    [Telephone Central Office Set Tc-4]
    [From the U.S. Government Publishing Office, www.gpo.gov]

    ﻿vaseui-33j- mmHiw—’ TM 11-332
    Document--------------—
    Reserve WAR DEPARTMENT
    TECHNICAL MANUAL
    TELEPHONE CENTRAL OFFICE SET TC-4
    June 1, 1942
    NON-CIRCULATING
    NTSU LIBRARY
    WVS5".
    TECHNICAL MANUAL
    TM 11-332 C 1
    TELEPHONE CENTRAL OFFICE SET TC-4
    Changes]	WAR DEPARTMENT,
    No. 1 J	Washington, December 14,1942.
    TM 11-332, June 1, 1942, is changed as follows:
    6. Switchboard operation.
    *******
    /. Grouping key.
    (3) The A and B leads are common to all cord circuits in the switchboard (see fig. 9) and are used to complete the operator’s transmitter battery circuit (see figs. 11 and 11 ¥2) whenever a key is operated to the TALK position. Switchboards other than those manufactured under the order numbers mentioned in (2) above are wired as shown in figure 11 ¥2- With the grouping key thrown, it is thus necessary to operate only the talk key on the unattended switchboard in order to obtain transmitter battery at the attended switchboard. In the switchboards manufactured under these order numbers, operation of the grouping key does not provide for transferring the A and B leads from the unattended switchboard to the attended switchboard as shown in figure 11; thus, when the grouping key * * * in order of preference:
    *******
    [A. G. 062.11 (11-20-42).] (C 1, Dec. 14, 1942.)
    497889°—42
    ntsu LIBRARY

    TELEPHONE
    CENTRAL OFFICE SET TC-4
    TM 11-332
    C 1
    TO CORO CIRCUITS ond 2d CURATORS	TO CORD
    >	TELEPHONE CIRCUIT	CIRCUIT
    P	/------\	P—U-P
    o	_______________________r
    to
    p^.
    H	p2 O---------T---------’•	------------J----OB2X
    ■	P	p
    r	R2o-----—1——	(■——i——o*2
    bi GROUPING _	_ GROUPING
    T" TERMS “I	TERMS
    T'O---------1-------- f—--------------j-----OB'
    ~	p I T l I p	ext 0AT
    2 [ri o----------------J-----• k th rp H------—1-------OAiJ	OPVV
    Q	BINDING POSTS	; K I---------------\	A A Binding POSTS-
    bO J?	ON TERM PANEL----------------------------'-- BINDING POSTS U	ON TERMINAL
    --------j---O'	ON TERM PANEL	PANEL
    t	wev /GROUPING t \	- o »
    ( OFF - ON J	Tj
    £	SW-C9	3	P	f EXT BAT)	/BATTERY)
    £	k	IoFF-onJ k 1-2 J
    w	, L	f-----
    -	-----P---------------------------------p>—_________________ j
    3 COIL	~~T	§ 1 KFY
    i c-'05	rti-. KEY
    3 1_______1	___„ —-----! KEY	I___
    A	in ■	■ ■ —
    2	T --------*	1	-	-
    — 3V	— 3V
    (	JK 37 J*	7+
    0 2S_L	f----—'------°---C
    MF -r-	VA	_____1____________
    05^r	TVaristor,
    --------j |-----U-------i-------5----o---a Figure IV/z.—First operator’s telephone circuit.
    TM 11-332
    TELEPHONE CENTRAL OFFICE SET TC-4 C 1
    Figure 15 is rescinded and the following is substituted therefor:
    TRUNK CIRCUIT
    COMMON BATT CRY MANUAL
    MAGNETO LINE CIRCUIT	CORD CIRCUIT	(T)
    nt—!——------------------
    . TP I I r-4 . I ______________________________________________ F ffF ।
    | T _____|	.	(ANSWER)	«7OJ	n----1-—H	“ I	(CALL)	4	pF W—f
    l“°	। j! ।	p-=!	-=p1	™
    11 j	■ r n> -J -	•—
    f	1--------If—--‘ ■	------1-------Lo«
    f—--------------- Bl NO I NG POSTS
    _____________________________ ON TERMINAL I” CORDS I-B INCL. MULTIPLE©_<- V- ALL COROS \	L	PANEL
    V. <-	TOGETHER	MULTIPLE© TOGETHER
    COROS 9-i2 INCL. MULTIPLE©	Z'Wd Ol*L C0*° C'*CUlT
    TOGETHER	fA
    CONFERENCE CIRCUIT	0UL ( Pff H )
    z-	f T A f>~^-0
    p- -	---D	T LEAD	*«• LEAD	> |__J?—C
    	J	, >K>c-_	°____«<4.)	J Ij,
    0 --P— —-	n	J	- -*   RINGING CIRCUIT
    •____I ---------——KEY
    «’ (^-^),
    ?► P J	- p J	SECSND OPERATOR'S	r— ■—	r—«, «—-r-*A\—
    rEuEP«HE	rr	~ dr	%
    A» At B,Nt>,NC POST*	4	'/ ",NC,NC
    J.CKS		■	■	।---------------y--O?|	GENERATOR
    R2O—----•--- ------------1__Q;	T"! 0___ _? I KEY
    -]	1 n “J	(NIGHT ALARM)
    T> O---T---U|	p4-----J---Of I	i—OFF-ON )
    RJ o---1---- .. L p J p --1-oaix	f c^R y
    Binding POSTS	I t t-------\	A A BINDING POSTS	_ X
    ON TERM NWL	1------------ POSTS	U ON TERMINAL	------~O~1
    «v(3~£FT1	™~4 er
    L_"’___________ H--) <‘ST2_	—J—o-J
    TELEPHONE OOJT	... -A-1	20--J - ■ . —	>■ .	I	BINDING POSTS
    S	«—	■	Q	ON TERMINAL
    1 c%	c r=n	KET
    ret	3y----- r	•«* t 1-
    «»C3. JOOTfOUC	3	I i---« r
    mokmal crwiATEO	p	T	~ JV	— Sv
    OA !’«•"	‘f	|	JK-JT -p P
    a ♦	D2S±	-----f-----• C JACK
    |	------------1
    Figure 15.—Switchboard BD—96, master schematic diagram.
    [A. G. 062.11 (11-20-42).] (C 1, Dec. 14, 1942.)
    By order of the Secretary of War :
    G. C. MARSHALL, Chief of Staff.
    Official :
    J. A. ULIO,
    Major General,
    The Adjutant General.
    3
    U. S. GOVERNMENT PRINTING OFFICE: 1942
    I
    A 3^; Z7'3™ ct333
    TECHNICAL MANUAL
    TELEPHONE CENTRAL OFFICE SET TC-4
    Changes No. 2
    WAR DEPARTMENT, Washington, May 12, 1943.
    TM 11-332, June 1, 1942, is changed as follows: 2. Component parts.
    			Approximate	Approximate
    Quantity	Article		shipping size (inches')	unit weight (pounds')
    1	Switchboard BD-96		—	15 x 22 x 25	200
    1	Panel BD-97			11 X. 241/2 X 271/2	150
    20	Batteries BA-30; 10 in	use, 10	214 x I14 dia.	¥4
    4	spare. Batteries BA-23; 2 in	use, 2	6^ x 2x/2 dia.	2
    1	spare.1 Converter M—222 1			814 x 6% x 6%	101/2
    1	Cord CO-258			(50 ft. long)	10
    1	Cord CD-451			(20 ft. long)	1
    ’I	Ground rod GP-16		—	24 x 1/2 dia.	iy2
    1	Ground rod GP—29		—	36 x 1% dia.	10
    2	Chest sets TD-1 2
    2	Head and chest sets HS-	19 2			2
    2	Headsets HS-30-( )2_			1
    1	Maintenance equipment	ME-11	20 x 39 x 19	200
    1	(in chest CH-65). Paulin, duck (type I) 12.3 ft. x		36 x 24 x 18 (folded) 55
    2	16 ft., equipped with not less than 10 grommets with 5y2 ft. tie ropes. Telephones EE-8-A			4 x 71/2 x 10	9¥2
    Total weight approximately______________________
    673
    1	Converter M—222 and batteries BA-23 are used to supply-power ringing to switchboard BD-96 when the 110-volt 60-cycle a-c supply required for the Telering fails or is not available. For description, see TM 11—344.
    2	When chest sets TD— 1 and headsets HS-30-( ) are not available, head and chest set HS—19 may be used.
    [A. G. 062.11 (4-6-43).] (C 2, May 12, 1943.)
    524101°—43
    NTSU LIBRARY
    TM 11-332
    C 2
    TECHNICAL MANUAL
    21. List of parts.
    *	* *	*	* *	*
    a. Telephone central office set TC-4,			complete and composed of
    the following items: Stock No.	Name		Description	Function	Ret. par.
    4C9996.6	Switchboard	BD-96	Switching central	21&
    4E3697	Panel	BD-97	Distributing and	21c
    3A30	Battery	BA-30	protector frame Furnish voice
    3A23	Battery-	BA-23	current For Converter
    4F222	Converter	M-222	M-222 Emergency
    3E2258	Cord	CO-258	ringing current Ground connec-
    3E1451	Cord	CD-451	tion Ringing power
    5B4416	Ground rod	GP-16	Ground
    3Z3329	Ground rod	GP-29	Ground
    	Chest set	TD-1	Part of opera-	21g
    4B1279	Head and	HS-19	tor’s set Operator’s set	21e
    2B830( )	chest set Headset	HS—30—( )	Part of opera-	21/z
    4C5611	Maintenance	ME-11	tor’s set Storage for spare	21-ton truck is used, components of the telegraph central office set TC-3 (teletypewriter) will also be transported and operated in the truck with the TC-4. The plan provides essential equipment for installation at a division command post or at a rear echelon of a division headquarters.
