    [Telephone Central Office Set Tc-2]
    [From the U.S. Government Publishing Office, www.gpo.gov]

    ﻿TM 11-340
    WAR DEPARTMENT
    TECHNICAL MANUAL
    TELEPHONE CENTRAL OFFICE SET TC-2
    October 19, 1942
    NON-CIRCULATING
    Document Reserve

    WU35; i|-34o
    TM 11-340
    rFXA5 STATE Cr>-__	*° 1
    TECHNICAL MANUAL WOwr6>
    TELEPHONE CENTRAL OFFICE SET TC-2
    Changes 1	WAR DEPARTMENT,
    No. 1 J	Washington 25, D. C., 12 November 1943.
    TM 11-340, 19 October 1942, is changed as follows:
    2.	Description.
    * * * * * * *
    Z>. Cabinet BE-79 (main distributing frame) (fig. 2).— (1) General.—Cabinet BE-79 is * * * at the switchboard. Twelve repeating coils C—161 are furnished as part of each cabinet BE-79. These coils are conveniently mounted on the line side of cabinet BE—79 to permit cross connection and cabling so that any repeating coil can be connected (between the central office side of the protectors and the switchboard cable terminals) into any incoming line as required to establish simplex or phantom circuits. (See par. 266.) Figure 2 shows repeating coils C-161 in place.
    (2) Equipment.—Cabinet BE-79 is equipped as follows:
    (a) Line side.—Protectors (protector blocks and heat coils) in two vertical verticals with 40 pairs per vertical. Total 80 pairs.
    * * * * * * *
    (-ton, 6x6, cargo.
    2.	Lay-out of equipment.—a. The arrangement of the equipment in Shelter HO-27-(&) (or HO-17-(&)) for one or two switchboards and main frames is shown in figures 38 and 39, respectively.
    b. Equipment which is fastened down is indicated by solid outlines; equipment not fastened down is indicated by dotted outlines. ' c. Unfastened equipment must be removed from the shelter before the set is put into operation.
    1 Shelters HO—17—(&) and HO—27—(&) are identical, except that shielding is provided in tho HO—17—(&) to reduce interference when the shelter is used to house a radio installation. Whenever available, Shelter HO-27-(&) should be used for the Telephone Central Office Set TC-2.
    579701°—44—AGO 176
    TM 11-340
    C 2	TECHNICAL MANUAL
    d.	Cording for the electrical connections is shown as heavy solid lines. The cording is numbered and cross-referenced in the table at the bottom of the figure. The table also lists the description of the cording and its terminal points.
    e.	Dimensions are given for preferred locations of fastened equipment and for their points of connection to the shelter.
    3. Fastening’.—The equipment may be fastened to the shelter by lag screws, toggle bolts, or bolts and nuts. The lag screws are easiest to install and remove. Lag screws, bolts, or toggle bolts should have a body dimension of %6 or % inch.
    4. Installation.—a. Fastened equipment.—The following procedure is used for fastening equipment to the shelter by either lag screws, bolts and nuts, or toggle bolts:
    (1) Use of lag screws (preferred means).— (a) Drill close-fitting clearance holes in the bases of the equipment to be fastened down in the locations shown in figure 38 or 39. Use a brace and auger bit (wood) or a twist drill.
    (Z>) Locate the equipment to be fastened down in the positions indicated in figure 38 or 39.
    (c) Drill lead holes in the shelter floor, using the clearance holes previously drilled in the bases of the equipment as a guide. Use a hand drill or electric drill with a %6-inch twist drill for %6-inch lag screws, or a ^-inch twist drill for %-inch lag screws.
    (d) Install flat washers and lockwashers under the lag screw heads to provide additional bearing area and to prevent loosening. A sufficient number of spacing washers should be installed under the screw heads when required, so that the lag screws will project approximately % to % inch through the shelter floor. Insert the lag screws in the clearance holes in the equipment and screw into the lead holes in the shelter floor with a wrench. Do not drive lag screws with a hammer.
    (2)	Use of bolts and nuts.— (a) Arrange the equipment in the shelter in accordance with the dimensions shown in figure 38 or 39.
    (b)	Elevate the shelter or otherwise provide working space beneath the floor of the shelter. Take all necessary precautions to permit personnel to work beneath the shelter in safety.
    (c)	After elevating the shelter, recheck the location of the equipment to be certain that it has not moved. Relocate the equipment if necessary.
    2
    AGO 176
    TM 11-340
    C 2
    TELEPHONE SET TC-2
    (d)	Drill bolt clearance holes in the locations specified in figure 38 or 39. Use a twist drill for making these holes.
    (e)	Install sufficient flat washers under the bolt heads so that the bolts will not project below the bottom of the shelter skids; then insert the bolts in the clearance holes. Install flat washers, lock washers, and nuts. Tighten the nuts, using wrenches on both the nuts and the bolt heads.
    (/) Lower the shelter to the ground or relocate it in the body of the truck.
    (3)	Use of toggle bolts.—(a) Arrange the equipment to be fastened in accordance with the dimensions shown in figure 38 or 39.
    (6) Use a twist drill to drill clearance holes in the equipment and floor of the shelter, in the locations shown in figure 38 or 39.
    (c) Insert the toggle bolts in the clearance holes. Install flat washers and lockwashers under the nuts and tighten the nuts with a wrench.
    b. Cording.—(1) Install the cording in the locations shown in figure 38 or 39.
    (2)	Cut a hole in the rear-end wall of the shelter at the location shown in figure 38 or 39 to accommodate Cords CD-393 and CD-409. The dimensions of the hole should be the minimum size required for the cords.
    (3)	Cut a hole of the minimum size required in the locations shown in figures 38 or 39 to accommodate ground Cord CO-258.
    (4)	To make the shelter weatherproof and to keep light in, place canvas squares over the cord holes in the shelter rear-end wall. Fasten the squares by their top edges to the outside of the shelter wall.
    e. Communication lines.—(1) Cut the holes for the communication lines in the shelter side wall in the locations shown in figure 38 or 39. Make the holes 3 inches in diameter and locate them above troop-seat height.
    (2) Install a square of canvas over the communication-line hole at the top edge on the outside of the shelter wall to provide weatherproofing and lightproofing.
    (3) At an operating point, bring the communication wires and cables through the hole and terminate them directly on the main distributing-frame terminal blocks.
    3
    AGO 176
    TM 11-340
    c 2
    TECHNICAL MANUAL
    d. Cabinet BE-70-(<&) (wire chiefs test set).—(1) When only-one main distributing frame is included in the installation, construct a wooden shelf of the required size and install Cabinet BE—70—(&) on the shelter wall adjacent to Cabinet BE-79-(&). When two Cabinets BE-79 are included in the installation, shape two pieces of strap iron to form a cradle for suspending the Cabinet BE-70-(&) between the two main distributing frames at the operating point.
    (2) When not in use, keep the Cabinet BE-70-(&) in Case CS-57 to protect against damage. If Case CS-57 interferes with the operation or maintenance of the central offices at operating points, it may be removed from the shelter.
    e. Unfastened equipment.—When only one switchboard and main distributing frame is included in Telephone Central Office Set TC-2, locate the unfastened components in Shelter HO-17-(&) or HO-27- (&), as shown by the dotted outlines in figure 38. If two switchboards and main distributing frames are included in Telephone Central Office Set TC-2, a trailer, 1-ton, two-wheel, cargo, is required for the unfastened components. These components are located in the trailer in the positions shown in figure 40.
    5. Material list.—The material required for mounting Telephone Central Office Set TC-2 in Shelter HO-17-(&) or HO-27-(&) is given in the following table. (Equivalent bolts and toggle bolts may be used (if available) instead of the lag screws listed.)
    				Number required for—
    Signal Corps stock number			Name and description	1 switchboard and 1 main frame	2 switchboards and 2 main frames
    3Z7700-17(&)	1 or	> 3Z7700~27(&)	1 5B1006-3*—		 ci	 5B 20080....		 6L71006..					jShelter H0-17-(&)„.	 [Shelter H0-27-(&)—	 Screw, lag, G. I., x 3"			 Screw, lag, G. I., x 2M"	 Screw, lag, G. I., 56" x 2M"	 Washer PE-80, round; G. I.		 Lockwasher, steel						1 1 16 4 6 40 28	1 1 20 8 6 50 36
    •Lag screw Me inch in diameter may be substituted.
    4
    AGO 176
    TM 11-340
    C 2
    TELEPHONE SET TC-2
    APPROX. 65 TELEPHONE LINES
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    // TV M-205	SWITCHBOARD BD-89 —■£ —	'P«^O Igfl ’ I ’	I 'S
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    7	/$y	\ s. LT	ME-6-(CH-59) -J41I1__A5 MAINTENANCE EQUIPMENT J I (/ ^XZ>X	/
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    . . ...	TO H0VA.C.
    V-CASE CS-63	TL_748|
    Figure 38.—Telephone Central Office Set TC-2, including one switchboard and one main distributing frame, mounted for operation in Shelter H0-17-(&)
    . or HO-27-(&).
    5
    AGO 376
    TM 11-340 C 2
    Key to figure 38.
    TECHNICAL MANUAL
    WIRING IDENTIFICATION TABLE
    Number on drawing	Description	Connects—
    1, 2, 3.					Cord CD-298 (part of BE-79)						BE-79 to BD-89 BE-79 to GP-29 BD-98 to BE-79 BB-46 to BD-98 BD-89 to BD-98 BD-89 to BD-98 PE-75 to BE-75 BE-75 to a-c power BE-75 to BD-89
    4..1				Cord CO-258.."
    4				Part of BD-98
    5....					Cord CD-335
    6				Part of JB-19
    7....				Part of JB-19
    8			Cord CD-409
    9.						Cord CD-393
    10			Cord CD-395,

    Notes.—1. A and B designate locations of the equipment clearance holes and the shelter floor lead holes, used for holding the lag screws for fastening. Do not drill clearance holes in the shelter floor unless bolts or toggle bolts are to be used for fastening.
    2. B designates clearance holes drilled in back-cover slots of Switchboard BD-89. The back cover should be notched at lower comers to clear lag screw heads.
    Key to figure 39.
    WIRING IDENTIFICATION TABLE
    Number on drawing	Description	Connects-—
    1, 2, 3				Cord CD-298 (part of BE-79)		BE-79 to BD-89
    11, 22, 33		Cord CD-298 (part of BE-79)					BE-79 to BD-89
    4				Cord CO-258					BE-79 to GP-29
    4A ...					Cord CO-259 					BE-79 to BE-79
    4B				Part of BD-98 (ground)				BE-98 to BE-79
    5 			Cord CD-335			BB-46 to BD-98
    6....					Part of JB-19						BD-89 to BD-98
    7....					Part of JB-19					BD-89 to BD-98
    8....					Cord CD-409		PE-75 to BE-75
    9.			Cord CD-393			BE-75 to a-c power
    10				Cord CD-395				BE-75 to BD-89
    10A .....				Cord CD-394 (a-c power)		BD-89 to BD-89

    Notes.—1. A and B designate locations of the equipment clearance holes and the shelter floor lead holes, used for holding the lag screws for fastening. Do not drill clearance holes in the shelter floor unless bolts or toggle bolts are to be used for fastening.
    2. 13 designates clearance holes drilled in back-cover slots of Switchboard BD-89. The back cover should be notched at lower corners to clear lag screw heads.
    6
    AGO 176
    TM 11-340
    TELEPHONE SET TC-2	0 2
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    O 4/______________—n	L lx Ml
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    APPROX. APPROX.
    65 TP 65 TP
    LINES LINES
    Figure 39.—Telephone Central Office Set TC-2, including two switchboards and two main distributing rrames, mounted for operation in Shelter H0-17-(&) or HO-27-C&).
    7
    AGO 170
    TM 11-340
    C 2
    TECHNICAL MANUAL
    l
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    ■	CASE* C’W2^	‘
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    Figueb 40.—Arrangement in trailer of unfastened equipment when two-position Telephone Central Office Set TC-2 is installed in Shelter HO-17,	>
    [A. G. 300.7 (10 Mar 44).]
    By order of the Secretary of War :
    Official :
    G. C. MARSHALL-
    Chief of Staff.
    J. A. ULIO,
    Major General, The Adjutant General.
    Distribution :	;
    Armies (2); Corps (2); Sv C (1) ; Depots (1); Def iComds (1); D (2); IBn 11 (2); IC 11 (10); Sig C Sch (50).
    IBn 11: T/O 11-15, Sig Bn.
    IC 11: T/O 11-88-S, Sig Co Opn Wire Armd; 11-267, Sig Co AAF; 11-217, Sig Co Avn; 11-287, Sig Co Dep Avn; 11-18; Field Opn Co, Sig Bn; 11-460-15, Sig Hqs Co, AWS Fi Comd; 11-107, Sig Dep Co; 11-127, Sig Rep Co; 11-327, Sig Port Sv Co; 11-587, Sig Base Maint Co.
    For explanation of symbols see FM 21-6.
    AGO 176
    U.5.GOVERNMENT PRINTING OFFICE: 1944
    8
    TM 11-340
    TECHNICAL MANUAL No. 11-340
    WAR DEPARTMENT Washington, October 19, 1942.
    TELEPHONE CENTRAL OFFICE SET TC-2
    Section I. General.	Paragraph
    Use ....................  ................   1
    Description .............................    2
    H. Employment.
    Equipment layout ________________________    3
    Setting up and connecting equipment_______	4
    Switchboard operation ____________________   5
    Rectifier RA-36-A, B, or C _______________ 6
    Cabinet BE-70-B..........................    7
    III. Detailed functioning of parts.
    Switchboard BD-89-A .....................    8
    Magneto line circuit _____________________ 9
    Common-battery line circuit ______________  10
    Outgoing line circuit _____________________ 11
    Through line circuit ______________________ 12
    Trunk circuit, two-way for connection to dial ■ (automatic) telephone central office and associated dial cord circuit ______________ 13
    Trunk circuit, two-way to manual commonbattery telephone central office __________ 14
    Universal cord circuit _____________________ 15
    Ringing circuit __________________________ 16
    Operator’s telephone circuit and grouping key circuit...............................      17
    Conference jack circuit___________________ 18
    Switchboard test circuit _________________ 19
    Night alarm circuit ______________________ 20
    Fuse alarm circuit __________________...,_ 21
    Battery and ground circuit, 24 volts ___ .... 22
    Power and heating circuit, 110-120 volts, alternating current _______________________ 23
    Cable connector circuit___________________ 24
    ♦This manual supersedes TM 11-340, November 1, 1941.
