC-603-(a) BC-605-(8)	DM-37-(8)	DM-36-(80
    DM-36-(a)--'	RADIO SET SCR-508-(8) I	2	----- I	2
    Y	1 J i|	RADIO SET SCR-528-(a) I	I	----- I	7
    I	RADIO SET SCR-538-(a)	- I	I	----- o TL-10662
    | CONNECTION FOR	WIRE-128-7	'
    |	SCR-538-(a)	(SEE NOTES)//
    Figure 4. Cording diagram of Radio Set SCR-508-{&), SCR-528-{&'), or SCR-538-(&) and interphone equipment in Medium Tank M4 series.
    13
    14
    HOLES FOR MOUNTING/ .BRACKET FOR MOUNTING RADIO ANO /BRACKET FOR BRITISH CONTROL UNIT*2 BRACKET FOR SCR-5O6-(i) SEE EN-/ / INTERPHONE SWITCH BOX BC-658	/
    MOUNTING \ LARGED VIEW /	/ (ON CEILING)	,	/ SPACER SPACER BRACKET
    MAST BASE MP-\	/	/ /BRACKET	J	/ /	\
    37 OR MP-57	\	/	/	/	/	\	/
    BRACKET	----Lgl-.J. Zl4-._ i ■ /	RICH ’ SPONSbN /	7	/
    / /fl
    terminal eox._ /	—4//--	——?—\
    SPACER—-	‘	____f //>Z	___________
    ■1 "V	~7	/	~r~----	NOTE*
    -L-lX	y/// 4-	\( 'X'vKlT /bRIT?SKhVr°aLMBaT#9 I	LORDNANCE DEPARTMENT SHALL
    ■ J-*	(	))!/(//. I	/ f	V.VM/rK /	FURNISH AND INSTALL ALL
    -	In/x. Zj/J/ /	|	Xf\j\'I \/	BRACKETS.
    Ufo	y \K • zo< ^7/8" DRILL THROUGH TURRET
    _____L	5
    x	SPACER-------\	-X/^-SLIP RING BOX	—TERMINAL BOX	*
    5	— X—Z/Jl \ \ \ t--45"--------J 'x	/ I* ! /• I "'"BRACKET FOR MOUNTING	n-
    L	BRACKET^^S^^ZW	TERM.NALBOX	<
    °	//	XS\\\\	~	a x-	----BASE FOR MOUNTING MAST	K
    z	I	YVlVxW''	7	7“L V	BASE MP-37 OR MP-48 OR	l7/fe4” DRILL 12 HOLES
    °	Z7\\\\\	J___°® I V-.'SCx	''.BRITISH AERIAL BASE #8	/ FOR MOUNTING RADIO SET SCR-506"(4)
    U.	xZf \\\\ X	C—MAST BASE PLATE	/
    '	i2n_J \\' > \ bracket-X—<	; Zvxz'R2'	*	/
    X.	-X / ilis-Z	' X	--------— "j-5T---
    \	\	<©> ^spacer	5“'£9^-±^i--4-6+r
    X\	I	'BRACKET FOR BRITISH CONTROL UNIT* I	/	///	j \	'. I _____i-{/t-
    -------_____-------------LEFT SPONSON(_____	_______________________________Z/V	__________-.-4----	' | ( PLAN VIEW----------------/SPACER FOR MOUNTING HOOKS_______________//	=Jr RIGHT SPONSON FLOOR 7
    FAR SIDE-. / /FAR SIDE AND NEAR SIDE	z2-Z------------)___________0 S0N FLOOR__
    BRACKET-x	A /	/
    '	/\	/ \\	/	/	“-------T0 PBONT OF TANK
    /—H	x/AvO-i	k--------------------s<— --------------J
    / zf-J |a"L9L^£\(oI_A| \ I 'JLX>Z	enlarged view OF RIGHT SPONSON
    brackst-^_	/	I g-fr-—r-Yt-« -ffl y r
    nV’-T'jlf o
    /	-,o.« I	C*» V- «>	8-=l I a I
    /	LfLu-^---Hr-----1 7£i = l R- -1- 2I2	,
    /	-sl- o |- ■ ■' -	~t t y ~ j ।
    / EARS.DE---------tA LJ f !	I "T\
    i'	—r-------	,i|	■ ■s?^s?==-==__	~	——-y -'B	/
    SPACER*.	^r1---1L_	—=E~—/ I •/
    \	x<> ,x4A '.	^- BRACKET (FOR MOUNT-U-33"--/_	|	-_____	H	( U /
    X.	'	ING TWO INTERPHONE	/ I	--- |. x I"	/	>	I T
    \	______________ -	J	'
    -----------------------60%--------H TOP OF FLOOR-------/	Tl -1OAR3 T?-----------------------------------------------------------------------/	SECTION A-A	TL 10663
    ‘V	SIDE VIEW	BASEDON
    SC-D-6763-E
    Figure 5. Installation of radio and interphone brackets in Medium Tank M4 series, cast hull construction.