    2. Construction.—a. The mobile telephone central office consists of an O-truck, 1%-ton, cargo, or an O-truck, 2i/2-ton, cargo, with all equipment loaded in packaged form (that is, so far as possible carried as units or in suitable chests). This will provide for the temporary installation of the telephone central office in the truck when conditions permit, or for the rapid removal of the equipment for installation on the ground or in shelter when necessary, or when the truck is required for other work. Three of these trucks may be thus equipped for each division signal company.
    A The list of equipment necessary for the construction of a mobile telephone central at the echelons of division headquarters is given in the following loading tables:
    5
    TM 11-332
    C 2
    TECHNICAL MANUAL
    Signal Corps stock number	Item	Number required when using
    		O-truck IJ^-ton, cargo		O-truck 2J4-ton, cargo
    		Rear echelon	First or second echelon	Rear echelon	First or second echelon
    Central office 4C27004	 4A2788	 Nonexpendabl 6Q1001		sets Telephone central office set TC-4 Telegraph central office set TC-3 (teletypewriter) e items Ax LC-1	 Axle RL-27-( )	 Blackout light1	 Cable assembly CC-345, 100 ft. long (5 pr.). Cable assembly CC-345, mile long (5 pr.). Cable stub CC-344, 10 ft. long (5 pr.). Chest BC-5	 Flashlight TL-122-A	 Gloves LC—10, pr	 Reel DR-4	1		1		1	 1	1 1 1 1 2 6 3 10 3 3 3 2 1 3 1 1 24 5 2 54 1 1 20 ft. 100 ft. 100 6 6
    		1	 1	 2	 4	 2	 6__	1	 1	 2	 6	 3	 10	 3	 3	 3		1	1	1	1	1	1	Illi T-I rH CM Tff	CM	O	CM CO CO CM
    6H227( )	 1B1445
    Do
    1B1444...
    6F705 _.
    		2	 3	 3	 9
    6Z4002A.1— 6Z4810..
    6112504 .
    6H2505. __
    	Reel DR—5		—

    6H2507...
    	Reel DR-7	9	3	2.
    6H6231___
    	Reel unit RL-31	 Sign 2		1	 1.	1	 1	1	 1
    4B5008A	 4E9304	 1B110B	 Expendable ite 3A30
    	Telephone EE-8-A	12	24	 5	 1	 54		12	 3	 1	 30
    	Terminal strip TAI-184	 Wire W—110—B, miles	 ms Battery BA-30	3	 1___ 30
    6Z6981..
    	Camouflage material (standard nets, chicken wire, etc.). Log Book	 Marline RP—9 nnmirlo
    		1		1		1
    6Z7904...
    	Rope RP-1. ball	20 ft___ 100 ft__ 100	 6	 6		20 ft__ _ 100 ft__ 100	 6	 6		20 ft... 100 ft.. 100	 6	 6
    1A16.
    	Seizing wire W-16, spool	 Tags MC-72
    4Z7272..
    6N8594
    	Tape, rubber, TL-94, rolls._ Tape, friction, TL-83, rolls.
    6N8583

    1 Improvise pending standardization. Self-contained battery source, such as BA-23, suggested.
    3 Improvise pending standardization. Interior-lighted box suggested.
    6
    TM 11-332
    TELEPHONE CENTRAL OFFICE SET TC-4 C 2
    c. When the O-trucks, 2%-ton, cargo, are used, the following telegraph equipment may be carried in the O-trailer, 1-ton, 2-wheel, cargo, attached to the first echelon truck when a movement of the command post is being made:
    2 teletypewriter sets EE-97-A
    2 telegraph sets TG-5-A
    d. The suggested loading plans are shown as follows:
    Figure	Loading plan for	Using O-truck
    21	Movement	1^/2-ton, cargo,
    22	Operation	Do.
    23	Movement	2%-ton, cargo.
    24	Operation	Do.
    The loading plan is the same for each of the three trucks of a company, except that in the case of a rear echelon truck, a reduced amount of equipment is carried in accordance with the table in 6 above.
    e. Three chests BC-5 are provided for loading telephones and other small parts included in the list in b above. This will permit greater ease of transportation. All of the smaller component parts of the TC-4 are carried in the compartment provided in switchboard BD-96 except maintenance equipment ME-11, which is carried in chest CH-65.
    3. Installation of equipment.—a. It will be noted that figure 24 shows the location of the cables from panel BD-97 to switchboard BD-96. Tie these cables to the canopy bows just above the top edge of the metal part of the body. In this manner, the cables are kept up off the floor. Do not pass the terminal strips and the cables around the outside of the bows since this would prevent removal of the telephone equipment from the truck without disassembling the terminal strip from the switchboard.
    b. The method of leading in the outside lines is a matter which the installation personnel must work out for individual cases. In general, it is desirable to “bunch” or tie the wires leading into the truck together for a short distance to the nearest support. The purpose of tying the field wire lines and field cables together is to prevent sagging of individual wires. If an installation is made in a truck, it is likely that the truck will be located near trees or underneath a camouflage net which has supports at the outer edge. It is desirable that these lines be suspended higher than a man’s head for a distance of approximately 25 to 100 feet away from the truck in order to prevent damage to them and also in order to prevent injuries to personnel which would result from insufficient ground clearance.
    7
    TM 11-332
    C 2
    TECHNICAL MANUAL
    I 6W
    Truck cargo j
    C/ies/ SCS Ches/ bCS
    (/2 Te/ep/iones TT8) (tZTe/ep/wes ® ®
    Sw/7cAbodrrf Ches/ C77~65'
    BD ~76	LM3,n/en3d^d i,)
    Cqu/pmenr MC-//J
    ®/kee! DR~7\ I w//h \ Pare/ \//sse777/j/y j
    ®/Pw/fh \ ^&Cat>/e\ \F^MTe\ \A^' w-//O-5 J \^5-\ \ 72 m/. /	/oo ft
    y '---------J
    Ctiesf^C-S
    (Sma// par /'S &	r---------
    /?x/e/P/.-27-/!
    344, a/w3 ca3>/e
    'S'jpp CC-345	----------
    777/7777/
    s/r/p T/4-/34)
    l— '	-@J -------------------------
    TL-626O
    Figure 21.—Loading plan for movement, TC-4 in 1%-ton truck.
    8
    TM 11-332
    TWT.FPTTmVT?. CTT/MTR AT. mHTTrP.' STT.fr TC-1	n 9.
    ru-626/
    Figure 22.—Loading plan for operation, TC-4 in 1%-ton truck.
    9
    CAE) Truck	cur^o ,
    £==:< -------------- .
    Chest 3CJ	Ches/ 3C~5
    (izTe/ephores EEh)	(12Te/e^bo77esEE-d)
    C/yes/ CH~6§ Meh boa rd (Md/n/enarce . nr. Equipment ME-11)	E>D-96
    Pane/
    B/P97
    TM 11-332
    C 2
    TECHNICAL MANUAL
    I CPE
    | Truck 2 7>-ton, cargo TCP in lEEee/ Ease on
    SW3DSD%
    (izTeiepbo, TC-4-
    CHEST BCS
    -r.. ones
    ee-c-a)
    CHEST BC-S (/2 Te/epEones
    CHEST CH~6y-
    CHEST CH-62-A
    CPestCPSOA
    ■Tor Pr/rfer7c-7A
    farlo/TC-3
    Chest bc-s (5m//es\ cc-39E-/oqf
    /cee/PE3\ f w/W?J ) field W/re \w-//o-s J
    fee/ (fp/f 27.31
    /Me PL-27-ft
    TL-6262
    Figure 23.—Loading plan for movement, TC-4 in 2%-ton truck.
    10
    TM 11-332
    TELEPHONE CENTRAL OFFICE SET TC~4 C 2
    •	- Cab -
    Truc/c Ph?-tor? cargo 1/(5/r?ct? cu/?eet base o??/y
    Chest 8C5 Chest BCS H
    (/ZTe/eprfones^	(iPTe/e/rtopes,
    \Chest Cf/7b\ |£^| fr Parts	C^'SJ
    Part of	riper
    res	„etc,
    -----------y\ tert of
    \Ches/BC-5\	/' I
    (5ma//parts	/Si TPs
    & 5 cabte	/	Ptace Pourer
    stirbCC-344	/	Eporpme/ttas
    z
    ^ jitfBP \\	k
    --m---- I------1	U
    JW/7	11
    Sff-^6	f^ \	—
    &Uo/ \SS? I	Co'62;/>
    7C~4	\	!	Pectif/'er
    C/tesf	.
    Cff-6S	ttarttf
    Tc-3
    (Afa//?teaaace	' ._ Jp)
    A iffrCt ?
    tec-JJ	((	BD-97
    Port of	<0	r r u
    7C4	/
    2	°r
    8	rc-4

    Figure 24.—Loading plan for operation, TC-4 in 2%-ton truck.
    11
    TM 11-332
    C 2	TECHNICAL MANUAL
    c. Ill order to permit personnel to enter or leave the truck under blackout conditions without extinguishing the lights, the use of paulin, duck, type I, furnished as part of telephone central office set TC-4, is suggested as follows (see fig. 25) : Tie the top part of the paulin over the top of the truck canopy, overlapping about 3 feet, and reaching the ground. Overlap the left-hand vertical edge of the paulin on the side of the truck about 3 feet. The right-hand edge of the paulin will then extend about 4 feet from the right rear end of the truck, and may be attached at the top corner to the top of the truck. This arrangement provides a satisfactory shield so that personnel desiring to enter the truck under blackout conditions can first lift the flap on the right-hand side, walk under the paulin to the rear of the truck, allowing the paulin to fall back in place, and lastly, enter the body.
    4. Operation.—a. The arrangement for operation during blackout conditions will differ, depending upon the degree of security required by the division commander and as determined by the situation.