    1
    TM11-340
    1
    SIGNAL CORPS
    Working limits, general explanation________ 25
    Cabinet BE-79 _____________________________ 26
    Power equipment ___________'_______________ 27
    Storage battery _______'___________________ 28
    Power panel________________________________ 29
    Cabinet BE-75 _________.___________________ 30
    Panel BD-98 _______________________________ 31
    Telering 20-cycle power ringer,	Model	H ___ 32
    No. 84F interrupter_____________________ .. 33
    Power supply ______________________________ 34
    Rectifier RA-36-A, B, or C	35
    Line test equipment—cabinet BE-70-B	36
    IV. Servicing and repair.
    Maintenance ____________________________ 37
    Alarm type fuses _____________________ .. 38
    Storage batteries	_____ 39
    Switchboard plugs, cleaning _____ ....	40
    Manufacturer’s drawings	41
    Relay adjustment data ___________ ....	42
    Packing for army transportation .... .	43
    V. Replaceable parts.
    List of replaceable parts _________________ 44
    Addresses of manufacturers ________________ 45
    Section I
    GENERAL
    Paragraph
    Use ..................................................... ... 1
    Description ...................................            2
    1. Use.—a. General.—Switching central, telephone central office set TC-2, is for use at an army corps or other headquarters which requires a telephone switchboard of the capacity of one or two switchboards BD-89-A as described in paragraph 2a. The total weight of the complete equipment is approximately 2,900 pounds.
    2
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 1-2
    b. Component parts.—
    [Quantity!	Article	Approximate size	Approximate weight in pounds
    2	Batterv BB-46				1 C 1 if v A 1 M-v-1/1 O /1 A M
    1	Cabinet BE-70-B (wire chief’s test set). 							Jjj'x 0 -j xi 4 y/io 	 12" x Q"x1R"	32
    1	Cabinet BE-7S (a-c power distribution)				1 3 1 "y 4. 5/8 "y 0 2 3 "	25
    1	Cabinet BE-79 (main distributing frame)							26" x20"x413"	300
    1	Case CS-57 (for BE-70-B)						1 51 "y 1 51 "v99 3 "	36
    2	Case CS-63 Tor BB-46)		90 1 "y 8 5 /g "y 90 "
    1	Case CS- 70 (for M-205)					22 1 "X221 "x^6"	67
    1	Case CS-71 (for BD-98).					30 " y 9 «1 "y9 01 "	110
    1	Case CS-72 (for FM-31, HM-5, and 3 GP-29). 							20" x!0i"x39|".			50
    1	Case CS-73 (for RA-36-A, B, or C, BE-75, and FM-30).....	26|"x28f"x24 j"	63
    1	■Chair M-205			 				22
    1	Cord CD-335 (BB-46 to BD-98). . ............................ ..........		13
    1	Cord CD-393 (a-c power to BE-75;								20
    1	Cord CD-394 (a-c power; BD-89 to BD-89)				8 ' long	5
    1	Ccrd CD-395 (BE-75 to BD-89-A)				10
    1	Cord CD-409 (PE-75-A, B, or C to BE-75) ..... .	.50 ' long	20
    1	Cord CO-38 (BB-46 to BB-46;						 			1 /16
    1	Cord CO-258 (BE-79 to GP-29)					4
    1	Cord CO-259 (ground lead, BE-79 to BE-79)				5 ' long	2
    3	Ground rod GP-29
    1	Hammer HM-5.	  1						36" long		12
    2	Head and chest set HS-19—							Packed in switchboard		1} each
    1	Junction box JB-l 9	 ... .	... .	10 -1-fr y 4"y 53"
    		with 2—30 ' cables		17
    1	Maintenance equipment ME-6 (CH-59)		39" x21"x30"	250
    1	Panel BD-98 (power)						24|"x26"x26)"	145
    2	Paulin, duck, type I, equipped with not less than 10 grom-
    	mets with 5 J ' cotton tie ropes 					12 3 'xl6 '
    1	Power unit PE-75-A, B, or C				25|"x24j"x32".		275
    1	Rack FM-30 (for RA-36-A, B, or C and BE-75).	24" xl6f"x20|"	50
    1	Rack FM-31 (for BB-46)				16" xl6" x 3"	7
    1	Rectifier RA-36-A, B, or C							21" xl6)"x20"	75
    1	Switchboard BD-89-A			22J"x35i"x47}"	400
    1	Tool equipment TE-44-A.	      |	34f xl8i"x26|"				50
    2. Description.—a. Switchboard BD-89-A (fig. 1).—(1) General. —Switchboard BD-89-A is a complete, portable, single-position,
    two-panel, manually operated telephone switchboard for serving both magneto and common-battery lines, and is arranged for handling both types of local calls as well as originating and terminating trunk and tie-line traffic. Universal cord circuits are employed. Lamp signals are provided for the common-battery lines and the cord circuits. Drop signals are provided for the magneto lines, with magneto recall lamps associated with each cord. The line jacks are wired to a binding post panel at the rear of the switchboard which provides for connections with spade-terminal
    3
    TM11-340
    2
    SIGNAL CORPS
    strips through rubber-jacketed cable to cabinet BE-79 (main distributing frame). Terminal facilities are provided for making connections to the exchange battery, ringing current, and grouping key circuit.
    (2) Circuits.—Each switchboard contains the following circuits:
    Quantity
    Type of Circuit
    1 Operator’s telephone circuit with grouping key
    13	Universal cord circuits
    1	Ringing circuit
    20	Line circuits, magneto	(drop	and	jack)
    37	Line circuits, common-battery	(lamp	and jack)
    1 Trunk circuit, two-way to dial (automatic telephone central office)
    1 Dial cord circuit
    2 Trunk circuits, two-way to common-battery manual telephone central office
    3	Line circuits, outgoing
    2	Line circuits, through
    1 Conference circuit (5 jacks)
    1	Switchboard test circuit
    1	Night alarm circuit
    1	Fuse alarm circuit
    1 Battery and ground circuit, 24 volts
    1 Power and heating circuit
    (3) Jack numbering.—The jack equipment on the face of switchboard BD-89-A is divided generally into two panels of five jack mounting strips each.
    (a)	Magneto line jacks.—The magneto line jacks and drop signals appear in the two bottom jack mounting strips in each panel, and ' are of the mechanically restored, combined jack and signal type, mounted five per strip. The lines are numbered consecutively from 0 to 19, starting from the lower jack strip in the left-hand panel. Jacks are numbered from left to right; thus the lines appearing in the bottom jack strips of the left-hand and right-hand panels are numbered from 0 to 4 and 5 to 9, respectively. Lines 10 to 19 appear in the second row of jack strips, counting from the bottom.
    (b)	Third jack strip, left-hand panel.—The first jack is the dial jack for the dial trunk (which appears in the fourth jack strip from the bottom, and immediately above the dial jack). The second and third jacks from the left-hand end are the A and B jacks, respectively, of the first through line circuit (par. 12). The fourth
    4
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 2
    and fifth jacks are, respectively, jacks A and B of the second through line circuit. The last five jacks in this jack strip are the conference jacks A, B, C, D, and E, respectively (par. 18).
    (c)	Third jack strip, right-hand panel.—The first seven jacks, counting from the left of the jack strip, are the jacks of the switchboard test circuit (par. 19), A, B, C, D, E, F, and G, respectively. The three remaining jacks on the right-hand end of the jack strip are the jacks associated with outgoing line circuits (par. 11) 1 to 3, inclusive.
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    i ISfc—
    111 1111 11111 (OuiH ° (T~——-\	'i']	/^~^\ °
    I dm jj-i ,.|^a Ov 1'1 l||	'•» o"'"^ - 9 3
    i j | W \
    11 '*!! i S111
    'i'l H '
    Hi! il I |
    ihii;1 ! iij l
    lilll'l ! I
    I I HI
    I I
    Nl I ®	|^J
    IIht	_ — ...
    ------------- TL-3922
    Figure 1.—Switchboard BD-89-A, front view, cover removed.
    5
    TM11-340
    2	SIGNAL CORPS
    (d)	Fourth jack strip, left-hand panel.—The first jack is the dial trunk answer jack (par. 13) and is numbered 0 (zero). The second and third jacks are the two manual trunk answer jacks (par. 14) and are numbered 1 and 2. The remaining seven jacks are commonbattery line jacks (par. 10) and are numbered from 3 to 9, inclusive.
    (e)	Fourth jack strip, right-hand panel.—This jack strip contains the jacks associated with common-battery line circuits numbered 10 to 19, inclusive.
    (f)	Fifth row of jack strips.—Common-battery line circuits 20 to 29 appear in the jacks in the left-hand panel, and circuits 30 to 39 appear in the right-hand panel.
    (4) Case.—The case of switchboard BD-89-A is of trunk type construction, making a separate packing case unnecessary for army transportation.
    b. Cabinet BE-79 (main distributing frame) (fig. 2).—(1) General.—Cabinet BE-79 is a main distributing frame unit for use with one switchboard BD-89-A. It is equipped with protector blocks and heat coils which are connected to terminal strips. Binding posts TM-197 are provided for the incoming lines and for cross-connecting, so that all such connections can be made in the field without soldering The connections from cabinet BE-79 to switchboard BD-89-A are made with rubber-jacketed cables (cord CD-298) equipped with binding post cable connectors (terminal strips) at the cabinet, and spade-terminal cable connectors (terminal strips) at the switchboard. Provision is made for mounting and crossconnecting repeating coils C-161 (not furnished as part of the TC-2). Figure 2 shows repeating coils C-161 in place.
    (2)	Equipment.—Cabinet BE-79 is equipped as follows:
    (a)	Line side.—Protectors (protector blocks and heat coils in two vertical with 40 pairs per vertical). Total 80 pairs.
    (b)	Switchboard side.—Terminals connected to switchboard. (Three verticals of 25 pairs per vertical.) Total 75 pairs.
    (c)	Coil rack.—Capacity for 12 coils C-161. These coils are not furnished as part of cabinet BE-79.
    (3)	Terminal numbering.—The cross-connecting terminals on the switchboard side of cabinet BE-79 are mounted in three verticals. The circuits appearing on each vertical are as fchows:
    (a)	Left-hand vertical.—The 20 magneto line circuits appear on the top 20 pairs of binding posts and are numbered from 0 to 19, in descending order. The 10 terminals associated with through line circuit No. 1 appear immediately below the magneto line
    6
    11-340
    2
    TELEPHONE
    TM
    CENTRAL OFFICE SET TC-2
    ~	TL-415f
    Figure 2.—Cabinet BE-79, line side, showing repeating coils in place.
    TM11-340
    2
    SIGNAL CORPS
    terminals. The terminal designations of each binding post associated with the through line circuit are stenciled on the binding post panel opposite the corresponding binding post. See paragraph 4 |iii|
    aAWwMA" ®/a\ TwEA Nt AJUw A\ xffllLx yVvMj^l RA \ A „ AJA__________________________________________PART or
    \\\ / 6 ra'36’° \\\ o*n	\
    \IW9 A is:;; \X	u? ? w A
    \	\	UJ ° |\\ s'
    ^V\T	% \ ’» <>	HIP u \
    C>VTSF A \ W%	| , U> S
    \ J \ VrW .LAa^c J PACKING DATA_________ \	~"AjX	■Xi	.S
    CASE FOR EQUIPMENT	\ °'		O>	fvK AH tA\
    --------------------------?	cWl J kAr o
    V
    IJ	TL-4IS3
    V Figure 5.—Cording diagram, TC-2.
    (2) Install the 24-volt battery group (2 batteries BB-46), power unit PE-75-A, B, or C, and panel BD-98 in the selected location. See figure 5 for method of assembling case CS-71, panel BD-98, and rack FM-30 (containing rectifier RA-36-A, B, or C, and cabinet BE-75) into one unit. Install the three ground rods GP-29. Connect cord CO-258 from cabinet BE-79 to ground rods GP-29, and the
    12
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 4
    ground lead (GR) from cabinet BE-79 to the ground terminal on panel BD-98. Connect cord CD-395 from switchboard BD-89-A to cabinet BE-75. Connect the switchboard battery cable and ringing cable from junction box JB-19 to panel BD-98. Connect the two batteries BB-46 in series with cord CO-38, and connect cord CD-335 from the two batteries BB-46 to panel BD-98. Plug the Telering power-ringer cord into cabinet BE-75 and cords from rectifier RA-36-A, B, or C to cabinet BE-75 and panel BD-98, respectively. Connect cabinet BE-75 to the 110-120-volt a-c power supply with cord CD-393, or if an independent source of a-c power is not available, connect panel BD-98 to power unit PE-75-A, B, or C with cord CD-409 after the power unit has been checked for proper operation (refer to TM 11-900 or TM 11-901 covering the power unit). Test the operation of all power equipment. If the charging equipment causes objectionable noise on the telephone lines, two banks of batteries will be required, one bank being charged while the other is in use. See paragraph 6 for operating instructions for rectifier RA-36-A, B, or C.
    d.	Insert fuses in the fuse mountings on the rear of switchboard BD-89-A, if not already in place. Plug in the operator’s head and chest set HS-19. Test the operation of all circuits. See section III for detailed descriptions of the various circuits. Check line and trunk designation strips and make changes as required.
    e.	Install and test cabinet BE-70-B, wire chief’s testing cabinet (see par. 7).
    /. When a second switchboard BD-89-A and its associated cabinet BE-79 are required, install them as indicated in figure 5. Supply a-c power to the second switchboard BD-89-A from the first switchboard BD-89-A by means of cord CD-394. Connect the battery and ringing current cord of the second switchboard to junction box JB-19 of the first switchboard. Extend ground from the frame of the first cabinet BE-79 to the second cabinet BE-79 by means of cord CO-259.
    g. If a through line circuit (par. 12) is desired, cross-connect the jacks as follows: Binding posts designated Tl, Rl, and 8 associated with jack A should be cross-connected to similarly designated binding posts associated with jack B. The T and R terminals of jack A are now associated with the T and R terminals of jack B through the cut-off springs of the respective jacks.