    -. H3eF9i£—l3eF9e"Hsli'*-7-7Z3’----H - z-x
    /4 20 TAP 12 M0LES IN FLOOR OF SPONSON
    flH........-40^^-^=	= /J - . I ■■	.1	;,	1.
    I—'4-4-'°£-d	'!
    IT	fn:u_______________t_____
    —-----------------------------|/z ~~ \x\—:-----------------n~
    ’“ I	/// /	/iz	>?W/2 !	NOTE’
    (S' l( ,	\\	//' /	//	'	ry	ITEMS SHOWN BELOW ARE INSTALLEO
    ~f	I "J?	// ' /	I	NlViS	BY TANK MANUFACTURER.
    t ■	'L AuA/	________—
    —I--4"	7/	/	\X	//'	/	ITEM NO. NAME OF ITEM NO.INSTALLEO
    _1---4---1--Gvf=“d^f f D	0 SPACER	I
    __________i ■ {■; y________r-P-. --.	— _l_<1—<-!4--Z--—■>---------t tank	‘---------------- ’__________	—---"®	”	//	)	TL‘10664
    \. \ x.	ife-.-Jir^	k / /	BASED ON
    \	!'	7 /	SC-0-B423-I
    Figure 6. Installation of radio and interphone brackets in Medium Tank M4 series, welded hull construction.
    15
    16
    TERMINAL BOX
    IN HULL	--CONDUIT
    	*18 RED________________________________A____________ 6l	40—____ *18 YELLOW_____________________
    	I *18 BLUE SHIELDED________________________________ i2	so—______*18 GREEN SHIELDED
    yn________	*i2 black -	- I
    03	60'------ -------------------------------------
    |_______________O-----CONDUIT
    ~^-*lft	IN TURRET
    / ‘-TO COMMON /	GROUND ALL WIRING, TERMINAL BOXES AND SLIP RING
    ^-SHALL BE	ASSEMBLY SHALL BE FURNISHED AND INSTALLED
    SECURELY	BY MANUFACTURER OF VEHICLE.
    SOLDERED	ALL. SHIELDS ON SHIELDED WIRES SHALL BE
    GROUNDED ON BOTH ENDS. THESE TERMINAL BOXES ARE TO BE USED FOR RADIO AND INTERPHONE WIRING ONLY. WIRE SIZES INDICATED ARE B8.S GAUGE
    BASED ON
    SC-A-6758-D	TL-10665'
    Figure 7. Wiring diagram of slip rings and terminal boxes in 24-volt tanks and armored cars.
    L--------„£.--------1-------, 21“---------.