    (1)	For extremely critical situations, the following precautions will be observed: blackout lights should be installed. Turn these lights off whenever entrance and exit of personnel is taking place. Use the improvised curtain shown in figure 25. and the end curtain of the truck. The only ventilation permitted at night will be by means of natural convection of air currents through the openings between the canopy and end curtain. No other lights will be permitted in or around the mobile telephone central office.
    (2)	In the case where normal restrictions are in effect, entrance and exit of personnel from the truck is permitted with the blackout light turned on, provided the improvised curtain shown in figure 25 is used to seal the opening into the truck from direct view. In this case, the end curtain of the truck need not be used. Increased ventilation may be obtained by propping up the canvas canopy by means of short sticks and retying the ropes to prevent accidental lifting of the canvas by the wind.
    (3)	Under less severe restrictions, such as rear installations where no enemy ground troops would be likely to observe the presence of the mobile telephone central office, and where security against observation by enemy aircraft only is required, the mobile telephone central office may be operated without the end curtain or the improvised entrance curtain in place. It is assured that the blackout lamp used will provide an intensity of illumination so low that the direct ray of the lamp will not be visible at a distance of approximately 1000 feet. Under this condition, any reflected light will be unobservable at a much shorter distance and adequate security will be maintained.
    12
    TM 11-332
    TELEPHONE CENTRAL OFFICE SET TC-4 C 2
    Figure 2a.—Entrance curtain using paulin, duck, type I, part of TC—4.
    13
    "''■Enter here
    TL-6264
    TM 11-332
    C 2	TECHNICAL MANUAL
    b.	When a movement is ordered, load the equipment comprising the mobile telephone central in the truck, and proceed to the location of the iiew command post via the route specified for the movement of the first echelon. The mobile telephone central will proceed to a point as close to the actual command post location as is consistent with the cover available, and the particular conditions of combat. If this location is sufficiently close to the command post to permit installation in the truck, remove the line construction equipment and material from the truck and set up switchboard BD-96 and panel BD-97 in the truck. Install the local circuits and station equipment by making use of such field wire and telephones EE-8-A as are necessary.
    c.	If, on the other hand, the truck cannot proceed to the actual location of the command post, or if it is ordered to remain at some distance from the command post, remove all of the equipment and material from the truck and carry to the proposed installation point.
    d.	In some instances, the telephone central will be located at some distance from the actual command post location. In this event, a decision must be made as to whether field wire or field cable will be used for the installation of local circuits. In the latter case, employ the appropriate number of cable stubs CC-344 and cable assemblies CC-345.
    e.	Axle RL-27-A, reels DR-4 and field wire W-110-B will be used for the construction of local circuits.
    /. In the case where the command post location is some distance removed from the axis, a slightly different procedure will be used. At the point where the circuits branch from the axis, such as a wire head, install terminals TM-184 and cable stubs CC-344. If field cable is being used for the axis circuits, these items need not be installed, but additional lengths of cable assemblies CC-345 will be employed to reach the telephone central location. In either case, as the truck proceeds toward the command post, pay out field cable, making use of reel unit RL-31 and reels DR-7. If the distance is short, use 1 or 2 lengths of cable assemblies CC-345, 100 feet long, to extend the circuit.
    g. In some command post installations, it may be feasible to employ field cable for trunk circuits forward, running the cable from the switchboard location to the point where the field wire circuits start. If this is required, employ the appropriate number of cable stubs CC—344 and cable assemblies CC-345. If field wire only is employed, make the connections directly to panel BD-97.
    14
    TM 11-332
    TELEPHONE CENTRAL OFFICE SET TC-4 C 2
    •
    h. A copy of the Loading Plan for Movement, and a copy of the Loading Plan for Operation should be kept in a clear plastic pocket or envelope and stored in a convenient place so as to be available for reference.
    [A. G. 062.11 (4-6-43).] (C 2, May 12, 1943.)
    By order of the Secretary of War :
    G. C. MARSHALL,
    Chief of Staff.
    Official :
    J. A. ULIO,
    Ma for General,
    The Adjutant General.
    15
    U. 3. GOVERNMENT PRINTING OFFICE: 1943
    CM
    ** TM 11-332
    "	C 3
    TECHNICAL MANUAL
    TELEPHONE CENTRAL OFFICE SET TC-4
    Changes]	WAJR DEPARTMENT,
    No. 3 J	Washington 25, 15 July 1943.
    TAI 11-332, 1 June 1942, is changed as follows:
    All references to Telegraph Central Office Set TC-3 appearing in C 2,12 May 1943, are hereby rescinded.
    [A. G. 300.7 (23 Jun 43).] (C 1, 15 Jul 43.)
    By order of the Secretary of War :
    G. C. MARSHALL, Chief of Staff.
    Official :
    J. A. ULIO, Major General^ The Adjutant General.
    542050° —43
    NTSU LIBRARY.
    tJ. S. GOVERNMENT PRINTING OFFICE: 1943
    TM 11-332
    TECHNICAL MANUAL )
    No. 11-332	)
    WAR DEPARTMENT Washington, June 1, 1942
    TELEPHONE CENTRAL OFFICE SET TD-4
    SECTION I. GENERAL	Paragraphs
    Purpose---------------------------------------- 1
    Component parts-------------------------------- 2
    General description---------------------------- 3
    II.	EMPLOYMENT Equipment layout------------------------------------- 4
    Setting up and connecting equipment------------ 5
    Switchboard operation-------------------------- 6
    III.	DETAILED FUNCTIONING OF PARTS Switchboard BD-96------------------------------------- 7
    Magneto line circuit--------------------------- 8
    Trunk circuit, dial and common battery manual- 9
    Cord circuit---------------------------------- 10
    Ringing circuit------------------------------- 11
    First operator’s telephone circuit------------ 12
    Second operator's telephone circuit----------- 13
    Night alarm circuit--------------------------- 14
    Conference circuit---------------------------- 15
    Master schematic diagram---------------------- 16
    Panel DD-97----------------------------------- 17
    Power ringer, 20-cycle------------------------ 18
    464872 0 - 42 -1
    1
    TH 11-332
    1-2	Signal UOrps
    IV.	SERVICING AND REPAIR Maintenance------------------------------------------  19
    Packing for army	transportation----------------- 20
    V.	REPLACEMENT PARTS List of parte------------------------------------------21
    Addresses of manufacturers---------------------- 22
    SECTION I
    GENERAL
    Paragraph
    Purpose-—-------------------------------------------------------   1
    Component parts—-------------------------------------------------- 2
    General description----------------------------------------------- 3
    1.	PURPOSE. - The switching central, telephone central office set TC—4> is designed for use at division or other headquarters which require a telephone switchboard of the capacity of switchboard BD-96 as described in paragraph 3 a.
    2.	COMPONENT PARTS. -
    Quantity	Article	Approximate Shipping Size	Approximate Weight
    	(Inches)	(Pounds)
    1 Switchboard BD-96	15x22x25	200
    1 Panel BD-97	Ux24|x27i	150
    20 Batteries BA-30; 10 in use, 10 spare	2£xl£ dia.	i
    1 Cord CD-258	(50 ft. long)	10
    1 Cord CD-451	(20 ft. long)	1
    1 Ground rod GP-16	24x^ dia.
    2 Head and chest sets HS-19		2
    1 Maintenance equipment ME-11 1 Paulin, duck (type I) 12.3 ft x 16 ft., equipped with not less than 10 grommets with 5^ ft.	20x39x19	200
    tie ropes	36x24x18(folded) 55
    2 Telephones EE-8-A Total weight approximately —	4x75x10	—21 - 646
    2
    TM 11-332
    Telephone Central Office Set TC-4	3
    3.	GENERAL DESCRIPTION. - The complete installation is shown in figures 1 and 2. Figure 1 shows switchboard BD-96 ready for operation, and figure 2 shows panel BD-97 set up for operation.
    a. Switchboard BD-96. - The switchboard is a complete, transportable, single-position, manually operated telephone switchboard for serving magneto line traffic as well as originating and terminating trunk line and ring-down tie line traffic. Trunk circuits are provided which may be used for connection to common battery lines of either manual or automatic central offices. Drop signals are provided for the lines and trunks and are associated with each cord for recall signrls. The line jacks are wired to a binding post panel in the top of the switchboard which provides for connections with spade-terminal strips through rubber jacketed cable to a panel BD-97 (main distributing frame). Facilities are provided for using two telephone central office sets TC-4 combined as a single office. The batteries which supply current for talking and for the night alarm buzzer are inserted in the rear of the switchboard. Terminal facilities are provided in the top of the switchboard for ringing current, grouping, a second operator, and external battery. Each switchboard contains the following:
    1 First operator's telephone circuit with grouping key
    12 Cord circuits
    1 Ringing circuit
    40 Line circuits, magneto
    4 Trunk circuits, common battery manual or dial
    1 Dial cord circuit
    1 Conference circuit
    1 Night alarm circuit
    1 Second operator's telephone circuit
    In operating position the approximate size of the switchboard is 15 x 22 inches x 47 inches high. The switchboard is arranged to be packed within the angle iron base; therefore a separate packing case is not necessary for Army transportation.
    3
    IM 11-332
    3
    Signal Corps
    b. Panel BD—97» ~ Th® panel BD—97 is a main distributing frame unit for use with one switchboard BD-96. It is equipped with commercial types of high-potential and sneak-current arresters which are wired to binding posts for the incoming lines. The connections between the panel BD—97 and switchboard BD—96 are made with rubber jacketed cables wired directly to the protectors on the panel and equipped with spade-terminal cable connectors (terminal strips) at the switchboard. A 20-cycle power ringer is mounted in the panel for ringing current when 110-volt, 60-cycle power is available. The cabinet is equipped as follows:
    4
    TL-3447
    Figure 1. — Switchboard BD-96 ready for operation.