    13
    TM 11-340
    5	SIGNAL CORPS
    5. Switchboard operation.—The operation of the switchboard is characteristic of comparable commercial practice.
    a.	Incoming calls.—A drop signal indicates a call on a magneto line. A line lamp (located below the line jack) indicates a call on a common-battery line or trunk.
    b.	Answering calls.—To answer a call, insert the answering (back) plug in the jack associated with the signal, and operate the TALK-RING key (in front of, and in line with the plug being used) to the locking TALK position (away from the operator) to connect the operator to the circuit.
    c.	Outgoing calls.— (1) Calls to station line.—To call a station, insert the calling (front) plug in the desired party’s line jack and operate the TALK-RING key to the non-locking RING position (toward the operator).
    (2)	Trunk calls to dial exchange.—To connect a telephone to a dial exchange for the purpose of making an outgoing call, proceed as follows: Insert the calling (front) cord plug in the LINE jack of the dial trunk. Wait for dial tone. When dial tone is heard, plug the dial cord plug into the DIAL jack and dial the desired number. Remove the dial cord plug at once and listen for the ringing tone.
    (3)	Trunk calls to common-battery manual exchange..—Connect the calling (front) cord plug to the manual trunk jack. The act of inserting the plug into the manual trunk jack signals the distant manual operator.
    d.	Supervision.— (1) Common-battery circuits.—Supervision on common-battery circuits is provided by a double row of lamp signals located on the keyshelf between the row of keys and the plugs. The lamp signals in the front row are associated with the front cords, and the lamps in the back row are associated with the back cords. To assist in identification of corresponding cords and lamps, the colors of the various lamp caps are the same color as their associated cords, alternate red, white, and green. Double supervision is thus provided. A lighted supervisory lamp indicates that either the calling or called party (depending on which lamp is lighted) has not answered or has disconnected. Intermittent up and down movement of the telephone receiver switchhook on a commonbattery circuit causes the cord supervisory lamp to flash. Upon receiving such a flashing signal, the operator challenges on the line by operating the TALK key associated with the flashing lamp, and
    14
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 5
    requests the wishes of the telephone user. Care must be used in supervising trunk calls to or from a manual common-battery exchange and in disconnecting promptly, since the operator at that exchange normally depends upon receiving a disconnect signal from the trunk to switchboard BD-89-A before completing disconnection in the manual central office.
    (2) Magneto circuits.—Each magneto circuit supervisory lamp is located on the face of the board directly above the associated plugs. Ring-off or recall (the signal sent to the operator when either party operates his ringing generator after completion of a call) is indicated by a lighted lamp which remains lighted only during the ringing period. Upon observing a lighted recall lamp, the operator challenges on the line before taking down the cords to determine whether the signal means disconnect or recall.
    e.	Grouping key.—By operating the grouping key (engraved GR) on the keyshelf, the cords of this switchboard may be used by an operator at an adjacent switchboard during periods of light traffic, when it is not necessary that this switchboard position be attended.
    /. Night alarm key.—The night alarm circuit may be disconnected by operating the night alarm key (engraved NA) on the face of the switchboard to the OFF position. Operate the night alarm release key (engraved NA RLS) on the keyshelf after each actuation of the night alarm circuit caused by the lighting of a commonbattery line lamp, in order to release the alarm and prepare the circuit for the next signal.
    g. Monitoring key.—To monitor (listen) on a circuit, first operate the monitoring key (engraved MON), and then operate the TALK key associated with the cord circuit used. The operator cannot talk on the line being monitored but can listen in to determine whether or not the line is in use. The monitoring key connects the operator’s receiver across the line without introducing any perceptible loss in transmission.
    h. Conference circuit.—The conference circuit is used to connect a number of lines together as follows: Insert an answering (rear) cord plug in the jack associated with the telephone of the person originating the conference. Then insert the associated calling (front) cord plug in a conference-circuit jack. The conference is completed by inserting the answering cord plugs in other jacks of the conference circuit and calling the desired telephones with the respective calling cords. Patching cords may also be used in conference connections under certain conditions (see par. 18b).
    15
    TM11-340
    6
    SIGNAL CORPS
    6. Rectifier RA-36-A, B, or C.—a. Installation.—Care should be exercised when removing rectifier RA-36-A, B, or C from case CS-73, to avoid damaging the equipment and meters. Mount the rectifier on frame FM-30 and fasten it securely. Before making any electrical connections, be sure that the a-c circuit to which the rectifier is to be connected agrees with the voltage and frequency stamped on the name plate. If there is any doubt about the voltage and frequency of a commercial source of a-c power, consult the local power company for information. Connect the movable primary lead (fig. 4) to the voltage tap, on the primary terminal board, that is nearest the value of the actual line voltage. Install the two rectifier tubes, if these have been packed separately, and attach the connecting leads with clips to the wires at the top of the tubes. The two rectifier tubes must be firmly screwed into their respective sockets.
    b. Connections.—(1) Before connection is made to the storage ' batteries, turn the control switch to the OFF position and remove all four adjustment plugs, in order to prevent damage to the rectifier in case the two leads to the battery should accidentally become shorted prior to actual connection to the battery, and to avoid accidentally overloading the rectifier when the batteries are first connected.
    (2) The two negative ( —) leads have been connected together and wired through a cable to power panel BD-98. This cable is part of rectifier RA-36-A, B, or C.
    (3) The positive ( + ) lead has been wired through a reactance, then through the cable to power panel BD-98. The reactance is used as a noise filter to prevent electrical noise from the rectifier from reaching the storage battery, and thence into the talking circuits.
    c. Operation.— (1) In order to get the most efficient operation from the rectifier, place the coarse adjustment plugs in correspondingly numbered holes on the right and left control panels (fig. 4). Likewise place the fine adjustment plugs in correspondingly designated holes, LOW, MEDIUM, or HIGH.
    (2) Initial settings of the coarse and fine plugs, when charging two batteries BB-46 in series, are as follows:
    Coarse adjustment plugs in hole 4;
    Fine adjustment .p^ugs in hole marked LOW.
    Turn the control switch to the ON position. The charging rate will be the sum of the two ammeter readings. If the charging rate is not
    16
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 6-7
    high enough, turn the control switch to the OFF position and move both fine adjustment plugs to the MEDIUM position. Turn the rectifier on again. If the charging rate is still too low, the same procedure should be fol owed, and the fine adjustment plugs moved to the HIGH position. If still unable to obtain a charging rate as high as desired, again turn off the control switch and move the coarse adjustment plugs to the next higher numbered hole and the fine adjustment plugs to the LOW position and proceed as before. If the charging rate is too high, follow the reverse procedure, by moving the coarse adjustment plugs to the next lower numbered hole, and the fine adjustment plugs to the HIGH position. The fine adjustment plugs are then moved to the MEDIUM or LOW position as required.
    CciuHon.—Always turn the control switch to the OFF position before making anv adjustment to the rectifier, otherwise the tubes may be severely damaged.
    (3) Charging rate.—Reference should be made to TM 11-430 for the proper charging rate for the various types of storage batteries encountered in the field. Other information relating to the care and use of storage batteries may be found in the same reference.
    7. Cabinet BE-70-B.—The cabinet BE-70-B, wire chief’s testing cabinet, may be mounted in anv convenient location, either adjacent to the switchboard, or in the terminal room near the distributing frame. When the testing cabinet is located near the switchboard, connection may be made to the line to be tested by reaching across the face of the switchboard with the test cord from cabinet BE-70-B. When the testing cabinet is located near the main distributing frame, connections to the line to be tested may be made with a test shoe. The T, R, and S test cord terminals in cabinet BE-70-B may also be connected to the corresponding terminals of an outgoing line circuit, in order to provide means of testing lines from the switchboard, even though the testing cabinet may be located at some distance from the switchboard. Connection between the outgoing line circuit jack and the line jack of the circuit to be tested is made at the switchboard by means of a patching cord. The outgoing line circuit must be of the type that has no series or bridged line equipment, such as is shown in figure 10. Details of installation and method of operation of cabinet BE-7Q-B are covered in TM 11-345.
    17
    TM 11-340
    8	SIGNAL CORPS
    Section III
    DETAILED FUNCTIONING OF PARTS
    Paragraph Switchboard BD-89-A ........................         >..........   8
    Magneto line circuit...........................................    9
    Common-battery line circuit .............................         10
    Outgoing line circuit ___________________________________________ 11
    Through line circuit ____________________________________________ 12
    Trunk circuit, two-way for connection to dial (automatic) telephone
    central office, and associated dial cord circuit_______________ 13
    Trunk circuit, two-way to manual common-battery telephone central
    office ________________________________________________________ 14
    Universal cord circuit...................................         15
    Ringing circuit .............................................     16
    Operator’s telephone circuit and grouping key circuit____________ 17
    Conference jack circuit .................................         18
    Switchboard test circuit..............................            19
    Night alarm circuit........................,.................     20
    Fuse alarm circuit.....................:............................. 21
    Battery and ground circuit, 24-volt........................       22
    Power and heating circuit, 110-120 volts, alternating current______ 23
    Cable connector circuit.........................              ....	24
    Working limits, general explanation......................   ...	.. 25
    Cabinet BE-79 .......................................             26
    Power equipment..................................         .....	27
    Storage battery ........................................          28
    Power panel............................................-........  29
    Cabinet BE-75..............................................       30
    Panel BD-98 _____________________________________________________ 31
    Telering 20-cycle power ringer, Model H . . ..	. ........  32
    No. 84F interrupter .....................................         33
    Power supply ........................................             34
    Rectifier RA-36-A, B, or C_______________________________________ 35
    Line test equipment—cabinet BE 70 B ........................      36
    8. Switchboard BD-89-A.—The switchboard cabinet, framework, mounting plates, and miscellaneous mechanical details were de1-signed for the mounting and assembly of standard telephone apparatus to form a telephone switchboard suitable for military use. Induction coil C-105, monitor coil C-278, jack JK-37, head and chest set HS-19, binding post TM-197, generator GN-41, and the terminal panel are of Signal Corps design and are used in other equipment. The remaining apparatus consists of standard commercial parts. See list of replaceable parts in paragraph 44.
    18
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2	8
    a. Equipment layout.—The front equipment layout is shown in figure 1 and described in paragraph 2a (2). The rear equipment layout is shown in figure 6. The lower section of the switchboard is occupied by the cords, a rack upon which are mounted all cord circuit relays, capacitors, operator’s telephone circuit apparatus, trunk circuit equipment, and switchboard fuses. All equipment associated with each individual circuit unit is mounted on individual mounting plates for ease in replacing complete units. The upper section of the switchboard is occupied by the jack and signal
    Figure 6.—Switchboard BD-89-A and junction box JB-19, rear view, cord circuit mounting plate removed.
    19
    TM 11-340
    8	SIGNAL CORPS
    equipment. The line binding post panel is mounted on the left-hand side of the switchboard, as viewed from the rear of the switchboard. The binding post panel may be unfastened from the supporting framework to provide access to the wiring side of the panel and to other apparatus. The binding post panel contains 150 binding posts in three vertical rows of 50 binding posts each. These binding posts are arranged to screw down on the spade-terminal strips attached to the cable which connects to cabinet BE-79. The binding post screws should be 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 cabinet BE-79.
    b. Tip, ring, and sleeve.—In subsequent discussions, frequent reference is made to the terms “tip,” “ring,” and “sleeve.” This method of designating the three conductors (two line wires and one control wire) is derived from the plug used on a manual switchboard. One of the cord conductors is connected to the tip of the plug, a second conductor is connected to the ring of the plug, and the third conductor (control wire) is connected to the sleeve of the plug. This method of distinguishing between the various cord conductors has been applied to the line circuit. The tip of the plug makes contact with the short spring of the jack. This jack spring is designated as the tip spring, and the side of the line connected to the tip spring is designated as the tip side of the line, or tip conductor (fig. 7). The ring of the plug makes contact with a longer jack spring. This longer jack spring is designated the ring spring,
    Sleeve
    TL-957A
    Figure 7.—Three-conductor plug and jack.
    3/eeve Spr/r?g Rin9	Dead Co//ar
    Jack------
    P/naSpr/n
    Tip^T/pSpr/ng
    and the side of the line connected to the ring spring is known as the ring side of the line, or ring conductor. The sleeve of the plug makes contact with the sleeve of the jack. The control wire connected to the sleeve of the jack is designated as the sleeve wire, and is used only to assist in controlling the supervisory relays in the cord circuit.
    20
    Piug^
    TM 11—340
    TELEPHONE CENTRAL OFFICE SET TC-2 8-9
    c. Circuits.—The various circuits are designed for use in a 24-volt non-multiple switchboard. The relay adjustment data are given in paragraph 42. Detailed description of the various circuits appears in the following paragraphs 9 to 24 inclusive.
    9. Magneto line circuit (fig. 8).—This circuit is for use with equipment that uses 16- to 20-cycle ringing current for signaling. Since direct current is not applied to the line through this circuit, it cannot be used with telephones or circuits which require an external source of transmitter current (common-battery telephones), or for telephones or circuits which require direct current for supervisory purposes. The application of ringing current from the line to the circuit causes the drop to fall. When a plug is inserted into the jack, the drop is mechanically restored and the winding of the drop is disconnected from the line at the cut-off contacts in the jack. Contacts are provided on the drop to supply ground to a night alarm circuit which provides, when desired, an audible signal when a drop falls. (See par. 20.) The magneto line circuit may be connected to the following types of equipment or circuits:
    a.	Signal Corps type local-battery (magneto) telephones such as telephone EE-3, EE-4, EE-5, EE-8, and EE-8-A.
    b.	Commercial type magneto telephones.
    a 20	1350A I	BINDING POSTS ON
    7	f—/a/w-N— panel on rear of
    TO**.	SW. BD.