    I**	l"
    BRACKET--------	---------------• •---------;-----142-------•	„
    «----------~7~~-——_--------------------34I------------------—  -------I2£ ABOVE BULGE SHELF
    / BULGE AT REAR )F TURRET 4	r—---	__
    ------------------— — — — —— —	__----------------------------SPACER
    / / / Z ' fe--------------------------1	\+\ \
    /	!	/ T	---------- ’	\	\ V—RADIO BRACKET	NOTE-
    II	—-T'	*-♦	""--L	\	\Z\	BRACKETS SHALL BE PAINTED TO
    /	/	/	-- . <»	4-- \ 7	\	CONFORM TO COLOR OF SURROUND-
    /	/	/	--1	’	•	.	I.	\	\	\	ING AREA OF TANK AFTER BEING
    ' / s'' I	-------------------- [' I	\	\	\	INSTALLED.
    / // /	/\	\ V\
    // / /	'*/* ‘--------------V	J x'xx
    / / s' s'	-------10£------H ' \	ZX x
    x ZZ '\Z	J	uj	^TERMINAL BOX	''Xk’
    x 7	«	%	-	\ /
    X /	to	0:	X
    -------------_____ J I ____________________________________
    r OF TURRET	(
    ------------------------------------------------if-------------- \ x	Xu INSIDE VIEW-------------------------------------,.	\ xx X.
    COVER PLATE--->	0RILL	(	X^x
    /_______________________________________t/______ .MAST BASE PLATE	1	^X
    /	25°ia'—\ x^3^X\	)
    /	Zz—E—x\	tC/'k’ ^x\\ \	[	r.
    /	° . °	|	///\ JL \\\ \	\ BRACKET x *j|	________
    / ------------oJU” -----------------------------------\	/	SPACER—>q
    / 'MAST BASE BRACKET U I \ U •	\\	''A 457/	\	(	I
    / FOR MOUNTING BRITISH 1 \ 7"	\\ A X //	\	\	1
    / AERIAL BASE #9	Vi DRILL	\N^	\	\	1	'
    /	o-,r	\	I	1	=-i~
    /	-------------------2 2 if	\	\	|	CJ CJ
    /	FOR MOUNTING MAST \	)	|
    /	L,___________14I"________» BASE MP-37 OR MP-48 \	7	u
    /	4	OR BRITISH AERIAL SyS
    /	BASE #8	y
    7	top view	7	y	, — o ij
    y	/	L------ _------■--------tXTJTZi--}
    <	/	1=------------------------ -------- 1— -*—
    ---x^^	________________________________________________________y/	X.	//_____y fTL-12317 ‘	*--------------------------------- f	Z-.____I VIEW A-A BASED ON
    V	y	SC-D-5348
    Figure 8. Installation and details of radio ^brackets in turret of Medium Tank M4 series.
    17
    .CONNECT SHIELDING
    /TO GROUND TERMINAL
    / OF RECEIVER
    C.	.1/4' SHIELDED CABLE , SINGLE CONDUCTOR,
    --------------- /APPROXIMATELY 20 FEET LONG. SHIELDING a--------------/ MUST NOT COME IN CONTACT AT ENDS
    u	/ WITH CENTER CONDUCTOR	7^
    RECEIVEBo MTHmTWh- -™gmghT7]7Bn>. ------------l?i	\'	»| 1 Fj । 11 xW00D HANDLE	I—-1
    ----------'	./4-T.36-	(-(I ~ 1—r f---------A jzf/b
    (g__ ____r
    L, J	Q TAPE ENTIRE ASSEMBLY	11	5)
    fl M	J r
    P H	(2) STUFF END OF INSULATED TUBING WITH FELT AND TAPE OVER	___
    j \\ HEADSET	ENTIRE ASSEMBLY	—
    'X ))	(3) WIND 3 TURNS NO. 16 OR NO. 18 ON TUBE OF INSULATING	®	"
    MATERIAL. SOLDER ONE END TO SHIELD ON CABLE, THE	. . _
    OTHER END ON INSULATED WIRE INSIDE CABLE.	h—I 1/4 —1
    (4) FOLD BACK END OF BRAIDED SHIELDING, SOLDER FOLD TO ‘	MAIN SHIELDING.	TL
    Figure 9. Probe antenna.