    TM 11-332
    Telephone Central Office Set TC-4	3
    Line side. - Protectors consisting of 1-ampere fuses and protector blocks (unit dischargers) in two verticals of 22 pairs each.
    Switchboard
    side. - Three 15-pair cables (,44 pairs and ground wire).
    Coil rack. - Eight coils C-161.
    Lower panel.- One 20-cycle power ringer.
    In operating position the approximate size of the panel is 11 x 24g inches x 55 inches high. A separate packing case is not necessary for Army transportation.
    Figure 2. - Panel BD-97 ready for operation.

    5
    BI H-332
    4-5	Signal Corps
    SECTION II
    EMPLOYMENT
    Paragraph Equipment layout-------------------------------------------
    Setting up and connecting equipment------------------------ 5
    Switchboard operation-------------------------------------- &
    4» EQUIPMENT LAYOUT. - Before starting any installation, decide upon the general layout of the equipment in view of the local conditions. Within the limitations of the cable lengths the local conditions will determine the layout.
    5.	SETTING UP AND CONNECTING EQUIPMENT. - a. (1) Turn the switchboard and base upside down. Remove the seat top and extend the extension legs of the base.
    (2)	Ease the equipment to an upright position. Lift the base from over the switchboard, and set it in the location desired for the switchboard.
    (3)	Set the switchboard on the base, making sure the dowels fit in the holes in the top of the base.
    (4)	Unfasten the cord compartment apd let the cords and weights drop into position. Clamp the switchboard to the base by means of the two wing nut bolts.
    (5)	Remove the front cover of the switchboard and raise the designation strips to permit the drops to fall.
    (o)	Fasten the seat top to the switchboard cover for an operator’s chair.
    (7)	Install six batteries BA—30 in the compartment in the lower back of the switchboard.
    (8)	Inspect the switchboard for damaged or loose parts.
    (9)	When two switchboards are to be used together in adjacent
    6
    HI 11-332
    Telephone Central Office Set TC-4	5
    positions, connect grouping terminals T1 and R1 in each switchooard to terminals T2 and R2 of the other switchboard.
    b.	(1) Set the main distributing frame panel BD-97 in the desired location within cabling distance of the switchboard. Loosen the bars on the outside of the case and raise the upper half of the panel (the half without the handles) until it is vertical. Fasten the two lower bars of the upper cabinet to the top bolts of the lower cabinet ao a brace.
    (2)	Unstrap the cables and remove the two angle irons chained to the panel. Fasten these angle irons to the bottom of the lower cabinet as extension legs to make the panel stable. Slots are provided in the angle irons for mounting panel BD-97 either in the center of the angle Irons, or at the end of the angle irons when the panel BD-97 is standing against a wall.
    (3)	When desired, the upper cabinet can be detached and suspended on a wall by means of the hangars at each corner. The 20-cycle power ringer also can be removed from the lower cabinet and hung on a wall when desirea.
    (4)	Connect the three cables to the three rows of binding posts in the top of the switchboard as designated.
    (5)	Install the ground rod and connect it to the ground terminal of panel BD-97. Connect the incoming lines to the binding posts in the upper cabinet, wiring through the repeating coils when desired.
    c.	Terminal and jack numbering. - Line terminals are numbered from 0 to 34 and 39 to 43, inclusive. Trunk terminals are numbered from 35 to 38 inclusive. Termi na~l numbers correspond to line and trunk numbers appearing on the face of the switchboard. (See fig. 3.)
    7
    hi 11-332
    5
    Signal Corps
    Figure 3. - Panel BD-97# protector and terminal panel.
    —• Ground terminal. - The ground terminal in panel BD-97 appears just below the right-hand group of protectors. (See fig. 3.) Cord CO-258 is used to make the connection between the ground terminal in panel BD-97 and the ground rod. Pair number 44 in cords CD-427 is permanently connected to the ground terminal and is used to extend the ground lead from panel BD—97 to switchboard BD—96.
    —• Test the local commercial power circuit, if available, and determine whether it is alternating current or direct current. If 110— volt, 60-cycle, alternating current is available, plug the ringing machine cord into a convenient outlet. Extend ringing current to the switchboard by means of cord CD-451. The connector at the switchboard is located on the panel in the top of the switchboard.
    8
    TM 11-332
    Telephone Central Office Set TC-4 6
    6. SWITCHBOARD OPERATION. - a. The operation of the switchboard is characteristic of comparable commercial practice. See figure 4 for layout of face and keyshelf equipment.
    Figure 4. - Switchboard BD-9&, face and keyshelf equipment.
    b. Incoming calls. - The drop signals indicate a call on a line or trunk. When a call is received, insert the answering (back) plug in the jack associated with the signal and connect the operator to the circuit by operating the TALK-RING key associated with the cord used to the locking TALK position (away from the operator).
    £. Outgoing calls. - To call a number, insert the calling (front) plug in the desired party’s line and operate the key associated with the cord used to the nonlocking RING position (towards the operator) . If the power ringer is not operating, turn the hand generator
    464872 0 - 42 -2
    9
    TM 11-332
    6
    Signal Corps
    while holding the key operated to the RING position.
    d.	Supervision. - Supervision is provided by drops which are located on the face of the board directly above the associated plugs. Ring-off or recall is indicated by these drops falling.
    Figure 5. - Switchboard BD-96, rear equipment.
    e.	Night alarm. - An audible signal is provided by means of the night alarm circuit when desired. Operation of the night alarm key, marked NIGHT ALARM OFF-ON, to the OFF position prevents the audible signal from functioning.
    f.	Grouping key. - (1) A grouping key, marked GROUPING OFF-CN, is provided so that an operator may, during periods of light traffic, use the cords of an adjacent switchboard when two such switchboards are used together. This obviates the necessity of transferring the operator's set to the adjacent board to establish or supervise connections, when only one operator is on duty.
    (2)	In all switchboards manufactured under the following order numbers, it will be necessary, due to conditions described in paragraph (3) below, to use one of several nonstandard operating prac
    10
    IM 11-332
    Telephone Central Office Set TC-4	6
    tices in order to take advantages of the grouping circuit; 1OO-CHI-41, 656O-NI-4I, 6565-NY-4I, and 11U-NY-42. The order number appears on the name plate on the front of the keyshelf.
    (3)	The A and B leads are common to all cord circuits in the switchboard (see fig. 9) ana are used to complete the operator’s transmitter battery circuit (see fig. 11) whenever a key is operated to the TALK position. In the switchboards manufactured under the order numbers mentioned in (2) above, operation of the grouping key does not provide for transferring the A and B leads from the unattended switchboard to the attended switchboard; thus, when the grouping key is operated on the unattended switchboard position the operator at the attended position will not get transmitter battery due to operation of a key to the TALK position on the unattended switchboard. The operation of his own position of switchboard is not affected, however. Following are several ways of overcoming this difficulty, in order of preference:
    (a)	Reserve one cord circuit on the attended switchboard. Operate this key to the TALK position at the same time the key on the unattended switchboard is operated to the TALK position. This operation will close the transmitter battery circuit on the attended position and the operator may then talk on the connection on the unattended switchboard. Both TALK keys should be restored at the same time. The ringing circuit of the unattended switchboard is not affected by the grouping key.
    (b)	A second method involves the use of a telephone EE-8-A in place of the operator’s set. In this method the grouping kqys of both switchboards are operated and the telephone EE-8-A connected to the T1 and R1 or T2 and R2 terminals of either switchboard.
    (c)	A third method is to connect permanently the A and B leads together on the switchboard that will be attended. This method
    11
    TM 11-332
    6	Signal Corps
    causes an abnormal battery drain because the transmitter battery circuit is closed at all times the operator’s set is in the jack.
    (4)	The switchboard cords are of sufficient length to reach apy jack on an adjacent switchboard. It will often be possible to operate two switchboards entirely by means of the cord circuits on the attended switchboard, thus obviating the necessity for using the grouping circuit.
    £. Second operator's telephone circuit. - A key, marked OPERA-TOR 1-2, is provided for disconnecting cord circuits 9 to 12 inclusive, from the operator's telephone circuit and transferring them to the second operator's telephone circuit during periods of heavy traffic. The second operator uses a telephone EE-8—A for an operator's set. Terminals for connecting the second operator's telephone set are located in the top of the switchboard.
    h.	Trunk calls, dial. - Answer the local station in the usual manner, using an answering cord. Insert the corresponding calling cord in the desired trunk line jack (engraved L), and listen for dial tone. '*4ien dial tone is heard, plug the dial cord into the associated dial jack (engraved D) and dial the number. Remove the dial cord and listen for ringing tone. It is not necessary to ring on the trunk.
    i.	Trunk calls, common battery manual. - answer the local station in the usual manner, using an answering cord. Plug the corresponding calling cord into the desired trunk line jack (engraved L). The act of plugging in the trunk line jack signals the manual operator, and it is, therefore, unnecessary to ring on the trunk.
    j.	Trunk calls, supervision. - Care must be exercised in supervising trunk calls involving either dial or manual common battery exchanges, particularly outgoing calls to these exchanges. Momentary interruption of the trunk circuit to these exchanges may result in a
    12
    TM 11-332
    Telephone Central Office Set TC-4	6
    loss of the connection, thus necessitating a complete re-establishment of the call. It may be necessary to monitor the connection occasionally to determine whether the call is still in progress. Since no indication is received from the trunk end of the connection at the completion of a call, a failure of the station to ring off will monopolize the trunk until the condition is observed and disconnection made by the operator.
    k.	Incoming trunk calls. - An incoming call on a trunk line is answered like any other call.