    ~ I ° BR X
    COMBINED JACK & SIGNAL SHALL OPERATE ON 90V. 16 2/3 CYCLE RINGING CURRENT WHEN IN SERIES WITH 1000n.N.I.RES. THE SIGNAL BEING SHUNTED BY AN 80J1 N.I.RES.'	TL-4155
    Figure 8.—Magneto line circuit.
    c.	Switchboards, as follows: Magneto line circuits in switchboards BD-14, BD-71, BD-72, BD-80, BD-89-A, BD-91, BD-96, and commercial magneto switchboards; line circuits equipped with ring-down relays and arranged for two-way ringing in commercial
    21
    TM 11-340
    9-10
    SIGNAL CORPS
    common-battery switchboards, switchboards BD-74 and BD-78. For two-way service connect this circuit to a circuit in the distant switchboard which is equipped with a drop or ring-down relay. For incoming service only at switchboard BD-89-A, connect this circuit to a jack circuit (such as shown in fig. 10) at the distant switchboard. This latter connection may also apply to interposition trunks when three or more switchboards BD-89-A, B, or C, are installed as one exchange.
    10. Common-battery line circuit (fig. 9).—This circuit is for use with telephones and circuits that require an external source of transmitter current and which signal switchboard BD-89-A by closing a d-c path.
    a.	Connecting circuits.—The common-battery line circuit may be connected to the following types of equipment or circuits:
    (1)	Telephones EE-8 and EE-8-A (with screw switch turned to CB).
    (2)	Commercial common-battery telephones.
    (3)	Trunk circuits that are arranged at the distant switchboard for incoming a-c ringing signals and outgoing d-c signals.
    b.	Working limits.— (1) Maximum external circuit loop resistance, 300 ohms.
    (2)	Minimum insulation resistance, 10,000 ohms.
    The maximum external circuit loop resistance includes the resistance of the conductors from the switchboard to the telephone, plus the internal resistance of that portion of the telephone circuit through which the line current flows.
    22
    SL J.
    r—“ SL-WH 5. •	, .\
    ________I__5k___|_S BL v". 'r BL.	CI---------------------N	J	\|n W MTG. BrOIRF^ 	HpWJJRJ---------------- X l-^^Z-. /
    ANj£T FTT F ' ,	. 2Uf SL .1	|	DIAL “ P a L
    r^.| Li? V 0R__________i-°R___________□.	~r~TT^'fia red | n	JACK	-3	sl |
    r, lIZTgZI | zjf y -rzif ,	|0	52n‘-,	fn-J	r-|l|h—= ,IOOOn S AClXXl	T \ -	«	I J]
    flYZXSZia^ 4 Is______	12 OR-WH .?? OR-WH <-,	L—$	,--- -fl I , > RED-GR 900A	_?T^ \ ■ 11	S	I
    Izril 3 r 8	pj1 ; J J.&
    Sy |	F 24Vu |2i! "jjAqiis _________gl nr- ’	a o^C2'
    —^rn. , " I ,	-mmm—m. «—■■■■«■■	— _5^221	REAR OF SWBD.
    _	ALL WIRING TO BE’20
    -----------------*EO-BW_I 1 FED-gR____________________ RED-BR 3----------------------'l TO ANSWER------------------------------------------------------------------------- -©^--	rN.ACKT
    LAMP	r„ I || or„_„	I LEAD PER POS.	> FIG 28
    (P=>-----------RED-GR X RED-WH _______________________________ FOR ALL TYPES OF TRKSj--------------------------------------------.
    S-—I K	'”	r IT-/ I -	REFERENCES
    ■A 24V	1	EQWpj (TRKS. OIAL)^ ,' AMp	» INDICATES INSIDE TERMINAL
    X	■ I.-(SR)SLOW TO RELEASE
    FIR 19	TOTRier I I	I I	-TERMINAL DESIGNATION ON
    rlV’-	LAMP!---- I	I -S-24V.	reLAY MOUNTING
    s'c^tV	O^uS^'^un^^110" on
    ANS. JACK & LAMP EQUIP--4—-------------------— RELAY EQUIP----------------- O _______________ CONCENTRIC	A.C, RELAY
    ■I—_jL	SL	ABC	— — — — Fl |*iz!SIX|lSRR|NG PILE upf el
    ®	3	“	C	XX XX	iu“!? f numbering j ::
    fcu	REpj—-------- •	--------W^F BL|	9	• -7-7INS.de WINDING1^’'
    S3	BR COILj	«	soon_RED-WH_________II X	1® 2£	22	» 0 L G> ’	’
    tl A5^R---------------3 I ---------1-•—5t^!-------------TH12	- - -	17 L\*-^>ouT5,de WINDING
    “«	’	?	? OR I 1 OR	350n<-,	24V.	J----------- LI
    Zu	ci—-}1	------1--©---- n»	*---llll—,	LI	TA5M!N^L NUMBERING ON AUTO-
    I-l’	[j—1	Zuf T T2-lJ I 2----------------------------'---------fl ’	TERMINAL STRIP	MATIC ELECTRIC CO TYPE RELAYS
    O^XTI r4>BFoRA?H-| ©|	]	-------------------------1
    05	L—J	L__J3 L I	Till—4|2	If-' RED-BR 3^ TO
    F	BR-WH^^3 r	L-\32 .3|	--i2>	33^ Ijyj---J-N.A .CKT.
    1_____ bl-wh	—TH33 sl	FIG-2a
    R, R SL-WH	_____J	|	I OR-WH JjXy|4 SL.WH ((Loon I3I-1L X	notes:
    RED-BR | X RED BRp-fl^jU	°	I-WIRES NOT OTHERWISE SPEc'd SHALL
    REAR OF SWBD.	------®----------Ll 24	. BE 22’
    I LEAD PER POS FOR	2-ALL BAT. LEADS SHALL BE BLK-RED*20.
    OR-WH	S?	ALL TYPES OF TRKS	3".A.LL GRD LEADS SHALL BE BLK'20.
    ---------------------------------------------—~ -	----1	/	4- F BRING FROM CABLE FORM AT SEPARATE ANSWER	|----------------211Y-----------/	»/ /	STITCH.
    LAMR	..	TO ~	-----X. - .	5- CONTACTS X OPERATES FIRST.
    ___-RED-GR I » RED-GR--------------------------------------EQUIP" (TRKS. MAN.) ~ 4aMR	6-WORKING LIMITS OF FIG. 12 ' pia |4 __K_____________i ®----------------------------------------—1	' ------MAX. EXT CKT. LOOP 750 ft " 750 n. 1_______________TO ; rf fl	MIN- 'NS. RES. 15,000ft iqooOft
    5“’	FIS. 13	®P, J,. ,h~
    5CKTS. SCKTS.	TL-4159
    ■ANS. JACK 1 LAMP EQUIP'
    Figure 12.—Trunk circuit, two-way, for connection to dial system exchange, and associated dial cord circuit. Figure 13.—Trunk circuit, incoming ring-down, outgoing automatic, for connection to qommon-battery manual exchange,
    28
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 13-14
    when the trunk to the dial central office is of such length that auxiliary long-trunk equipment is required at the dial central office. These auxiliary long-trunk circuits used at the dial central office are usually not designed to furnish reverse battery for supervisory purposes; consequently when such equipment is used on a dial trunk from switchboard BD-89-A, no supervision will be indicated by the cord lamp associated with the cord connected to the trunk jack. If it is desired that the supervisory lamp remain unlighted at all times rather than lighted, it is only necessary to reverse the trunk line connections at the terminals in cabinet BE-79. Should supervision of the above type be encountered and it is definitely known that there is no auxiliary long-trunk equipment in the dial central office, it is an indication of a trouble condition existing in some portion of the circuit.
    14. Trunk circuit, two-way to manual common-battery telephone central office.—Figure 13 shows the trunk circuit used to provide two-way service between switchboard BD-89-A and a common-battery manual exchange. This circuit should be connected to a common-battery manual line circuit equipped with a line relay of approximately 2,000 ohms resistance at the distant switchboard. (This precludes connection to the common-battery line circuit of telephone central office set TC-1 if correct supervision is desired.) It may be connected in place of, or bridged across, any manual telephone which is connected to a common-battery manual switchboard.
    a.	Working limits.—The working limits of the manual commonbattery central office will usually be controlling.
    (1)	Maximum external loop resistance, 750 ohms.
    (2)	Minimum insulation resistance, 10.000 ohms.
    b.	Functions.—(1) Provides for a ring-down signal and lights a lamp to signal the operator on incoming calls from the central office.
    (2)	Extinguishes the signal lamp and closes a metallic bridge, over the trunk to cut off (trip) the ringing current and provide for supervision when the operator answers.
    (3)	Extends supervision from the loop to the cord circuit when the central office disconnects.
    (4)	Opens the loop to the central office and prepares the circuit for an incoming call when the operator disconnects.
    (5)	Closes the loop to signal the central office when the operator seizes the trunk.
    29
    TM 11-340
    14	SIGNAL CORRS
    (6)	Releases and extends supervision to the central office when the operator disconnects.
    c.	Detailed description of incoming calls.—(1) On incoming calls, relay C operates from ringing current applied at the central office, locks itself to ground at a spring of relay A, lights the ANS lamp, and connects ground to the NA lead to provide for an audible signal. When the operator plugs into the ANS jack, relay A operates through the ground made at the jack. This opens the locking circuit to relay C, which releases, extinguishing the ANS lamp, and removing ground from the NA lead. Relay A also connects the winding of relay B in series with the line side of the repeating coil across the trunk to give answer supervision to the central office. Relay B operates at this time and connects a 500-ohm resistor R1 in a loop to the cord circuit, causing the A relay in the cord circuit to operate and extinguish the cord-supervisory lamp in switchboard BD-89-A. Relay B operates in series with the battery-supply apparatus in the central office cord circuit, and releases in series with the line relay at the central office. For this purpose the resistances of the cord-circuit battery-supply apparatus and the line relay at the central office should be approximately 200 ohms and 2,000 ohms respectively. The value of 200 ohms resistance of the cord-circuit battery-supply apparatus is an average value. In actual practice the resistance of the cord-circuit battery-supply apparatus may vary considerably from the average value of 200 ohms, and is dependent upon the type of switchboard, and the service for which it is designed. The resistance of line relays may also vary somewhat from the average value of 2,000 ohms, stated above. Probably the most extreme case that will be encountered in actual practice will be on trunk circuits of such length that an auxiliary long-trunk circuit is required at the commercial central office end of the circuit. In such cases the resistance in series with the batterysupply apparatus, connected to the central office end of the trunk circuit may be as low as 125 ohms, instead of the 2,000-ohm line relay and 200-ohm (average) cord circuit. The trunk circuit of switchboard BD-89-A will still function properly under such conditions except that disconnect supervision will not be received and it will be necessary to depend upon supervision indicated by the cord connected to the local station.
    (2)	When the central office disconnects, the line relay at the central office is connected to the line, and the resistance in the
    30
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 14-15
    circuit to relay B is increased. Relay B releases and the cord supervisory lamp lights through the release of relay A in the cord circuit.
    (3)	When the plug is removed from the ANS jack, relay A releases and disconnects the winding of relay B from the trunk, thus opening the holding bridge and extending disconnect supervision to the central office.
    d.	Detailed description of outgoing calls.—(1) On outgoing calls when a plug is inserted in the trunk ANS jack, relay A operates and closes a metallic bridge across the trunk through the line side of the repeating coil and the winding of relay B in series. The line relay at the central office is in series with relay B and operates to signal the central office operator. Relay B does not operate at this time, and the loop to the cord circuit remains open, allowing the cord-circuit supervisory lamp to light. When the central office answers, the resistance in the circuit to relay B is decreased, causing relay B to operate, connecting a 500-ohm resistor in a loop to the cord circuit which extinguishes the cord-supervisory lamp through the operation of the cord circuit A relay.
    (2) When the central office disconnects, the action is the same as described in subparagraph 14c (2), preceding.
    (3) When the switchboard BD-89-A operator disconnects by removing the plug from the ANS jack, relay A releases and disconnects the winding of relay B from the trunk, thus opening the holding bridge and extending disconnect supervision to the central office.
    e. An exception to the above operation will be encountered on trunk circuits of such length that an auxiliary long-trunk circuit is required at the central office. In such cases there is no change in resistance in the central office equipment when the central office operator disconnects. Therefore, the operator at switchboard BD-89-A must depend upon supervision from the answering-cord supervisory lamp on outgoing trunk calls and upon supervision from the calling-cord supervisory lamp on incoming calls. This condition will, in all probability, be encountered rather infrequently in actual practice.
    15. Universal cord circuit (fig. 14).—This cord circuit is of the universal type; that is, it provides for connection between two common-battery lines, between two magneto lines, between a common-battery line and a magneto line, and between a magneto line and a common-battery line. Supervision on common-battery lines is
    31
    TM 11-340
    15	SIGNAL CORPS
    indicated by cord supervisory lamps located on the keyshelf between the keys and plugs. Recall and disconnect signals on magneto lines are indicated by lamp signals located in the face of the switchboard below the magneto line signals (drops).
    a. Working limits.— (1) Common-battery line circuits.— (a) Maximum external circuit loop resistance; for supervision, 1,200 ohms; for transmitter battery supply, 700 ohms.
    (b) Minimum insulation resistance 5,000 ohms.
    (2) Magneto line circuits, using telephone EE-8 or EE-8-A.— (a) Maximum external loop resistance, 15,000 ohms; minimum line insulation resistance, 30,000 ohms, or
    (b) Maximum external loop, 7,000 ohms; minimum line insulation resistance, 1,000 ohms.
    (3) Dial and manual trunk circuits.—When connected to these circuits, no cord-circuit working limits apply, since the working limits of the trunk circuits in BD-89-A apply.
    b.	Functions.— (1) Supplies transmitter battery to commonbattery telephones.
    (2)	Provides means for supervising battery-operated trunk circuits and common-battery line circuits.
    (3)	Provides a non-locking lamp ring-off signal on magneto lines.
    (4)	Provides means for connecting the operator’s telephone set to the cord circuit.
    (5)	Provides means for ringing on either the tip or ring of the calling cord.
    c.	Connection to magneto lines.— (1) Incoming calls.—When the plug of the answering cord is inserted in the jack of a magneto line circuit the ES relay does not operate, since the sleeve circuit of the line jack is open. Under this condition the three windings of the A relay are connected series-aiding and remain bridged across the tip and ring of the answering cord for ring-off supervision. The operator answers the call with the TALK key in the operated position.