    18

    PREPARATION OF CORDAGE'
    j£ L_^'_Jz L ri /OUTER INSULATOR
    TIN CONDUCTOR->km	)
    INNER INSULATIOl/^SHOULD BE FOLDED OVER OUTER INSULATION.
    CUT AS SHOWN	I
    'WRAP 5 TURNS OF #18 OR #20 SOLID COPPER WIRE OVER BRAID,. FOLD BRAID BACK AND. SECURELY SOLDER WIRE TO SHIELD WITHOUT DAMAGING CONDUCTOR INSULATION.
    PRE-ASSEMBLY	/SLIDE @© AND © OVER © SOLDER TINNED
    / CONDUCTOR SECURELY TO LUG ON
    □nt Ar n I: B [ ME H □
    f U--'SOLDERING | _____= = gyWW
    A	LUG A	A
    © © © © ©
    SLIDE ©,© AND@OVER CORDAGE©, THEN SOLDER CONDUCTOR TO LUG ON©.
    ASSEMBLY	__= -g h===k	^/CORDAGE 00*282
    (lISsiA3
    HOLD © FIRMLY. SCRE W©TO©THE N © TO© FINALLY FASTEN CLAMP©) OVER PREPARED BRAID. (DO NOT CRUSH BRAID WHEN FASTENING CLAMP©).
    based ON	TL-I0I33
    SC-A-7075-A
    Figure 10. Coaxial connector for Mast Base MP-48 and Cord CO-282, assembly for installations.
    20
    /[{^SCREWS (2) TO
    SECURE MAST SECTIONS
    ZA/ z-n
    ° " -(9JSCREW TO SECURE
    gh/ <>LEAD~IN
    '\^T^(7?)soldering plug
    J	teh-*—(l6A)
    O—A	IH	w
    LAPP COUPLING *26243 (j?) (jg)
    I -J	jj- (I6C)
    “1	-l-T-l* (INNER conductor solder
    flfl	i . SMALL- hole ,N
    flfl	—hW^AINNER INSULATION CUT
    flfl	COAXIAL CORDAGE @L “l. F|	CO-282 OR CABLE WC-5^2\^	\\ (SHIELD CUT BACK 1/2’SLIP
    V	‘ (fl)FLAT WASHER	\fV \ N @ OVER END OF CABLE.
    J I I /X'	\ [SCREW (l6A) INTO (l6B).
    Z t^^JX®L0CKWASHER	\(OUTER INSULATION CUT
    (g) 4(4)HEX nut	(.BACK I"
    _	HkAYT)bottom of mast base’
    (ir\—PREPARATION 8. ASSEMBLY OF \NEOPRENE WASHER	COAXIAL COUPLING & CORDAGE
    ^7 V\ \T?)cERAMIC WASHERS (2)
    fl \ Q3)lNSULAT0R
    \?I2)PIN
    Q5)adapter coupling
    CORD CD-689 FQR COAXIAL LEAChrIN CONNECTION.
    SECURE PLUG Q|) WITH SCREW (9). SCREW Q5J INTO	BASED ON
    BOTTOM OF MAST BASE TO SECURE ASSEMBLY;	SC-A-7I65-A	TL-I0I32
    Figure 11. Mast Base MP-48—A, assembly with coaxial lead-in.