    1.	Conference calls. - To connect a number of lines together for conference purposes, the conference circuit is utilized as follows: Insert the plug of an answering cord in the jack associated with the telephone of the person originating the conference. Then, insert the plug of the associated calling cord in a conference circuit jack. Make the other connections to the conference circuit with answering plugs inserted in the conference circuit jacks and the associated calling plugs connected to the desired line circuit jacks. Call each member of the conference in the usual manner. An alternative method of establishing a conference call, utilizing but one cord circuit for the entire conference, is outlined below. The conference connection is established in the following manner; Insert an answering cord plug in the jack associated with the telephone of the person originating the conference, and connect the corresponding calling cord to a conference circuit jack. Establish the other connections to the conference circuit, using the cal ~l-ing cord of another cord circuit and ringing the called party. After the called party answers, remove the calling cord plug from the jack and complete the connection between the called party’s jack and the conference circuit by means of a patching cord (not issued as a part of telephone central office set TC-4 - see m below). Complete the connec
    13
    BA 11-332
    6	Signal Corps
    tions to the balance of the stations in the conference in a like manner. Upon completion of the conference ring-off supervision is accomplished as usual, except that there is only one supervisory or ring—off drop involved, this being the signal associated with the one cord circuit in use. This one supervisory drop is operated vhen any one of the conference stations rings off. Challenge the call in the usual manner to determine if any other connections are desired.
    m.	Patching cords. - Patching cords consist of two switchboard plugs connected by a piece of switchboard cordage of the desired length. If no standard patching cords are available they may be im-provised out of two switchboard cords whose corresponding terminals are securely fastened together and the two conductors insulated from each other. Occasionally, it may be desired to tie circuits through the board in a semi-permanent manner. This may be done by means of patching cords if it is desired to avoid using a cord circuit. It must be remembered, however, that there is no supervision on circuits connected by means of patching cords.
    SECTION III
    DETAILED FUNCTIONING OF PARTS
    Paragraph
    Switchboard BD-96----------------------------------------------- 7
    Magneto line circuit-------------------------------------------- 8
    Trunk circuit, dial and common battery manual------------------- 9
    Cord circuit--------------------------------------------------- 10
    Ringing circuit------------------------------------------------ 11
    First operator's telephone circuit----------------------------- 12
    Second operator's telephone circuit---------------------------- 13
    Night alarm circuit-------------------------------------------- 14
    Conference circuit--------------------------------------------- 15
    14
    TM 11-332
    Telephone	Central Office Set TC-4	7
    Master schematic diagram--------------------------------------- 16
    Panel BD-97---------------------------------------------------- 17
    Power ringer,	20-cycle---------------------------------------- 18
    7.	S.'/ITCHBOARD BD-96. - a. The switchboard cabinet, base and miscellaneous mechanical details are designed for the mounting and assembly of standard telephone apparatus to form a telephone switchboard suitable for military use. The induction coil, operator's jack, head and chest set, terminal panel, binding posts, and hand generator are of Signal Corps design and are used in other equipment. The remaining apparatus consists of standard commercial parts.
    b. The front equipment layout is shown in figure 4. The rear equipment layout is shown in figure 5. The operator's telephone circuit apparatus, dial cord circuit apparatus, and trunk circuit equipment are mounted on a plate running horizontally across the back of the switchboard just above the cord shelf. The capacitors can be removeq by first removing the guard under the equipment. The upper part of the switchboard is occupied by the jack and signal equipment. The line binding post panel is mounted in the top of the switchboard. The panel provides 90 binding posts in three parallel rows of 30 binding posts per row. These binding posts are arranged to screw down on the spade-terminal strips attached to the cables which connect to the panel BD-97. The binding post screws should be loosened or tightened only by means of a screw driver. The purpose of the binding post panel is to provide rapid means of connecting the line circuits to the panel BD-97* The binding posts are of a Signal Corps design and arranged to prevent the loss of the binding post screws.
    c. In subsequent discussions and manufacturer's drawings furnished with TC-4, frequent reference is made to the terms "tip" and "ring". A brief explanation of the meanings of these terms follows:
    15
    TM 11-332
    7-8
    Signal Corps
    The method of designating the two conductors, or sides of a line, as tip or ring is derived from the plug used on a magneto switchboard. One of the cord conductors is connected to the tip of the plug, and the other conductor connected to the ring of the plug. This method of distinction is applied to the line circuit. The tip of the plug makes contact with
    the short spring of the jack (see fig. 6). This jack spring is designated the tip spring and the side of the line connected to the tip spring is designated the tip side of the line, or tip conductor. The ring of the plug makes contact with a longer jack spring. This longer jack spring is designated the ring spring and the side of the line connected to the ring spring is designated the ring side of the line, or ring con
    ductor.
    x Insulating materia!
    7/	\\	'"Switchboard piua
    Cutoff confab "'Tip and ring springs
    SYMBOL —°r
    4—	*---I e „
    --*	T L - 10 74 A
    Figure 6. - Two conductors, plug and cut-off jack.
    d. Circuits. — The several circuits were designed for use in a magneto switchboard, and are explained in detail in the following paragraphs 8 to 16 inclusive.
    8. MAGNETO LINE CIRCUIT. - Reference figure 7. The circuit is for use with equipment that uses 16 to 20—cycle ringing current for signaling and may be used as a magneto trunk circuit in addition to being used as a magneto station line circuit. As direct current is not applied to the line through this circuit it cannot be used with telephones or circuits that require an external source of transmitter current (common battery telephones) or that require direct current for supervisory pur-
    16
    TM 11-332
    8-9
    Telephone Central Office Set TC-4
    poses. The application of a ringing current to this circuit from the line causes the drop to fall. When a plug is inserted into the jack, the drop is automatically restored by mechanical means and the winding of the drop is disconnected from the line at the cut-off contacts in the jacks. Contacts are provided on the drop to dose a night alarm circuit which provides, when desired, an audible signal when a drop falls. The magneto line circuit may be connected to the following types of equipment:
    a.	Military local battery (magneto) telephone such as telephones EE-3, EE-3-B, EE-4, EE-5, EE-8 and EE-8-A.
    b.	Commercial local battery (magneto) telephones.
    c.	Switchboards, as follows: Magneto line circuits in switchboards BD-14, BD-71, BD-72, BD-80-A, BD-89-A, BD-91, BD-96, and commercial magneto switchboards and common battery switchboards equipped with ring-down tie line equipment.
    200“or OSO” ro NI6H~
    O’ ----1	. ALARM
    p p I 4-{—CIRCUIT
    ~v~ _I_ (Answer)
    7-------------.T0---------n
    _____—a^u
    8/nd/OO flOs/s
    on /errms/	& 5'9no/
    pone/	n-3508
    Figure 7.	- Magneto line circuit.
    9. TRUNK CIRCUIT, DIAL AND COMMON BATTERY MANUAL. - a. Reference figure 4 (jacks in the middle group, top row) and figure 8 (schematic circuit diagram). This circuit is for use with common battery central office equipment of either manual or dial type. It may be connected in place of, or bridged across, ary dial telephone or ary common battery manual telephone.
    b. Working limit. - Supervision limit of central office to which connected, less 375 ohms in the trunk circuit.
    464872 0 - 42 -3
    17
    TM 11-332
    9
    Signal Corps
    Trunk Circuit
    , . Zte/ S Common Sa/Teru
    ™	Manua/
    (/.me)
    (0/a/)
    HI
    2pc
    Cka/
    (b)
    /X G.
    apt Supen/soryr~ iSyna/ |^i
    Jtfu
    —N^——
    TO NIGHT
    ---ALARM
    CIRCUIT
    _7o Trunk
    ■o /
    ZW Core/Oranf
    pane/
    rL-3509

    Figure 8.	- Trunk circuit and dial cord circuit.
    c,	. The application of a 16— to 2(A-cycle ringing current to this trunk circuit causes the drop to fall and connects ground to the night alarm lead to provide for an audible signal. (See figs. 8 to 13.) Insert an answering plug in the line jack (L) of the trunk circuit, which closes a circuit to bridge the coil of the drop across the line
    as a holding bridge. This action extends supervision to the central
    office and cuts off automatic ringing current if it is used.
    d.	On outgoing common battery manual trunk calls, insert the calling plug in the line jack (L) of the trunk circuit (see fig. 8a), which places the coil of the drop across the trunk, extending supervision to the central office without the necessity of ringing on the
    trunk.
    e.	On outgoing dial trunk (automatic) calls, insert the calling plug in the line jack (L), which connects the coil across the line, seizing the central office equipment. Insert the dial cord plug (see fig. 8b) in the dial jack (D) (see fig. 8a), which disconnects the drop coil from the trunk and closes a holding bridge for the trunk through the dial-impulse springs. Dial the desired number, which causes the
    18
    TM 11-332
    Telephone Central Officer Set TC-4	9-10
    switch train at the central office to complete the connection. After the dialing is completed, the dial cord is removed from the dial jack (D), and the trunk is again held through the drop coil.
    f.	When the plug is removed from the jack upon completion of a call, the trunk-holding bridge is opened signaling the central office operator in the case of a manual call or allowing the central office equipment to release in the case of a dial call.
    10. COHD CIRCUIT. - a. Reference figure 9. These cord circuits are limited to use with magneto lines, that is, at least one line to which the cord circuit is connected must use ringing current for recall and disconnect signals. Disconnect or recall signals are provided by a supervisory drop associated with each cord. These drops are located in the face of the switchboard.
    b.	When, on incoming calls, the plug of the answering cord is inserted in the line jack the supervisory signal is bridged across the tip and ring of the cord for ring-off supervision. The operator answers the call with the TALK-RING key in the TALK position.
    c.	On outgoing calls the plug of the calling cord is inserted into the line jack. Except when ringing, the TALK-RING key is operated to the TALK position until connection has been made to the called station. Upon operation of the key to the RING position, ringing current is applied to the line if the ringing machine is operating or the circuit is prepared for the operation of the hand generator.
    d.	When a conversation is completed, ringing current should be applied to the line by the telephone user or distant switchboard operator. The ringing current from the distant end of the line will operate the supervisory signal, thus providing a disconnect signal. When the common-battery trunk is used, ringing current for the operation of the supervisory signal must be supplied over the magneto line
    19
    IM 11-332
    10-11
    Signal Corps
    which has been involved in the trunk connection.
    e.	Operation of the TALK-RING key to t he TALK position connects the A and B leads together and completes the transmitter battery circuit of the operator’s telephone circuit. (See figures 9 and 11.)