    (2) Outgoing calls.—When the plug of the calling cord is inserted into a jack of a magneto line circuit the FS relay does not operate since the sleeve circuit of the line jack is open. Under this condition the three windings of the C relay are connected seriesaiding and remain bridged across the tip and ring of the calling cord for ring-off supervision. Upon the operation of the ringing key, ringing current is applied to the line. Except while ringing
    32
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 15
    CORO CIRCUIT
    A' --------------— । • \-------------------------------1------------------------------7------;-------------------------V
    5WBD. EQUIP	-- relAy EQUIP------------------------4-------------SWBD. EQUIP-------*•
    * TO OPERATOR'S
    answer^	I	A	RS	FC	r	I TELCKVIC16
    (REAR)	-	A	bS	C	/—--1--
    PLUG T OR I 4, OR________________________ 7,__________________________BL 2	| BL R
    °-	®	II---------------<:■	•	—i
    T-Js	Zxuf
    x|	I	RED-WH_______________________________________RED-GR
    ?	lOOOn.	•
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    £	K I I L n	। 24V ,N I-	P— ------------
    answer	,	o uH1 •“ft"	i.i, /- Fl t!
    (SUPERVISORY)^----REP/.SL -----RED^L___L_ F,< 4250h	- 7u< TzSOn	TALK RING,
    !•	I	ArTLa ------------rtz^Tiz	I ,	SL CALL
    RECALL,—a___RED-BL I X RED-BL__________HJ	RED-BL	II FT°---	o	__,	| (FRONT)
    LAMPOy	- ..2	------Fisl_Ji________________________GR____ o	1SG
    ■ 1 Is ^JV-l 32	^'1^	। 2,122	1	°TZX,
    2^	.	100^ = 7^2	31OS Psi-^-L	rTl SL~WH
    _E	>	2 v*IOOn.	KL£jn T	I	4—°T
    -	(___ |gr-wh L__-,.M|	♦—Oil
    I	,3>420n wh	»2 "Uoon.	I	_________J
    I	J 1j24	°°ft 4	_____________________________35) (SUPERVISORY)
    I	wh 42°R<-;--i	lamp
    O	24 LJ ?
    OR-WH | 2or.wh^	'	''" t l BL~WH	v 2 Jy
    2MF	, TO RINGING
    CKT FIG.IS •.--
    I LEAD PER
    ---------------------------------  3 0R4CKTS.-1	_ . REFERENCES-----------------------.	D ♦ TALK
    » INDICATES INSIDE TERMINAL	TO RELAYS (.___IL- _(-)_,	D ♦ RING
    -®- TERM. DESIG. ON RELAY MTG. PLATE	BS AND FS _'	T (CDS1'±’
    -O-TERM. DESIG. ON FUSE MTG. PLATE	OTHER EQUIP L__AT O 0	___
    TRIPLE WOUND	l_S—l-L AMP i 24V.
    CONCENTRIC	CONCENTRIC	RECALl/^—1	I PER 3 OR T
    1 SPRING P|LE J ’'I ’??’??	LAMPS /	4 CKTS.	. TERMINAL STRIP
    IlfJup numbering! ,[f 4; »	_____________
    -----r— INSIDE —I-4 3	2 T"I	IT ‘ J WDG’' L • ° •	A 2. I A
    ~V~' /	NOTES:	12 II 10	9	9
    -----TV	I. WIRES NOT OTHERWISE SPECIFIED SHALL BE “»22.	— — — — LOUTSIDE X.INSIDE	\OUTSIDE I	2. ALL BATT. LEADS SHALL BE 8LK-RED s20.	A A J4 J3
    WDG.43	WDG.»2	WDG.	3. ALL GRD. LEADS SHALL BE BLK “ 20.	20 19 IB 17	17
    TERMINAL NUMBERING ON AUTOMATIC ELECTRIC ?	4." L" DENOTES LOCKING.	— — — —
    TYPE RELAYS	5. "NL” DENOTES NON-LOCKING.	U_
    ---------------------------------- LJ	TL-416 0
    Figure 14.—Cord circuit.
    33
    TM 11-340
    15	SIGNAL CORPS
    on the line, the TALK key is operated so that the operator may know when the call is answered at the distant end of the line, since no supervision is obtained when the call is answered.
    (3) Completion of conversation.—When a conversation is completed, ringing current should be applied to the line by either telephone user, in tne case of line-to-line connection, or by the distant switchboard operator in the case of a switchboard-to-switchboard connection. Ringing current over the line associated with the answering cord will operate the A relay. Ringing current over the line associated with the calling cord will operate the C relay. Operation of either the A or C relay will cause the RECALL lamp to light and remain lighted as long as ringing current is being received over the line.
    d.	Connection to outgoing and through line circuits.—The operation is the same as for outgoing magneto line calls and for completion of such calls.
    e.	Connection to conference circuit.—When the plug of a cord is inserted in a conference circuit jack, the BS or FS relay does not operate because the jack circuit is open at the sleeve. Under this condition the three windings of the A or C relay are connected series-aiding and remain bridged across the tip and ring of the cord. In the normal use of the conference circuit the relays associated with1 the half of the cord circuit connected to the conference jack do not function.
    f.	Connection to common-battery lines.— (1) Incoming calls.— When the plug of the answering cord is inserted in the jack of a common-battery line in response to a call, the BS relay operates, due to the ground on the line jack sleeve, and the supervisory lamp associated with the answering cord lights momentarily. The operation of the BS relay connects ground and battery respectively, , to the tip and ring of the cord through the No. 1 and No. 2 windings of the A relay, thus providing for transmitter and supervisory battery through the common-battery line circuit. In the event that the distant telephone is a telephone EE-8-A, separate transmitter battery is also provided at the telephone. The A relay operates since the circuit through its windings is completed at the distant telephone. The operation of the A relay short-circuits the supervisory lamp, thus extinguishing the lamp. The operator answers the call with the TALK key in the operated position.
    (2) Outgoing calls.—When the plug of the calling cord is inserted in a common-battery line circuit jack, the FS relay operates and
    34
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 15-16
    the associated supervisory lamp lights in series with the FS relay. The operation of the FS relay connects ground and battery respectively to the tip and ring of the calling cord through the No. 1 and No. 2 windings of the C relay. Operation of the ringing key applies ringing current to the line. When the called telephone answers, the C relay operates and short-circuits the supervisory lamp, thus extinguishing the lamp.
    (3) Completion of conversation.—When a conversation is completed, the parties hang up, and the circuit is broken at the switchhook or lever switch in the telephone, thus causing the A or C relay to release, which in turn causes the associated supervisory lamp to light. Removal of the plug from the jack releases the BS or FS relay and extinguishes the supervisory lamp, thereby restoring the circuit to normal.
    g. Connection to dial and manual trunk circuits.—The operation of the cord circuit is the same as the operation of the circuit when it is connected to a common-battery line circuit except that the circuit through the windings of the A or C relay is completed in the trunk circuit switchboard equipment instead of through the distant telephone. Therefore no cord circuit working limits apply.
    Figure 15.—Ringing circuit.
    16. Ringing circuit (fig. 15).—The ringing circuit provides two-party selective ringing. Two-party selective ringing is used only on common-battery lines, and then only when it is desired to utilize party line service. The telephone instruments used for this type of service will be commercial type common-battery instruments with the bell circuit connected between ground and either the tip or ring of the line as desired. The master ringing key is the first
    35
    TO TEST CKT , FIG.2I
    ' + GRD) O—T-xy	NOTES-
    J	1 L kpv	I. ALL LEADS SHALL BE » 20
    p	'io YEL-GR r~2~T r-.	AND "C" WIRING.
    §	m I mo kfv f7	2. "G" WIRING TO BE SEPARATE
    a*	4—,	I	GN-41 GEN. CABLE. SEWED TO OUTSIDE OF
    ~। RED__________rrmB= regular cable.
    8-“	rl-o—*, , o	rhlLLt 3. "F" BRING FROM CABLE FORM
    z RED-GR \ Is?—} 7,	j	AT separate stitch.
    k	“ RED-GR t	4. "L" DENOTES LOCKING.
    KO f'RING GRD. YEL 1 RED 6------------------------------------------
    F-*	n
    Uz .	r	Q
    Ogg t YEL-GR_______________________RES. D 1 MR
    °	LAMP □	TL-4I6I
    TM 11-340
    16
    SIGNAL CORPS
    (__________ OPR’S TEL. CKT. ______________ i _____________ OPR’S TEL. CKT. ____________________
    KEY 1 JACK EQUIP.	MTG. PLATE EQUIP.
    _____BL_________1__________BL_________________ Fl ________________
    I 4_ 3_ 2 l_	I
    ________SL ________5 S|_	e 7 6 5
    7	Z71 2 llf	12 IL 10 2.	9
    RED	« RED___T IND COIL	12 12. 14 12
    C-105	20 19 18 17	17
    YEL	* YEL_______________-I	J_____________ L
    _	q	jC.Pn <- UTERMINAL STRIP
    5	r-as---------i-------------	-~F bl
    R GR. MON । Q----------------SL ------®L gn
    4 I00H Fl BL C 3
    •T5 BR	------—-----------•--------J	2xxf
    R5 RED-BR >	LLq-J RED-ORI__________£____________ c _ ’24V( > RED-bJ^_X_^
    2	0.3jwf loon _
    T6 OR	YEL-GR _____‘ YEL-GR_____________
    RED-BL
    R6 RED-OR	RED-GR	RED-GR
    I------------- *	1 C2
    ________________________RED-SL I____g reD-SL T
    F>,	BL I	® RED-BL
    T  ---O---—1-----------------------•	-----
    BL	BLK ?______>
    C «---O------------ X	TO RET. NOTES-
    	_______ ’	19---------’ COIL-A- TERM. DESIG. ON MTG. PLATES R ’JK-3P	”'S____“I—•------------------J	» INDICATES INSIDE TERMINAL
    2	I- ALL WIRES SHALL BE #20
    BR	al	2- ALL GRD. LEADS SHALL BE BLK #20
    T ’	0	^Z24V.	3- ALL BAT. LEADS SHALL BE BLK-RED #20
    n RED-BL y---—I VARISTOR A-	4-ml,. DENOTES LOCKING
    C* °	W\	•	'5-"F“ BRING FROM CABLE FORM AT SEP-
    Rw----o-RED^BR---AR ATE STITCH.
    JK’37	TL-4162
    Figure 16.—Operator’s telephone circuit.
    \ z v ______________________
    kl ‘9IJ	OS7 OlJ
    UMD 1MD HO1D3NNOD
    GdODOl 310VD OX
    36
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 16-17 ♦
    key on the left-hand side of the keyshelf and is engraved MR. When the MR key is in the normal position, ringing current is applied to the ring side of the line with the tip side grounded. When the MR key is operated (handle inclined towards the operator) ringing current is applied to the tip side of the line with the ring side grounded. The terminals for connecting ringing power are located to the right of the cordshelf in the rear of the switchboard. A key designated EMG KEY on the schematic drawing (marked RINGING KEY-HAND on the switchboard), is used for switching on either power ringing or the hand generator. This key is located in the lower left-hand corner of the face of switchboard BD-89-A. The hand generator is a generator GN-41. A resistor lamp located above the cordshelf in the rear of the switchboard is connected in series with the power ringing circuit so that ringing on a short-circuited or grounded line will not interfere with ringing on another switchboard position using the same source of ringing power.
    17. Operator’s telephone circuit and grouping key circuit (figs. 16 and 17).—An antisidetone telephone circuit which includes induction coil C-105, and is equivalent to the circuit in telephone EE-8-A, is provided in switchboard BD-89-A. A varistor is bridged across the receiver terminals to reduce acoustic shock to the operator from excessive voltages across the receiver terminals. The varistor consists of an arrangement of copper oxide disks, the resistance of
    INDUCTION COIL C-105	2xif
    r—iM
    SEC. °
    RETARD	2
    COIL ________S> 2
    " PRIM, p	T0
    r it—	C	- CORD
    L/,'" T ---------V 3	CIRCUIT
    HS-19	J
    rl—-n~~> । - h-' TERT' I
    TRANS. JL =“’	A 4
    (o)	Q ____,
    K______—~r—:X—I-----------------1|----2
    REC 1--U=)l-----J	II J TL-4163
    Figure 17.—Operator talking, functional diagram.
    which decreases as the applied voltage increases. The operation of the monitoring key (engraved MON) and a cord circuit key connects the 1-2 winding of monitor coil C-278 in series with two
    37
    TM 11-340
    17
    SIGNAL CORPS
    2-microfarad capacitors Cl and C2 across the cord circuit, which enables the operator to listen to the conversation without introducing any material transmission loss (fig. 18). A grouping key (figs. 16 and 19) is provided so that the cords of one switchboard BD-89-A may be used by the operator of an adjacent switchboard
    MONITOR COIL
    C-27S 2xif
    HS-19	pL-58	------0 9-----II---
    I	------- 4 L J I	11
    f*"|	r—|« o	J L	TO
    TRANS. JL °	—)	D f	"CORD
    ©	--o----4	4	2xjif	CIRCUIT
    It
    REC.	U	TL-4164
    Figure 18.—Operator monitoring, functional diagram.
    BD-89-A when the first switchboard is unattended. The grouping key is mounted on the keyshelf and is engraved GR. Head and chest sets HS-17-A, HS-19, and commercial types of head and
    ।	-----------------------1
    I	GROUPING KEY
    I OPERATOR'S f------------------- T
    !	—-----------------fl IT0 00R0
    ufsWBO --------7=U	‘ CIRCUITS 0F
    ,st	----------------------1st. SWBD.
    1	1	l R'
    I
    I-----------------------------------------1
    R 6 T 6 *R5* TF]
    |
    I JUNCTION BOX J><><
    JB-I9	at N> I
    I	R6 T6TR5TT5
    I----------------1_____________I
    I	GROUPING KEY
    I OPERATOR'S	4------° ---------------I—L1 TO CORD
    1 rTE=rm-?NE ---- - CIRCUITS OF
    ' 2„dCSWBD. -----^3-----c----------------L_ 2nd. SWBD.