    21
    J® SCREWS (2) TO
    // SECURE MAST SECTIONS
    ~ 1	SCREW TO SECURE LEAD-IN	rn—>
    xll/i SOLDERING PLUG	/
    F	?	SOLDERING LUG /
    £7	?	STRIP INSULATION z^S
    £=■	<	FROM 1/2" OF
    WIRE SOLDER TO LUG
    I--r®4»?	©'-"*E fl
    ---------- INSULATORS IN-118.------/
    ' rJ @FLAT WASHER
    <	'/C® LOCK was her	\
    "	@ HEX NUT	s' X^JW»
    BOTTOM OF MAST BASE
    NEOPRENE WASHER	WIRE W-128, external lead-
    M	IN. CUT TO 25" FOR SCR-5IO-(&)
    ,	(5) CERAMIC WASHERS (2)	OR 37" FOR SCR-6IO-(&). STRIP
    ppINSULATION FROM 1/2"OF ENDS /7J^,R,E^ED PHENOLIC	OF WIRE AND SOLDER-TIN. PASS
    — V	COLLAR	THROUGH @ & 05).LEAVE SLACK
    \	FOR FLEXING MAST BASE. _
    'WIRE W-128 INTERNAL LEAD-IN FOR	SOLDERNTERkflNAL TO^NR^F
    SERIES SCR-508,608,708,808 RADIO	WRE FOR cXeCTIoS TO
    SETS. SCREW ® INTO BOTTOM OF MAST ranirT^rt °NNECT °N T° BASE. TO SECURE LEAD-IN ASSEMBLY,	KAUIU SET.
    CUT WIRE TO REQUIRED LENGTH. (NOT
    OVER 52")
    BASED ON
    SC-A-7I66-A	TL-I0I34
    Figure 12. Mast Base MP-48-A, assembly zvith Wire W-128 lead-in.
    APPENDIX
    IGNITION NOISE SUPPRESSION IN MEDIUM TANK M4 SERIES
    1. General.
    Excessive ignition or other electrical noises may interfere with the operation of radio equipment in Medium Tank M4 series. The Technical Manual issued with the tank will be helpful in locating the source of noise since it describes the suppression systems used. Instructions for operating radio and interphone equipment used in Medium Tank M4 series should also be studied.
    2. Procedure.
    Locate and suppress ignition noise as follows: a. Start the tank motor and turn on the radio
    Interference
    Popping sound; corresponds to ignition firing; accelerates when engine is raced, stops when engine is turned off.
    Intermittent, clicking sound; lingers for several seconds when ignition is turned off.
    Whining sound; varies with speed of engine; ceases only when generator stops rotating.
    Sparking, or continuous crackling noise.
    d. Interference from other electrical parts and circuits of the vehicle, such as panel gauges, heater fans, and, in vehicles with turrets, traversing motors and gyrostabilizers, can usually be identified by turning off the gauges, fans, or other suspected mechanisms, individually.
    e. If the source of interference cannot be found by any of the preceding methods, connect a probe antenna (fig. 9) to the antenna terminal of the radio set. Move the loop of the probe antenna slowly over the various parts of the vehicle’s electrical system. Keep the loop close to, but not in contact with, the part being examined. Interference-producing parts should be heard in the receiver.
    receiver. Put the receiver sensitivity control at maximum. Then, listening to the receiver output with a handset, tune the receiver slowly over the entire range of frequencies to be used for communication.
    b. When the frequency (or frequencies) with greatest noise level is found, turn off the vehicle engine. If interference persists, the source is outside the ignition system. If noise stops, the trouble is in the ignition system.
    c. Start the engine again. Adjust the receiver sensitivity control until engine noises can be distinguished most easily from static, etc. Interference may then be identified as follows:
    Usual source
    T * •	*
    Ignition system.
    Generator regulator.
    Generator.
    Brushes and commutator of generator.
    /. Interference can generally be eliminated by cleaning, tightening, or replacing noise-producing parts. All suppressor and shielding components and all connections and grounding bonds should be examined, tightened, and the surfaces under them cleaned. This will assure good electrical contact between wires and terminals, and metal casings and the frame of the vehicles. (Insulated but ungrounded metal parts absorb and reradiate electrical noises.)
    g. If interference persists, suppressor components should be checked by substituting new ones. If a replacement is not available, disconnect the suspected component, and test capacitors, resistors, and chokes within it, for opens, shorts, or other faults.
    22
    NTSU LIBRARY
    UNT LIBRARIES DENTON TX 78203
    1001896166