    TO NIGHT / ALARM CIRCUIT Ho/fr R/ng
    (flnswefi  f’oa,er
    | 2__________<	4, ^4 R/ng/ng
    	6	GN-4/ TL -3511-------------Gepera/or
    Figure 10.	- Ringing circuit.
    20
    TM 11-332
    12
    LEXAS STAIE COLLEGE FUR WUMtft
    library
    Telephone Central Office Set TC-4
    To Cord Circuits . and 2d operators telep/ione circui t
    To Cord Circuit
    Grouping Terminals'
    , z	Binding -
    - posts on terminal pane/
    TZ o	11	/ Lead oprlav:
    m. o--------	/+
    First Operators	Q	Q
    „	telephone circuit
    n O--------- ---4-1	1——QZ
    Rt O-------> <-i rf -J 3	*
    j 1---------- a	^^£7=c-	rfcziz^
    ---- I key _ t----------------------------------
    a	~=r an
    d-O	r>	d/fdl r +
    „ „^X T7 ------------'	' CUack\	P
    -o —•W R
    3'Lead
    Coi/ C-/05
    wris/or
    ' Binding posts on terminal pane!
    (y/dst)
    t !	V
    Reg
    ~3V
    TL-3512

    Figure 11.	- First operator’s telephone circuit.
    12.	FIRST OPERATOR'S TELEPHONE CIRCUIT. - Reference figure 11. An anti-sidetone telephone circuit using induction coil C-105 is used in this switchboard. A varistor is bridged across the receiver terminals to reduce the acoustic shock to the operator caused by excessive voltages across the receiver terminals. The varistor consists of an arrangement of copper-oxide disks, the resistance of which decreases as the voltage increases, thus reducing the current through the receiver. A grouping key is provided so that through its operation the cords of this switchboard may be associated with the operator's circuit of an
    21
    TM 11-332
    12-14	Signal Corps
    adjacent switchboard at such times as this switchboard is unattended. The grouping key is mounted in the lower left-hand corner of the face equipment. Also provided in this location are keys for switching between transmitter batteries 1 and 2 and for switching to an external transmitter battery. The grouping terminals and external battery terminals are in the top of the switchboard. (See paragraph 5a for connections for grouping circuit.) Head and chest set HS-19 may be connected to the operator's telephone circuit by placing its plug PL-58 in the jack JK-37 located on the left front of the keyshelf.
    13.	SECOND OPERATOR'S TELEPHONE CIRCUIT. - Reference figure 12. This circuit provides for transferring the last four cord circuits to a second operator when traffic on the switchboard warrants. Term!nals for connecting a telephone EE-8-A or similar local battery telephone for the use of the second operator are located in the top of the switchboard. The key for transferring the cord circuits is located in the lower lefthand corner of the face equipment, and is marked: OPERATOR 1-2.
    To Cord C/'rcu/'r To Cord C7rou// Tcorafs /-Brno/.)	Tcore/s p-amc/.)
    'ft c	'R C
    '	771 o
    3/nd/ogr Pos/s
    OX? O 7~ art Xerfo/n O'/
    d? , C d-)} /-// Pane/
    To PrsX (poera/ors Cjor 2
    7e/eo/>or>e C/rao//
    Figure 12.	- Second operator's telephone circuit.
    14» NIGHT ALARM CIRCUIT. - Reference figure 13. This is a conventional night alarm circuit in which the operation of a drop signal completes a circuit from ground through the night alarm buzzer to negative battery, thereby giving an audible signal. The battery is normal ly in the
    22
    hi 11-332
    Telephone Central Office Set TC-4	14-15
    battery compartment in the back of the switchboard. Terminals for an external battery are in the top of the switchboard. When an external battery is used, no battery should be left in the compartment. The key which controls the operation of the night alarm is located in the upper
    left-hand corner of the face equipment and is marked:
    NIGHT ALARM OFF-
    CN.
    Night Alarm Circuit
    To Mag Line cct "3.-
    To Trunk cct ™______<
    To Cord cct. JA-----
    Buzzer	°
    -----------O2'
    ai/---	_ Txt. Bat
    M.A.3V.
    —
    —1—	B/nd/pg posts
    —	on Terminal
    pane/ TL-35>
    Figure 13.	- Night alarm circuit.
    Conference C/rco/A
    —.-;,n
    —ZZ^AO
    —ZZZZAD ,_ZZ^2AD ,_ZZXZAD ZzzEad
    TL-3515	Jacks
    FigUre 14. - Conference circuit.
    15.	CONFERENCE CIRCUIT. - Reference figure 14. This circuit con
    sists of six jacks wired in parallel for the purpose of connecting to
    gether a number of lines for conference purposes. Cord circuits or patching cords are used for connecting the various lines to the con-23
    TM 11-332
    15-17
    Signal Corps
    ference circuit. At the completion of a conference call, any party ringing-off causes all associated supervisory drops to fall,
    16.	MASTER SCHEMATIC DIAGRAM. - Figure 15 shows all schematic circuits encountered in switchboard BD-96. This figure will be of assistance in clarifying the relationship and interconnection between the various circuits.
    Trunk Circuital O/at & Common Battery
    Magneto L/ne Circuit	Cord Circuit	[HI-----	---
    Zt*	____/	Tb NACct
    r. c.	Wtp=°
    Cbfrfwce Oread X.	*■	*	£“~
    _ZX2A0 —	HITTW1 d,9h! A!arm C,reu,f
    —Ft^d	d	__
    ■---<—pO	Genera/nr To Trunk cd an_
    2d Operators	To Cord CCt _
    te/eptone set	-flead	*	---
    n____	? ? “rtzrEf	^7 L^r
    r' ------A?> I.I Bdoe/
    o--.kJJ	|___I I___	j------o->
    -ZVsZs on fernmo! fine/	I— . I S	4,„	['11^-1 dnv	"T“____ F N.A.3V
    I- _	X
    Atorma/ Operd/EX	oJ	-=- 31/	-=- w	~ on rekrnma/
    <$> IE.	«l T»	T-
    U -----------« ' T	r^,6
    Figure 15. - Switchboard BD-96, master schematic djagram,
    17* PANEL HD-97. - a. The arrangement of the apparatus is shown in figures 2 and 3« An opening with a sliding cover is provided for incoming line wires in each side of the panel. An opening with a sliding cover is also provided in the bottom of the upper cabinet for the cables
    24
    TM 11-332
    Telephone Central Office Set TC-4	17-18
    to the switchboard when the cabinet door is closed. Eight repeating coils C-161 are mounted four on each side of the protectors.
    b.	The cabling between the panel and the switchboard consists of three rubber jacketed cables each containing 1$ pairs of braidcovered latex insulated, No. 22 AWG standard conductors. The cables, exclusive of the cable connectors, are 21 feet in length. The cable is connected at the panel directly to the fuses. At the switchboard end the cables are terminated in cable connectors which consist of strips of insulating material between which is mounted a row of 30 spade terminals of Signal Corps design. The spade terminals are mounted so as to allow some movement so that they will be self-alining when connections are made to the binding posts on the switchboard terminal panel. The cable conductors are soldered to these spade terminals. The soldered connections are inclosed in a copper-alloy protecting cover.
    c.	Two vertical rows of 22 pairs of 1-ampere fuses and protector blocks (unit dischargers) are mounted in the panel. Two terminal strips, each with 44 binding posts of Signal Corps design, are mounted to each side of the panel for connecting the incoming line wires. These terminals are permanently wired to the line side of the fuses and protector blocks.
    18.	PCWER RINGER, 20-CYCLE. - a. a Telering or equivalent 20-cycle power ringer is provided in the lower cabinet of panel BD-97* The Telering may be used for a source of ringing power when 110-volt, 60-cycle a—c power is available. A cord for making the connection to the power outlet is wired to the power ringer* Another cord is provided for extending ringing current to the switchboard.
    b. The Telering 20-cycle power ringer is a vibrating reed type of frequency converter. The reed vibrates between a contact screw and an electromagnet. The contact screw is set at the factory, and it is
    25
    TM 11-332
    18	Signal Corps
    suggested that no change be made in the adjustment unless the reed vibrates in a surging manner or there is sparking at the contact. If sparking occurs, it requires only the slightest turn on the contact screw either inward or outward to correct it. However, it is seldom that any change will be necessary. The adjustment of the Telering contact is practically opposite to that of other vibrating type power ringers, in that the contact gap in the Telering must be kept as wide as possible. Closing the contact gap does not increase the output, but instead will upset the adjustment, causing sparking, interfere with radio reception, and may prevent starting. (See fig. 16.)
    TL-3517
    Contact Adjusting 1
    111111 Contact
    I Point
    Vibrating Peed
    Figure 16. - Telering 20-cycle power ringer, Cover removed showing vibrator assembly.