    4_______
    '----------------------------------------1 TL-AI65
    Figure 19.—Grouping circuit, functional diagram.
    38
    TEXAS STATE COLLEGE FOR WO ME*
    LIBRARY
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 17-18
    chest sets that are equipped with plug PL-58 may be connected to the operator’s telephone circuit by plugging into either of the two jacks JK-37 mounted in the front of the keyshelf.
    18. Conference jack circuit (fig. 20).—a. This circuit consists of five jacks connected in parallel to enable the operator to connect a number of lines together for a conference. Cord circuits or patching cords may be used for connecting the various lines to the conference circuit. For limitations on use of patching cords, see paragraph b, following.
    BR
    BR-WH
    BR-WH
    BR
    BR-WH
    BR
    BR-WH
    TLt4I66
    Figure 20.—Conference jack circuit.
    BR
    b. The use of patching cords is desirable, whenever possible, in order to reduce the number of cord circuits required on a conference connection. However, on account of complications arising on common-battery connections due to battery-supply conditions, it will be necessary to use a cord circuit for each common-battery line connected to the conference. In the case of trunked connections
    39
    TM 11-340
    18-19	SIGNAL CORPS
    and magneto lines, patching cords may be used. It must be remembered, however, that at least one cord circuit must be used in each conference for purposes of supervising the entire conference. Patching cords are not issued as a part of TC-2. See paragraph c following.
    c. 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 improvised out of two switchboard cords whose corresponding terminals are securely fastened together, and the two conductors insulated from each other. Patching cords may also be used to tie circuits through the switchboard in a semi-permanent manner, thereby avoiding the use of a cord circuit. In case this use is made of patching cords, it must be remembered that there is no supervision on the circuits so connected.
    19. Switchboard test circuit (fig. 21).—This circuit is to be used in making routine tests of, and for locating trouble on the cord circuits, line circuits, trunk circuits, and the night alarm circuit. The tests are made by connecting the circuit under test to jacks in the switchboard test circuit either directly or by means of patching cords. The tests are made from the front of the switchboard. A visual or audible signal is provided for indicating the performance of the equipment under test. Before making the tests described below, the person making the tests must be familiar with paragraph 5, on operation of the switchboard.
    a.	Functions.— (1) To check the operation of the night alarm circuit.
    (2)	To test the lamps of common-battery line circuits.
    (3)	To apply an operation test to the drops of the magneto line circuits.
    (4)	To apply an operation test to the dial trunk circuit and the dial cord circuit.
    (5)	To apply an operation test to the manual trunk circuit.
    (6)	To test the cord circuits.
    b.	Detailed description of circuit operation.—(1) General.—If the circuit under test fails to operate as described, consult the detailed description of the particular circuit. Before readjusting any relays, the continuity of the circuit under consideration should be checked and tests made for other possible sources of trouble.
    40
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 19
    (2) Testing the night alarm circuit.—Test the night alarm circuit when tests on line and trunk circuits are made.
    TEST CORD,ONE REQUIRED, 6-0"LONG
    TEST
    CLIPS
    PATCHING CORD,ONE REQUIRED, 2'-o"LONG
    PLUG
    KEY ENDED CORD, ONE REQUIRED, 4-0"LONG
    KEY
    PATCHING CORD,ONE REQUIRED. 4’- 0' LONG
    TEST PLUG
    5
    RED-GR	aRI	) ZN
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    F U --r°“-S	I- WIRES NOT OTHERWISE SPECIFIED TO
    I--1 * z	BE*22.
    T £	2- ALL GROUND LEADS TO BE BLK * 20.
    Q £t I
    £ “
    C	*E¥ CALL A	!	c	|	SIAS E8IA jACK CREAR) |l00n<- c
    .j-irteEp-'"' 0^ E pO =J" t KpOr rari TM&i fl	LJ	D—»-J	J>	L 1________ IL 900AA.C.  J—I	500ft < ZL	4- ANSWER t  H
    I s,oon	fpy »	p——y4’	w - L
    71 ,   4=f i	, T—ioooi?Of14v-	feain	Kwontn J>25°a
    J4 L2)	____Zfc	|_ _J I______11 answer
    ^2=2 24 V TO RINGING	__C ‘	~~R)
    ■=	CIRCUIT	4-	T0 NIGHT	J L~’' •
    r NA ALARM CIRCUIT	24 * yi
    ____	_____~~n-~ &■----1---------------3 j--1	a
    c	r-An	I I	I	I	----1 Bins eejA answer answer r ”' fb Bs
    „ P_____, f(rCALP, A	I	B	rx	500ft?	JACK CREAR) ,00A <- r~i n_ I >	[-1 ? f-o-1	dial	b	a L-AAA/-<	r-0-1
    Op r0 ^1 pUtH Mt TfO TCU „„&Jb ’	i —J------------------------L=24kl|
    tff...	'	■	““5
    CORD CIRCUIT	SWITCHBOARD TEST CIRCUIT	DIAL TRUNK CIRCUIT	CORD CIRCUIT
    FIG. 22 ,
    •	400	_____~~TT;	®---T-----------------,	--
    RINGING	I--•---WV----1	------ C „__________________ A	1 r I	A e
    nn CALL n	I * n	24V	350ft	a	500n A ANSWER ANSWER |)O0ft H) BS
    pppyr yiiz_____________________________r r ~ y Hj iUFy
    !—J_	CALL i	i-	2"f	L“O"£}-]	- ANSWER	ff
    ,n ,________Ln>	*	JW {P (P------------------- , P
    ^PJ'OOOA fj	______________-24V	? r answer ,000n bj3250n
    ‘"*~^L24V. ro RINGING	_T~* □__________ ■ J f	,24V. ^2
    -	CIRCU'T	-	°	■ -■ ro NIGHT	rlzrP	-«•
    y-—L	^NA ALARM CIRCUIT	24M “
    CORD CIRCUIT	SWITCHBOARD TEST CIRCUIT	MANUAL TRUNK CIRCUIT	CORD CIRCUIT
    FIG. 23	TL_4168
    Figure 22.—Test of dial trunk circuit, functional diagram.
    Figure 23.—Test of manual trunk circuit, functional diagram.
    TM 11-340
    19
    SIGNAL CORPS
    (g) Replace the heat coils or close the circuit at the terminal strip when the test is completed.
    (6)	Testing the common-battery manual trunk circuits (fig. 23). — (a) Disconnect the circuit by removing the heat coils, or open the circuit at the terminal strip.
    (b)	Insert into the B jack the plug of the test cord equipped with test clips. Attach the test clips to the manual trunk circuit binding posts marked T and R on the rear of the switchboard. Insert into the A jack a calling (front) plug of any cord circuit. The supervisory lamp of this cord should light from ground on the sleeve of the A jack.
    (c)	Apply ringing current to the cord in the A jack. The C relay of the trunk circuit should operate, locking itself up through ground on a contact of the trunk circuit A relay, lighting the manual trunk lamp and operating the audible signal of the night alarm circuit if the night alarm key is in the normal position.
    (d)	Insert an answering (rear) plug of any cord circuit into the manual trunk jack. This action operates the trunk circuit A relay from ground on one of the answer jack contacts. Operation of the A relay causes the release of the trunk circuit C relay, which in turn extinguishes the trunk answer lamp and stops the night alarm audible signal. Operation of the trunk circuit A relay also connects the winding of the trunk circuit B relay in series with the line windings of the repeating coil across the line, causing the B relay to operate from battery and ground supplied by the cord circuit connected to the A jack of the test circuit. Operation of the trunk circuit B relay connects a 500-ohm resistor across the line in a loop to the cord circuit, which results in the supervisory lamp of this cord being shunted out.
    (e)	Replace heat coils or close the circuit at the terminal strip when the test is completed.
    (7) Testing the universal cord circuits.—The cord circuit lamps on the keyshelf are referred to as supervisory lamps. The cord circuit lamps on the switchboard face above the plugs are referred to as recall lamps. (Used only for disconnect or recall on magneto lines.)
    (a)	Operate and release test of supervisory relays A and C (fig. 24).—Insert the answering (rear) plug of the cord under test into the C jack and connect the test cord equipped with the key to the F jack. The supervisory lamp of the cord under test should light
    44
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 19
    until the key is operated. Operation of the key completes a circuit through the 1 and 2 windings of the cord circuit A relay, which operates, shorting out the supervisory lamp and causing it to be extinguished. Operate the key momentarily to apply a “soak” current to the supervisory relay. Withdraw the plug of the key-ended cord from the F jack and insert into the A jack. Operate the key to apply an operate test current to the supervisory relay. Release the key to apply the release test current to the supervisory relay. If the lamp remains lighted after operation of the key, failure of the supervisory relay to operate on the operate test value is indicated. Failure of the supervisory lamp to light upon release of the key indicates failure of the supervisory relay to release on the release test current. Repeat this test with the calling (front) plug inserted into the C jack instead of the answering (rear) plug in order to test the C supervisory relay. Test all cord circuits in the same manner.
    ANSWER ____n BS
    F	Crear)_^jiooa --o——
    ANSWER	I
    700ft VvC	IQOOft	250ft
    A	I	24 V
    A °C	< 4000ft
    | l00A I____1------------------- TL-4169
    SWITCHBOARD TEST CIRCUIT	CORD CIRCUIT
    Figure 24.—Test of supervisory relays, functional diagram.
    (b)	Ringing current operate test of the three windings of supervisory relays A and C, and ringing-key test (fig. 25).—Insert either plug of a cord circuit into the B jack and the plug of a calling (front) cord of another cord circuit into the F jack. Apply ringing current to the cord in the F jack. The recall lamp of the cord connected to the B jack should light. The 1,800-ohm resistor connected to the sleeve of the B jack prevents either the FS or BS relay of the cord circuit from operating This is a test of the operation of the supervisory relay of the cord connected to the B jack and a test of the ringing key of the cord connected to the F jack. Repeat this test until all answering (rear) plugs and calling (front)
    45
    TM11-340
    19—20
    SIGNAL CORPS
    plugs have been tested in the B jack, and all.calling (front) plugs, have been tested in the F jack.
    RINGING
    KEY	300/1 700/1 400/1	EITHER ------R>
    I  CALL	_AAA A A A , A A  	tllntH 100/1 ( ’
    U	4000/1 rx H	’ lIOOJ1<" >	j-----
    1	@=-------—r-ifl	F© RECALL
    TO RINGING	T	IQOOn lq 4-k 250/1
    CIRCUIT	JU	— 24V
    24V -7-	R
    TL-4I7O
    CORD CIRCUIT	SWITCHBOARD TEST CIRCUIT	CORD CIRCUIT
    Figure 25.—Ringing test of supervisory relays, functional diagram.
    c.	Non-operate test of the sleeve relays BS and FS and direct-current operate test of the three windings of supervisory relays A and C (fig. 26).—Insert either plug of any cord circuit into the C jack, and insert into the B jack the answering (rear) plug of the cord under test. The recall lamp of the cord under test should light unless the lamp is defective. Failure of the recall lamp to light may indicate that the sleeve relay fails to meet its non-operate requirements or that the supervisory A relay does not meet the direct-current operate test with the three windings in series. Repeat this test with the calling (front) plug of the cord under test inserted into the B jack in order to test the FS and C relays. Test all cord circuits in the same manner.
    (d)	Operate test of sleeve relays BS and FS (fig. 27).—Insert either plug of any cord circuit into the B jack and insert into the A jack the answering (rear) plug of the cord under test. If the sleeve relay of the cord under test operates satisfactorily, the recall lamp of the cord connected to the B jack should light. Repeat this test with the calling (front) plug of the cord under test inserted into the A jack. Test all cord circuits in the same manner.
    (e)	Test of talking keys.—Insert the calling (front) plug of the cord under test in the E jack and operate the TALK key. The ringing current connected to the E jack should be heard in the operator’s headset. If the power ringing machine is not operating the hand generator must be used to supply ringing current.
    20. Night alarm circuit (fig. 28).—The use of series line circuits makes the use of a conventional night alarm circuit unsatisfactory. The combined leakage current of all the line lamps in series with their respective lines causes an appreciable amount of line lamp current to flow at all times even when all lamps are idle. This amount
    46
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 20
    47
    A
    n EITHER	300.fi. 700ft.	400ft	____n
    —O-------,	ANSWERp^:^
    -A	c	n /-x_i	X	 □	, _____Q 24V.
    c ; ~ ~	Pv	U''—?	<
    ____________"	(- >10031	[	T T	J.	|	T	L-rj	o-- 1 -=±=-RECALL I "J °	»	$	‘‘	>	S ANSWER	I ’
    x—T I	’—	—-y -		a	____________________£ CORDS 7-9
    ■o	'	•----------~
    O j	L_________________________j CORDS 10-13
    ®	T	'
    ______Z_________________________2 OPERATORS TEL.
    FA	F®	6 LINE VARISTORS
    BUZZER	~——------------------------------•------------
    v	c	? U T ? r	-- J* LINE LAMPS THRU
    *\	21-------1--- Z8 /N.A. CIRCUIT
    i	• >	DtAL TRUNK
    __________“__________________j°	MANUAL TRUNK _________^.SPABE	£
    A	B	I2SPARE	A
    ___________ • BUf-WB------------------------------*	g
    21____RCO-OR	O	S_____________TO LINE LAMPS
    22	' o	■ ■■ ■ "—- ■1 ■ b ksnno	| •	'
    — Fl n	RED-SL kj4 RED-SL
    , > 85n RED-CR 32 LJ	-----—----------------------- Hu
    ,,___ZT3Z	---Iff 31	RED-BL	2T-- RED-BL	*
    *	- > 4000a	23 7	-----------------•--------------- .. u
    8LK	----- e §
    Pts	-
    REO-BR ----- T	J______________&______REO-BR______ N.A. Q o
    ©\	REO-BR	”	REO-BR	T
    ,	»----------	/-----*---------------------—f
    C	BLUE - BR__c ____24______BL-BR	—o—>
    -TI0N ON MOUNTING
    13	I-WIRES NOT OTHERWISE SPEC D SHALL	PLATES
    — — — —	BE “20.