    26
    Elec tro ' Magnet-
    TM 11-332
    Telephone Central Office Set TC-4	19
    SECTION IV
    SERVICING AND REPAIR
    Paragraph Maintenance-------------------—--------------------------------- 19
    Packing for army transportation--------------------------------- 20
    19.	MAINTENANCE. - a. The greatest single factor in trouble-free operation is careful handling of the equipment while packing and unpacking, transporting and installing. Test all circuits after the installation has been completed. If the equipment is being kept in storage, test all circuits at least once each month, or more often where climatic conditions warrant. Inspect all fuses and protector blocks (unit dischargers) each time the circuits in the switchboard are tested.
    b.	Test the magneto line drops and the trunk drops for proper operation, on incoming calls, by ringing through several miles of field wire or through an artificial line composed of noninductive resistors. A suitable artificial line may be readily constructed from two resistors, one of 80-ohms resistance, and the other of 1000-ohms resistance. Connect the two resistors in series and use as a potentiometer. A telephone EE-8-A connected across the 1080-ohms resistance (the two resistors in series) may be used as a source of ringing power. Low potential testing voltage is obtained by making connection across the 80-ohm resistor. Connect the leads from the two ends of the 80-ohm resistor to the line terminals of the drop to be tested. The test may be made at the most convenient point. In case a line or trunk is connected to the drop undergoing test, open the line or trunk at the line terminals in panel BD-97. After completion of the test, reconnect the line or trunk.
    c.	In order to maintain high grade transmission through the cord circuits, clean all plugs as often as required to maintain brightness, using a light oil and cake rouge, or a paste type metal polish.
    27
    TM 11-332
    19-20	Signal Corps
    The use of light oil and cake rough is the more preferable method of polishing plugs, as there is less tendency to use an abnormally large amount of polishing material. It is also easier to remove the unused portion of the polishing material from the plug upon completion of polishing. Pour a few drops of oil on the cake or rouge, thereby soft-
    Figure 17. - Panel BD-97, cables secured for transportation.
    28
    TM 11-332
    Telephone Central Office Set TC-4	19-20
    ening the rouge to such an extent that when the polishing rag is rubbed across the surface of the cake, a small amount of rouge is transferred to the rag. Care must be taken when using either rouge or paste type of polish, to make sure that all surplus polishing material is thoroughly removed from the plug upon completion of the polishing operation.
    20.	PACKING FOR ARMY TRANSPORTATION. - Remove the spade-terminal strips from the switchboard and coil them and the associated cables with the ringing machine cords in the lower cabinet of the panel BD-97. (See fig. 17.) Close and fasten the upper cabinet doors. Reirove the legs from the panel and strap them on the sides with the cables and ringing power cords. Close the panel and fasten with the bars. (See fig. 18)
    Adjust the designation strips on the switchboard BD-90 to clamp the line and trunk drops in place. Remove the seat top from the switchboard cover pack the operator's head and chest set in tne cover, and fasten the cover in place on the switchboard. (See fig. 19.) The batteries should be removed to prevent corrosion of the svri.tchboard. Unclamp the switchboard from the base and turn upside down to facilitate packing the cords and
    29
    TL-3519
    Figure 18. - Panel BD-97 packed for transportation.
    Hi 11-332
    20
    Signal Corps
    TL'tfZO
    Figure 19. - Switchboard BD-96, front cover in place.
    cord weights in the switchboard. Turn the switchboard right side up
    and place the base over the switchboard. Carefully turn the switch
    board and base over and clamp the seat top in place. The switchboard
    may then be'returned to its proper position. (See fig. 20.)
    71.-3521
    Figure 20. - Switchboard BD-96 packed for transportation.
    30
    IM 11-332
    21
    Telephone Central Office Set TC-4
    SECTION V
    REPLACEMENT PARTS
    Paragraph
    List of parts------------------------------------------------ 21
    Addresses of manufacturers----------------------------------- 22
    21.	LIST OF PARTS. — The following list of major component parts is further expanded in succeeding subparagraphs dealing with the larger items of equipment.
    a. Telephone central office set TC-4> complete and composed of the following items;
    Stock No.	Name	Description	Ref.
    			Function	par;
    4C9996.6	Switchboard	BD-96	Switching	21b central
    4E3697	Panel	BD-97	Distributing 21£ and protector frame
    3A30	Battery-	BA-30	Furnish voice current
    3E2258	Cord	CO-258	Ground connection
    3E1451	Cord	CD-451	Ringing power
    5B4416	Ground rod	GP-16	Ground
    4B1279	Head and chest set	HS-19	Operator's set 21e
    4C5611	Maintenance equipment	ME-n	Storage for	21d spare parts and tools
    6Z751O-1	Paulin	Duck, type I 12.3 ft. by 16 ft.	Covering equipment
    4B5OO8	Telephone	EE-8-A, field portable.	, Auxiliary operator's set
    31
    TM 11-332
    21
    Signal Corps
    b._____________. -
    R0^‘ Flg* Cx i	~	Mfr^s Dwg. No.
    — No*_____Stock No,	Name__________Description______Function____Mfr._____Part No,	Signal Co,
    7	3Z297	Binding post TM-197	Line terminals	SC-D-4469
    7	UCU623C-1	Jack	and	Mounted 5 per	strip Magneto line	SCTM	D-3226	SC-D-4458
    Signal,	circuit	or W.E.Co. 23C	SC-D-4458
    Combined 8A 3Z297	Binding post TM-197	Trunk terminals	SC-D-4469
    Capacitor	1-jif	Blocking	W.E.Co.	141A	SC-D-4467
    8A	3DB2.39A	Capacitor	2-pf	((T), Blocking	SCTM	D-3246	SC-D-4467
    Q.	z za.	((R)	or W.E.Co. 139A	SC-D-4467
    oA	4C9996.6/D1	Drop	350-ohm	Trunk signal and	SCTM	D-3249	SC-D-4481
    Q.	i aaa z z /	holding bridge or W.E.C0. 34C	SC-D-4461
    8A	409996.6/JI	Jack	Cut-off	Dial	SCTM	D-3272	SC-D-4461
    8A	4C9996.6/J2	Jack	Circuit closing	Line	SCTM	D-32^0	SC-D-4461
    i	or W E Go
    8A	4C9996.6/R2	Resistor	25-ohm	Capacitor	SCTM	D-3232	SC—D-4467
    discharger	or A.E.Co. D-281867
    except 25-ohms
    8B	3DB2.39A	Capacitor	2-jif	Contact Prot.	SCTM	D-3246	SC-D-4467
    8B	3ES24K	Cord	5 ft,	2-cond.	Dial Cord cir-	SCTm"E*C°*	St-X	SC-D-4448
    cult
    8B 4B795	Dial	A.E.C0. Cat. #AK-41	A.E.Co. 24A36	SC-D-44S8
    8b 4C6248 Plug	pl-48	sc-d-4448
    SB	3Z5818AE	Resistor	600-ohm	Contact Prot.	W.E.Co.	18AE	SC-D-4467
    9	3ES24K	Cord	5 ft, 2-cond.	Cord circuit	SCTM	S-24-K	SC-D-4448
    9	409914.5/16 Drop	350-ohm	Cord supervisory SCTM	D-3227	SC-D-4458
    signal	or W.E.Co. 56B	SC-D-4458
    Switchboard BD-96
    TM 11-332
    21
    Telephone Central Office Set TC-4
    4C9996.6/KL Keys Lever type Talk-ring SCTM D-3229 SC-D-4463 . z , o or W.E.Co. C1W SC-D-4463 4C6248 Plug PL-48 Cord circuit W.E.Co. 47-A SC-D-4448
    10	6Z813	Base	Midget, flush	Ringing power Hubbell 7l|66	SC-D-4469
    cord
    10	4B456	Crank	GC-12	Gen. operation	SC-D-4448
    10	4B841	Generator	GN—41	Ring current
    Supply
    10	409996.6/K2 Key	Turn-button type Emergency SCTM D-3228	SC-D-4458
    or W.E.Co. 498M
    11	3Z239	Binding post TM-139	External Battery	SC-D-4469
    and Grouping
    terminals
    11	3DA25O-7	Capacitor	0.25-juf	Blocking	W.E.Co.	IhlD	SC-D-4467
    11	3DA50O-2O	Capacitor	0.50-fif	Blocking	W.E.Co.	141B	SC-D-4467
    11	3C1O5	Coil	C-105	Induction Coil	SC-D-4467
    11	404277	Jack	JK-37	Operator’s set	SC-D-4448
    11	409996.6/K2	Key	Turn-button	type	Battery 1-2,	SCTM	D-3228	SC-D-4458
    External Battery or W.E.Co. 498m	SC-D-4458
    Grouping
    11	4C9996.6/V1 Varistor	Receiver shunting Acoustic shock W.E.Co. 4A	SC-D-4467
    reduction
    12	3Z239	Binding post TM-139	Second operator's	sc-n-4469
    telephone terminals
    12	409996.6/K2	Key	Turn-button type Second operator SCTM D-3228	SC-D-4458
    or W.E.Co, 498m	SC-d-4458
    13	4C17O7B Buzzer	Night alarm W.E. Co. 7BW	SC-D-4466
    13	Key	Turn-button type Night alarm key SCTM D-3228	SC-D-4458
    or W.E.Co. 498m	SC-D-4458
    13	3Z239	Binding post TM-139	Night alarm	SC-D-4469
    external battery
    33
    TM 11-332
    21
    Signal Corps
    b. Switchboard BD-96. - cont'd
    ftef. Mg.	kfr’s. Dwg. ko.~
    No._____Stock No._Name_______Description_____Function___Mfr.___Part No. _
    14	4C4823A. Jack	Group mounted	Conference cir- SCTM 144	SC-D-4458
    cuit	or W.E.Co. 223	SC-D-4458
    4C9996.6/B3 Bolt, cabinet Cast brass	Cord weight Corbin 125	SC-D-4449
    door bolt
    6l6O5-1«5-1	Bolt	1-9/16 inch overall	SC-D-4449
    5/16 x 24 thread
    4C9996*6/B4 Bracket	Keyshelf, steel	SC-D-4463
    UC9996*6/B5 Bushing	Natural phenolic Generator mount-	SC-D-4475
    rod	ing insulator
    4C9996.6/C1 Case, battery Steel	SC-D-4448
    4C9996.6/B2 Door, back	With circuit label	SC-D-4449
    UC37O9	Fastener, cord Tinned brass	Cord terminal W.E.Co. 9	SC-D-4466
    4C9996.6/F2 Form	Laced	Line and trunk	SC-D-4479
    cable
    4C9996.6/F1 Form	Laced	Main cable	SC-D-4479
    409996.6/G2 Guard, dial Steel	SC-D-4475
    4C4247B Hook, cord 14 per strip	W.E.Co. 7B	SC-D-4466
    4C9996.6/G1	Insulator	Natural phenolic	Generator	base	SC-D-4475
    plate
    4C9996.6/L1	Leg assembly,	Leg, spring and	Support	SC-D-4477
    right	button assembly
    409996.6/L2	Leg assembly,	Leg, spring and	Support	SC-D-4477
    left	button assembly
    409996.6/L3 Lugs	Soldering	Used with TM-139 Cinch 1431	SC-D-4469
    409996*6/T2	Mounting	Jack and signal	Trunk circuit	SC-D-4458
    4C9996*6/N1 Nut, wing 5/16 inch, 24 thread	SC-D-4449
    4C9996.6/P6 Pad, felt	1-3/8" x 1-1/8" x	Continental 5888	SC-D-4470
    1A"
    U09996.6/P5 Pad, felt	12-1A" x 3" x 1A"	Continental 5888	SC-D-4470
    UC9996.6/P1 Pan	Steel	Equipment	SC-D-4449
    protection
    Telephone Central Office Set TC-4
    TH 11-332
    21
    35
    4C9996.6/R3 Plate,	Brass	SC-D-4458
    designation
    409996.6/P2	Plate,	XXX-black phenolic	Night alarm bus	SC-D-4458
    insulator	bar insulator
    409996.6/P4	Plate	Black phenolic	Keyshelf, right	SC-D-4463
    end
    Plate	Black phenolic	Keyshelf, left	SC-D-4463
    end
    4C9996.6/R1	Retainer	Steel	Supervisory	SC—D-4458
    drop retainer
    4C9996.6/S2	Screw	FEB, 1-9/16",	Keyshelf	SC-D-4463
    1/4 x 28 thread	retaining screw
    409996.6/S3	Screw	Oval head, 15/64"	Keyshelf bracket	SC-D-4463
    10-32 thread	screw
    409996. 6/S1 Seat assembly	SC-D-4446
    4C987O Strip,	5-3A inch	W.E.Co. 814	SC-D-4458
    designation
    4C9996.6/T1 Table assembly	SC-D-4446
    409996.6/12 Washer	Cupped, steel	Keyshelf retain-	SC-D-4463
    Ing screw washer
    409996.6/11	Washer	Soft rubber	Generator shaft	SC-D-4448
    dust protector
    4C9996.6/13	Washer	Insulating	Generator mounting	SC-D-4475
    4029100	Weight, cord	Flat, 8 to	11 ozs.	Cord return	SC-D-4448
    4028895	Webbing	Cotton	Cable damp	SC-D-4463
    TM 11-332
    21
    Signal Corps
    c. Panel BP-97♦ -Ref. Fig.	Mfr's. Dwg. No.