    Z— - — -	17	2-ALL BAT. LEADS SHALL BE BLK-RED *20-	TWO SECT coding PIL F-
    _____21	3-ZLL GRD. LEADS SHALL BE BLK *20-	--14 UP NUMBER-28 27 2 6 25	>5	4“ .DENOTE LOCKING.	L|NG
    ----- 	25	5-'NL DENOTES NON-LOCKING.	| —-----?9	6-F’BRING	FROM CABLE FORM AT SEPARATE	.	WIND"
    33	STITCH.	■	’ <-» /ING
    ™ ™	7-"C‘WIRING SHALL BE SEPARATE CABLE	\° •/.ARM. END
    - - - -	37	SEWED TO OUTSIDE OF REGULAR CABLE-	--SECT.-I)
    J____________ LJ	TERMINAL NUMBERING ON
    AUTOMATIC ELECTRIC CO. TYPE RELAYS
    TERMINAL STRIP TL-4172
    Figure 28.—Night alarm, fuse alarm, battery, and ground circuit.
    TM 11-340
    20-23
    SIGNAL CORPS
    the alarm
    the trunk when the
    winding of the transformer and the low-resistance winding of relay A in series. When the NA RLS key is restored, the circuit to the high-resistance winding of relay A is closed and the circuit is prepared for another signal.
    (3) Operation of the NA key disconnects the bell from the magneto line and trunk circuits, opens the circuits to both windings of relay A, and connects direct battery to the line lamp common, shunting the low-resistance winding of the transformer. This prevents the operation of the night alarm bell when either line or trunk signals are received. Restoring the NA key again prepares the circuit for audible signals.
    d. Magneto line and trunk signals.—When a magneto line or a trunk signal is received, direct ground is connected to the bell to sound an audible signal. The magneto line circuits and circuits are arranged to that the ground is removed operator answers, thus opening the circuit to the bell.
    21. Fuse alarm circuit (fig. 28).—When a fuse blows,
    contact of the fuse connects battery to the alarm bar, causing the buzzer to operate and provide an audible alarm. The buzzer continues to operate until the blown fuse is removed.
    22. Battery and ground circuit, 24 volts.—The 24-volt battery and ground circuit is shown in figure 28. The keyshelf ground terminal is located on the underside of the keyshelf at the left-hand side. The framework ground terminal is located on the iron framework between the two varistor groups.
    -O-C-! flush twist - lock plug Q Q BASE IN REAR CENTER OF _/\_/ SWBD
    #14-2 COND.^
    /
    EDISON BASE I	XA
    RECEPTACLE FOR Q	Q Q
    HEATER UNIT |	/VX
    DUPLEX RECEPTACLE TL-4173
    Figure 29.—Power and heating circuit, wiring diagram.
    23.	Power and heating circuit, 110—120 volts, alternating current (fig. 29).— This circuit includes two heating units for drying the switchboard and one outlet for soldering iron or extension lamp.
    50
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 24-25
    24.	Cable connector circuit (fig. 30).—This circuit is utilized in extending leads from the battery and ground circuit, ringing circuit, and grouping key contacts, to junction box JB-19. In the event that a second switchboard BD-89-A is required, this circuit is used to extend the above mentioned leads from the terminal strip of the adjacent switchboard to junction box JB-19 mounted in this switchboard.
    25.	Working limits, general explanation.—The term “maximum external circuit loop” means that the sum of the resistances of all lines and equipment connected to the circuit in question should not exceed the values stated, in order to insure that the circuit functions properly. For example, the maximum external circuit loop of the common-battery line circuit (fig. 9) is 300 ohms. If the resistance of the line between the switchboard and the telephone does not exceed 200 ohms and the resistance of the connected telephone is 100 ohms, the sum is 300 ohms or just equal to the maximum resistance allowed. The resistance of the common-battery holding coil in an EE-8-A telephone is 100 ohms. In the above case, if the 300-ohm limit is greatly exceeded the line lamp may not burn sufficiently bright. This effect will be come increasingly noticeable as the storage battery approaches a state of discharge. Another example of the
    51
    HEAVY DUTY ALL RUBBER COVERED
    CABLES
    /-------------1---------------\
    2 COND.	2 COND.	4 COND.
    ”16 A.W.G.	“18 A.W.G	“18 A.W.G.
    --------------------------A—H----------------------------------n®
    ---------------------U-----------Kjs ----------------------------------------------------------
    -------------------------------------Hf -------------------------------------------------- -------------------------
    --------------------------------------HpS
    ।---------------—u----------------ns
    p cj
    j.-.--	.................. .........	... i TERMINAL STRIP	i “ .
    'l^tttttt00,
    T5|	'	CABLE
    CONNECTOR
    . ran +------------------------52 _£ jd	FOR CONNECTION
    \\	-/	T6	TO JUNCTION BOX JB-19
    ---1-- -----1------------------------RS °H
    TO N.A. BATT TO	---------- I O
    AND GRD. RINGING	H
    CKT FIG. £8	CKT.
    FIG.I5	TL-4174
    Figure 30.—Cable connector circuit, wiring diagram.
    TM 11-340
    25-26	SIGNAL CORPS
    use of working limits is as follows: Circuits in two different switchboards are to be connected together. One switchboard circuit has a working limit of 750 ohms, and the other switchboard circuit has a working limit of 1,000 ohms. In this case the 750-ohm limit is controlling. In each case it is necessary to use the sum of the line resistance plus the internal resistance in the distant connecting circuit in determining whether or not the value of maximum external circuit loop resistance will be exceeded. In case it is not possible to meet the working limits with one pair of conductors, it will be necessary to use two pairs in parallel, connected tip to tip and ring to ring at each end of the line.
    26.	Cabinet BE-79.—The arrangement of apparatus is shown in figure 2. An opening with a sliding cover is provided for incoming line wires in the lower part (each side) of the cabinet. An opening with a sliding cover is also provided in each side of the cover on the switchboard side of the cabinet, for the cables to the switchboard. This allows the covers to be put in place after the installation of the cabling. Space is provided below the protectors for 12 repeating coils C-161 (not furnished as part of the TC-2).
    a.	Cabling and cable connectors.—The cabling between cabinet BE-79 and switchboard BD-89-A consists of three rubber-jacketed ■cables, each containing 25 pairs of braid-covered, latex-insulated, No. 22 AWG stranded conductors. The cables, exclusive of the cable connectors, are 21 feet in length. The cable connector at the cabinet BE-79 end of the cable consists of a strip of insulating material on which is mounted a row of 50 binding posts to which the cable conductors are soldered. These soldered connections are inclosed in a copper-alloy protecting cover. Binding posts TM-197 are the same as those used on the terminal panel of switchboard BD-89-A. The cable connectors at the switchboard end of the cable consist of strips of insulating material between which is mounted a row of 50 spade terminals of Signal Corps design. The spade terminals are mounted in such a manner that some movement is allowed in order that the spade terminals will be self-alining when connections are made to binding posts TM-197 on switchboard BD-89-A terminal panel. The cable conductors are soldered to spade terminals. The soldered connections are inclosed in a copper-alloy protecting cover.
    b.	Protectors and associated terminal strips.—Two vertical strips of protectors are mounted in cabinet BE-79. Each strip is equipped
    52
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 26-31
    with 40 pairs of commercial high-potential protector blocks and heat coils. A terminal panel, equipped with 80 binding posts TM-197 for connecting the incoming lines, is mounted on the line side of the protectors. The central office side of the protectors is permanently wired to a terminal panel equipped with 80 binding posts from which the lines may be cross-connected to the repeating coils C-161 or to the cables to the switchboard.
    27.	Power equipment.—The power equipment included in the telephone central office set TC-2 is discussed in paragraphs 28 to 35, inclusive.
    28.	Storage battery.—a. The storage battery consists of two batteries BB-46 connected in series with cord CO-38. This provides a 24-volt, 75 ampere-hour, sealed type storage battery for furnishing direct current to switchboard BD-89-A. Cord CD-335 is provided for battery leads to panel BD-98. When in use, the battery is mounted on rack FM-31. Two cases CS-63 are furnished for transportation of batteries BB-46.
    b. Rack FM-31, hammer HM-5, and three ground rods GP-29 are transported in case CS-72.
    29.	Power Panel.—For power control and distribution one cabinet BE-75 and one panel BD-98 are provided. These, along with associated equipment, are discussed in paragraphs 30 to 35, inclusive.
    30.	Cabinet BE-75.—This cabinet provides for protection, control, and distribution of 110-120-volt a-c power. When in use, cabinet BE-75 is mounted on a rack FM-30 with rectifier RA-36-A, B, or C. Cord CD-393 is furnished for connecting cabinet BE-75 to a local source of alternating current, and cord CD-395 is furnished to connect cabinet BE-75 to switchboard BD-89-A. When a second switchboard BD-89-A is installed, a-c power is connected from the first switchboard to the second by means of cord CD-394. When any circuit-breaker switch is closed, a-c power supply is connected to the correspondingly numbered socket. For transportation, cabinet BE-75 is packed in the case CS-73 with the rack FM-30 and the rectifier RA-36-A, B, or C. (See par. 35 for discussion of rectifier RA-36-A, B, or C.)
    31.	Panel BD-98 (figs. 30 and 31).—This panel contains a voltmeter and an ammeter for controlling the rate of charge of the storage batteries and is equipped with a Telering 20-cycle power ringer (see par. 32) which supplies ringing current when 60-cycle
    53
    TM 11-340
    31
    SIGNAL CORPS
    110 V. 60 CYCLE
    ALTERNATING i---------------------------------1
    CURRENT ,	RTE TELERING MODEL H
    J CHOKE 1
    FJ 1 T O ----------9-------------t-f-L—I	"T
    g s	nJ	jy-choke	h
    _______I 6 jt	"“ZL C-^IOOA. -|-0.05uf.	g
    I	---1 O.laf. = = I ”
    .	D.C. POWER SERVICE CONNECTIONS	.	J O.luf. I onnn _	F?
    Ft—1----------------------------------------- < 2000 A _L f |
    --•L- i	< LAMP	I -J
    I	I A----------4-----(T)-----------—1---- H
    F	t'i	n	+'i	n	I	50 watt
    aL J L (Al L (8) 4		\ >	' POST >	____________ - z w
    *	24 V. ZZ -----------1	!---------------------------WESTERN I	' z ©
    o — BATT.	,	। ELECTRIC I	EQ-
     Q---A <250-0-1 o.85g S2-7-0-) g J-F----------------------------------------------------< ^KEY~ f 6 I n? 18 I £
    INTERRUPTER °<\	| Fl <	J-0	°—H'	° °	---- -
    CIRCUIT ))	|	—V I	I	I
    BREAKER ?v 1	<■-<-	©--1	1------------1
    10 AMPS.	I	LJ
    —Lj____________	1
    1__________________________j
    «	TL-4175
    Figure 31.—Panel BD-98, schematic diagram.
    54
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 31-33
    alternating-current power is available, and an interrupter for providing ringing current from the battery power supply. The Telering 20-cycle power ringer is operated by plugging its power supply cord into a power outlet in cabinet BE-75 and closing the circuit-breaker switch corresponding to the power outlet selected. The interrupter (see par. 33) is started by the operation of the INT circuit-breaker switch on panel BD-98 and the interrupter circuit is completed by operating the rotating button-type key on the interrupter. Closing the A and B or the C circuit-breaker switches connects the 24-volt bus bars to the A and B sockets or to the C binding posts, respectively, which provide spare power terminals. The closing of the MAIN circuit-breaker switch connects the battery socket to the bus bars. A schematic diagram is shown in figure 31. Case CS-71 is furnished for transportation of panel BD-98.
    32.	Telering 20-cycle power ringer, Model H (figs. 31 and 32).—The Telering 20-cycle power ringer is a vibrating-reed type of frequency converter. It is designed to supply 20-cycle ringing current from a 110-volt, 60-cycle, a-c power supply. The reed vibrates between a contact screw and an electromagnet. The contact screw adjustment is set at the factory, and it is 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, cause sparking, interfere with radio reception, and may prevent starting.
    33.	No. 84F interrupter (fig. 31).—a. The Western Electric Company 84F interrupter is a vibrating pole-changer type of ringer for converting direct current into alternating current for ringing. When the interrupter is properly adjusted, it is sparkless and noiseless in operation. When the machine is in constant use, daily inspection should be made to check for the following:
    (1)	Sparking at contacts.
    (2)	Noisy operation.
    (3)	Tendency of armature to stick to magneto (operating coils).
    (4)	Short circuits.
    55
    TM 11-340
    33
    SIGNAL CORPS
    Figure 32.—Telering ringer, cover removed, showing vibrator assembly.
    b. A weekly inspection of the condition of the contacts should also be made. If sparking occurs at the contacts in the operating magneto, they should be polished. If the ringing contacts spark, they should be polished. If polishing does not eliminate the sparking, the ringing springs should be readjusted. Do not attempt to adjust the springs without disconnecting the ringing battery at the fuses. If the armature can be made to lock by pushing it toward the magneto while the interrupter is in operation, the setscrew should be unscrewed slightly. If the adjustment of the ringing springs is affected by readjustment of the setscrew, a complete readjustment of the ringing springs should be made. The position of the weighting nut on the threaded screw at the end of the armature governs the frequency of vibration of the armature. The nut should be at approximately the center of the threaded portion of the screw. If the vibrating arm strikes the magnet, the operation of the
    56
    -Contact 'Adjusting j Screw 11 nh
    —Contact I Point I II I '! I
    ~A/ibra ting Peed
    i I1'
    TL-W7
    Electro I h| Magnet^
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 33-36
    interrupter will be noisy. To eliminate the noise from this source, all the ringing springs should be moved in such a manner that the vibrating arm will be farther away from the magnet. The interrupter should then be completely readjusted.
    34.	Power supply.—Telephone central office set TC-2 is equipped to operate from 110-120-volt, 60-cycle, a-c power. Power unit PE-75-A, B, or C is provided to serve as a source of local power, in case commercial 110-120-volt, 60-cycle, a-c power is not available. The power unit is furnished with a collapsible case for transportation. Refer to TM 11-900 or TM 11-901 as required for operating instructions for power unit PE-75-A, B, or C.