    No._______Stock No. Name___________Description________Function_____Mfr._______Part No. Signal C.
    3Z296	Binding	post	TM-196	Line and trunk	SC-D-Wi93
    terminals
    3C161	Coil	C-161	Repeating coil
    3E1427	Cord	CD-U27	Line aid trunk	SC-D-449f>
    connections to
    BD-96
    3Z21j32	Fuse	1-ampere	Sneak current	Cook	A-12
    protection
    11E682.1	Protector	Carbon (unit	High potential	Cook	2612
    block	discharger type)	protection
    Protector Mounting only,	Cook	10bO-H-51
    unit	less screws	modified
    and nuts UC9996.6/T3	Strip	Terminal	Line connection	sC-p-liliQ?
    . z z . ,	Gr 1
    uC999o.6/Tu	Strip	Terminal	Line connection	SC-D-)|)i92
    Gr 2
    4C9996.6/T5	Telering	110-volt	Power ringing	Telkor Model H
    machine
    I1C9996.6/SI1	Strap	Web	Securing
    CD-427 during transportation
    TM 11-332
    21
    Telephone Central Office Set TC-4
    d. Maintenance equipment ME-11. -Quantity---Stock No.__Name__________Description______Function_____Mfr._____Part No. Signai°C.
    10	3EL298/1-1 Angle	For connector of Spare	SC-D-4494
    cord CD-427
    1	6Z815	Base	Connector midget, Spare	Hubbell 7U66	SC-D-4469
    flush
    1?	3Z2?6	Binding post	TM-196	Spare	SC-D-4493
    12	3Z297	Binding post	TM-197	Spare	SC-D-4469
    7	1	Cap	Cord griP	Spare	Hubbell 975U
    1	6711	rhe8t +	SC-D-5091
    7	Connector	Power	Spare	Hubbell 7464
    1	3E2258 Cord	CO-258	Spare	SC-D-4271
    50 ft. 3E213O Cordage	Rubber covered, Spare	G.E.Co. 60 per-
    black, 2-conductor,	cent
    12	Ivo) 10	types
    X9	FU86	1-ampere	Spare	Cook A-12
    2	3Z3329 Ground rod GP-29	Spare	SC-D-4311
    1	AMtoA5	J?*’ ’Xedge 12 lb-	OOO-H-86
    1	6Z6096 Lamp, with 25-ft. long	G.E.Co. 9x282
    extension
    cord
    1	6Z69OQA Lantern	Electric, hand, Delta,
    with 2.4-volt miniature screw base lamp
    J PI>’	Lead» test	Weston D-7OO33-4
    1	6Z7496	Padlock	MC-96 type la-2
    ,	inch
    1	6R4513	Pliers	TL-13
    1	6R46O3	Fliers	TL-103
    1	6R4626	Fliers	TL-126
    4 dos. 6L6832-12.5 Screw	Machine RHB,	Spare repeating
    mickeled,	coil mounting
    3/4-inch, 8-32	screws
    TM 11-332
    21
    Signal Corp*
    d. Maintenance equipeent MR-11. - cant'd ~~~	~~ ~	—————————	Iffr's, Dwg. No.
    Quantity	Stock No.	Name___________Description_____Function______Mfr._____Part No. Signal 0.
    1	6R19100	Screw driver TL-128, consisting
    set	of the following:
    (Quantity in parenthesis)
    (1)	6R19O3O Screw driver Spiral ratchet	301
    (8)	6Q3U9OO	Drill	points	1/16" to	11/6U"
    and chuck
    (1)	6Q29230	Countersink
    (1)	6R19011	Screw	driver	Ratchet,	6-inch	n-6
    blade
    (1)	6R19O15	Screw	driver	Ratchet,	3-inch	1^.3
    blade
    1	6R2U$12H	Soldering	Size 1|, 3/U lb.,
    iron	with handle
    1	6R2U61?	Soldering	TL-ll?
    iron Soldering	Vulcan 2100
    iron holder
    1	3FUO65A	Test set	EB-65-A
    1	6R1i216?	Torch	TL-130
    12	UE682.1 Protector	Carbon (unit	Spare	Cook 2612
    block	discharger type)
    1	3FUO56a/V1 Volt-	Type 3C 0-100, 000 ohm,	Wfeston Model
    ohmmeter	0-300-600v d-c
    h doz. hBf>00U/lll Washer,	#8 SAE regular,	Spare,	for
    split,	nickel-plated	mounting respring	peating coils
    I4. doz.	Washer	#8 SAE regular,	Spare,	for
    nickel-plated	mounting re-
    peating coils
    1	6R55006 Wrench	TL-111
    	TM 11-332 Telephone Central Office Set TC-4	21-22
    e.	Head and chest set HS-19. -
    Stock No.	Name	Description
    4B41S	Chest unit	T-26, composed of the following iteae (Stock
    (4Z6924) (426925) (328118) 3E333 3E337 4C4153BA 4C4153BA/1 4B2358 4B2522	number in parenthesis): Strap	ST-24 Strap	ST-25 Switch	SW-118 Cord	CC-333,	6-foot, 3-eonductor Cord	CC-337,	20-inch, 2-conductor Headband Pad	Leather Plug	PL-58 Receiver	R-22
    f.	Switchboard plug cleaning material. Used with, but not in-
    eluded as a	part of telephone central office set TC-4.
    Stock No.	Name	Description
    6G1315 601516	Oil, light	3-ounce can (3-in-l) Polish, metal	Paste, 2-ounce box Rouge	Cake, jewelers'
    22. ADDRESSES OF MANUFACTURERS. -
    A. E. Go. Cinch Continental	Automatic Electric Co.	Chicago, Illinois Cinch Manufacturing Co.	Chicago, Illinois Continental Felt Co.	19th St. and Broadway, New York, N. Y.
    Cook Corbin G. E. Co. Hubbell SCTM	Cook Electric Co.	Chicago, Illinois P & F Corbin Co.	New Britain, Conn. General Electric Co.	Schenectady, N. Y. Harvey Hubbell, Inc.	Bridgeport, Conn. Stromber-Carlson Telep.	Rochester, N. Y. Mfg. Co.
    Telkor Vulcan W. E. Co. Weston	Telkor, Inc.	Elyria, Ohio Vulcan Electric Co.	Lynn, Mass. ‘Western Electric Co.	Chicago, Ill. Weston Electrical	Newark, N. J. Instrument Co.
    39
    Signal Corps
    TM 11-332
    (A. G. 062.11 (4-25-42	).)
    BY ORDER OF THE SECRETARY OF WAR:
    G. C. MARSHALL, Chief of Staff.
    OFFICIAL:
    J. A. ULIO,
    Major General,
    The Adjutant General.
    DISTRIBUTION:
    IBn 11 (2); IC 11 (10).
    (For explanation of symbols see FM 21-6.)
    40
    U. S. GOVERNMENT PRINTING OFFICE: 1942 O - 464872

    UNT LIBRARIES DENTON TX 78203
    ■IIIIHIMHI
    1001895973