    35.	Rectifier RA-36-A, B, or C.—This rectifier is provided for charging batteries BB-46. It is designed to mount on rack FM-30 and to operate from 100-125-volt, 60-cycle, a-c power. The rectifier is of the full-wave type and is adjustable for charging a 24-volt storage battery at a rate of from 2 to 12 amperes. The rectifier is transported in case CS-73. For detailed information on the adjustment of the rectifier for varying the charging rate, consult the instructions outlined in paragraph 6c. Figure 33 shows the circuit diagram of the rectifier.
    36.	Line test equipment—Cabinet BE—70—B.—A cabinet BE—70—B (wire chief’s testing cabinet) and its packing case, case CS-57, are furnished (see TM 11-345 for detailed functioning of parts). The cabinet is designed to make the following tests or operations on magneto and 24-volt common-battery telephone lines:
    a.	Talking to telephone user.
    b.	Talking on telephone trunks.
    c.	Talking on two call wires.
    d.	Ringing.
    e.	Continuity tests.
    f.	Tests for short circuits.
    g.	Tests for grounds.
    h.	Tests for crosses with lines carrying current.
    i.	Tests for crosses with other lines.
    j.	Location of crosses or grounds by means of a Wheatstone bridge (not furnished as part of telephone central office set TC-2)/
    k.	Ballistic capacity tests.
    Z. Measuring test-battery voltage.
    57
    TM 11-340
    36
    SIGNAL CORPS
    Fuses-I5amp
    (	^Bu/b cat /89049
    Bu/b cat/89049
    End
    End

    5/
    See.st.
    A-C
    Ammeter TypeO~7
    St.
    L End
    P/ay board
    Ammeter Type 0-7
    Pt ay .
    board
    I ^Capacitor 2 mfd Catbsx/as
    I
    Start
    Taped over tap tor use on 40 v . c/rcu/t
    End
    Start
    S/'ny/e connec/ot ■
    (Taped x over)
    Pr/.end jpz’/Tn
    —: qjL switch —	>/ Cat235685
    Figure 33.—Rectifier RA-36-A, B, or C, circuit diagram.
    58
    +2?-C
    §
    *»)
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 37-38
    Section IV
    SERVICING AND REPAIR
    Paragraph
    Maintenance ______________________________________________________ 37
    Alarm-type fuses .......................................           38
    Storage batteries ------------------------------------------------ 39
    Switchboard plugs, cleaning___________________________________ 40
    Manufacturer’s drawings ___________________________________ .. . —	41
    Relay adjustment data--------------------------------------------- 42
    Packing for army transportation____________ ________ .... . .... _ 43
    37. Maintenance.—a. General.—The greatest single factor in trouble-free operation is careful handling of the equipment while packing and unpacking, transporting, and installing. After the installation has been completed, all circuits, fuses, and protector blocks should be tested at least once each month, or more often where climatic conditions warrant.
    b. Circuit breakers.—When a circuit breaker opens its circuit due to a flow of excessive current, the circuit breaker should not be re-closed until the cause of the excessive current has been determined and corrected. After the circuit breaker has tripped, the handle must be returned to the OFF position for resetting before the circuit breaker can be re-closed. The trip position can be readily recognized as a position midway between ON and OFF.
    c. Working limits.—The loop resistance and insulation resistance of the lines connected to the switchboard should be maintained within the limits specified on the respective circuits. However, the loop resistance of common-battery lines may exceed the values specified on the drawings, provided the brightness of the switchboard lamp is satisfactory.
    38.	Alarm type fuses.—Inspection of an alarm type fuse will show that the fuse wire holds two springs under tension. In case a fuse is blown, the tension on the two springs is released and they assume different positions with respect to the body of the fuse. The front spring (with the glass bead) serves as a visual indication of the condition of the fuse, and the back spring serves to complete the fuse alarm circuit, thus giving an audible signal to indicate a blown fuse. Alarm type fuses must be properly installed in the fuse mounting in order that advantage may be taken of the alarm feature. The fuse must be so installed that the bent end of the
    59
    TM 11-340
    38-41
    SIGNAL CORPS
    alarm contact spring (back spring) will be directly over the alarm contact stud, or alarm bus bar, on the fuse mounting. If the fuse has been improperly installed, the alarm circuit will not be completed, and consequently no alarm will be received. However, the fuse will be blown under overload conditions, thereby protecting the equipment.
    39.	Storage Batteries.—The electrolyte in the storage batteries should be maintained at the proper level. The voltage of the battery should be as follows:
    Not less than 22 volts.
    Not more than 30 volts if batteries are charged during use. Between 25.2 and 26.4 volts if the batteries are trickle-charged or floated.
    Caution.—Violent gassing and a rise in temperature of the electrolyte are two indications of too high a charging current. Keep open flames, lighted cigarettes, and other burning articles away from the batteries at all times. Poor connections cause sparking and are therefore a very dangerous fire hazard. Do not change connections without turning off the MAIN circuit breaker on panel BD-98. The instructions for the care and use of the battery, outlined in TM 11-430, should be carefully followed.
    40.	Switchboard plugs, cleaning.—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. The use of light oil and cake rouge is the 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 the polishing operation. Pour a few drops of light oil on the cake of rouge, thereby softening the rouge to such an extent that when the polishing rag is rubbed across the surface of the cake, a small amount of the rouge is transferred to the rag. Care must be taken when using either the 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.
    41.	Manufacturer’s drawings.—a. Relay terminal numbering.—The manufacturer’s drawings furnished with switchboard BD-89-A, and the figures used in this manual show sample diagrams of relay winding terminals and relay spring pile-up numbering as viewed
    60
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 41-42
    from the rear or wiring side of the relay. The diagrams do not show the complete numbering scheme, but do show the general system. For example, in figure 14, cord circuit, relays BS and FS each have a set of make contacts with springs numbered 11/. and 15. The sample diagram showing the spring pile-up numbering does not show either of these springs. However, it will be found springs Ilf. and 15 on the relay are in the same vertical row of the spring pileup as springs 11, 12, and 13, and are immediately above them in numerical order. For this general type of relay of Automatic Electric Company manufacture, the following rule may prove helpful: The first digit of the spring number denotes the vertical row; for example 1 indicates the left-hand vertical row, 2 the middle row, and 3 the right-hand row, as viewed from the rear or wiring side. The second digit of the spring number indicates the vertical position of the spring as counted from the bottom of the spring pile-up. For example, spring No. 25 will appear in the center vertical row and will be the fifth spring from the bottom. Each small solid semi-circle, shown on both the schematic drawings and the terminal diagrams, denotes the terminal of the inner end of a relay winding. This terminal is usually connected to the ground or low-potential side of the connected circuit, while the battery or high-potential side of the circuit is connected to the unmarked or outside ending of the relay winding.
    b. Color of wires.—The manufacturer’s drawings and the figures in this manual show, in most cases, the color of the wire connected to the various terminals. In a few isolated cases it may be found that the color of the wire used in wiring the equipment does not correspond with the color shown on the drawings. If such conditions are encountered, it will be necessary to use care in checking the wiring, to see that the same color of wire is connected to the appropriate terminals, even though the color used differs from that specified on the drawings. An example of this condition has been located in some cord circuit relay units, which are wired as follows (reference fig. 14): A RED instead of a WHITE wire is used to make the connection between the inner terminal of winding No. 3 of the A relay and spring No. 31 of the BS relay. A like substitution has also been made, in some cases, between corresponding terminals of the C and FS relays.
    42.	Relay adjustment data.—Table I gives the necessary information for making mechanical and electrical adjustments on the various
    61
    62
    TM 11-340
    42	SIGNAL CORPS
    TABLE I
    CIRCUIT REQUIREMENTS
    Mechanical requirements	Circuit preparation	Direct current flow requirements
    Appara- ------------------------------------- -----------------------------------------------	Test-------------------------------------------“----
    tug	Contact data	Test clip data	After	Re-
    desig- Arm.	Spring Separa- Block	prep. Test Test soak Test ^adjust
    nation travel screw	tion	Conn. bat.	Conn. grd. See	wdg. f°r
    1	projection	2	note .	3	4 Amp. Amp. Amp.
    Trunk circuit, dial, figure 12
    (Repeating Coil) ( Repeating Coil) B/G.... (52 ) O..............................0397...	,0365....
    A..........020".. .0015"..... 21-22.. .010"_........ ....	(Terminal 5 J (Terminal 8 J ..............do..... (ohm) NO................... .0293...	.0327...
    B..................0015"____ 11-12.. .015"................................. Jack Spring............ G...... ......... O....... ...........0153...	.0135....
    12-13.. .010"...................................    do—...........—- do............... NO.............. .0105... .0118....
    ................. 14-15.. .010"................................................................................................................. ................. 31-33.	.016".....             —.....................................................-...-...............-................ ................ 32-33.. .010".... ................................................. ... -..    -.....................-............  -
    (Spring	1 do... L........ O------------------ .0170....1 .0159....
    C........ .020". .0015"...... All......OlO".... (B)O...................... ( Relay(D) (____________| do. . I......... NO.............. .0131.... .0144...
    /Spring #2 1 (Spring #1 )	I B/G............ O.—............... .0056.... .0052....
    D..........025"........... 3-4.... .015"________________ (Relay (D) J (Relay (D) J.................... do............ NO..................0044.....0047. ..
    Trunk circuit, manual, figure 13 A..................0015"____ 11-12.. .015"................................ Jack Spring............ G................. O................. .0169.....0153....
    ................. 13-14. .010"...________________________________________do.......-	do............. NO.................0121.... .0126.... ................ 31-32	.015".________    1	..................................................... ................. 32-33.. .010"._______________________________................................... ..............................................
    L .	j,, . ) f- .	«„)	B/G............ O.__.............. .0169.... ,0157...
    B..........015". .020"...... 21-22.. ,010"......................  Ct"	’... Ct"b'.................. d°.............. NO-..................0129.....0137....
    (Relay (A) j Relay (A) j	do............. RLS.................0100............
    TM 11-340
    TELEPHONE CENTRAL
    OFFICE SET TC-2
    42
    63
    .	Mechanical requirements	Circuit preparation	Direct current flow requirements
    a. p par a.- —	.	----------------------------- Test--------------------------------------1 "---
    tus	Contact data	Test clip data	After •	Re-
    desig- Arm. Residual gprjng Separa- Block	nrpn Test Test soak Test adjust
    screw	picp.
    nation travel . x. No. tion	Conn. bat. Conn. grd. See	wdg. Ior---------------------------
    1	projection	2	note g	4 Amp. Amp. Amp.
    C........034".. .0015"- 11-12. .025"......... /Spring #31/. /Spring #32 /._ 5.. do--- f300 / O.............. .0314.0286...
    .............. 13-14.. .010".......... /Relay (C) / /Relay (A) /	5...... do. (ohm/ NO............. -0232.... .0256.... ............- 31-32- .015"-.......... /Spring	#12 L-. 5’ 6- G........ /350 / O......... .0169.... .0154.... ..— ........- 33-34.. .010"-.........  /Relay..........(C) /		......... /ohm/ ..........................-....
    Cord circuit, figure 14
    A &	(BS> or
    C.........' . .006"... 21-22.. .010".... (FS)O—_....................      7.	M8____ 1 & 2.... O.__. .069. -0137.0130....
    (BS) or
    ................ 22-23 ...006".... (FS)O......................       7.. M8.... 1 & 2.... RLS..____.... .0076.... .008......
    M 8._... 1.2&3 0............ .0072........
    BS& ......... ,0015"...... 11-12.. .015"...............     [Spring	#13 ]	.... G___________ O.._........... .033...... .0297....
    FS.................... 12-13.. .010".............          [Relay	(BS) !■ .... G..........    NO............ .0242.0263....
    ............. 14-15.. .010"......................... [or (FS) J......: ..'.        — ............... 31-32.. .015"..      '.	.................... ............... ...........1 32-33.. .010".........................................................................................
    Night alarm circuit, figure 28 A...... .020". .0015".. 21-22.. .010"........ /Spring #32 1. /Transformer/.... 9...... B/G—- /85 / O........ -0273...0244—
    ..................-.................-........ /Relay (B) / /Terminal #5/	9...... B/G— /ohm / NO........ .0188.... .0211... B..........  .0015"... 11-12- .010"..........       /Spring	#21/	 G............... O._........... .0170...0153—
    ..........-.-.. 23-24- .010"...................   /Relay..........(A) /....... G.__.....   NO............... .0121— .0135.... ..................... .31-32	.015 " .............    —...........	.......	............................................. _______-.............. 32-33.. .010"......             1...................................................................
    Note: 1 See parts list for Automatic Electric Company code numbers.
    2	Letter to left of dash denotes relay to be blocked in the operated or nonoperated position as specified. 3 “B/G” denotes that test set is to supply battery and ground. “M” denotes metallic connection, battery and ground to be supplied by the circuit. “G” denotes that test set is to supply ground. 4 “O” denotes operation. “NO” denotes nonoperation. “RLS” denotes release.
    5	Insulate springs #11 and #12 of relay (A).
    6	Operation of spring #11 and #12 of relay (C) only.
    7	Windings in series aiding. Block (BS)O when adjusting (A), and block (FS)O when adjusting (C).
    8	Connect to terminals on cord-shelf, windings in series aiding.
    9	Operate NA key to disconnect battery from 4,000-ohm winding.
    TM 11-340
    42
    SIGNAL CORPS
    Figure 34.—Cabinet BE-79, cables secured for transportation.
    64
    tl-4176
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 42-43
    relays. The necessary equipment for making these adjustments is not included as a part of TC-2; therefore, these adjustments should not be attempted in the field, but should be performed by signal repair companies or higher repair echelons.
    Figure 35.—Cabinet BE-79, ready for transportation.
    43. Packing for army transportation.—Remove the spade-terminal strips from the switchboard BD-89-A and fasten them to the associated binding post terminals in cabinet BE-79. Coil up the cables and strap them in place as shown in figure 34. Fasten the cabinet
    65

    TM 11-340
    43
    SIGNAL CORPS
    covers in place as shown in figure 35. Pack the head and chest sets HS-19 in the compartment in the front cover of switchboard BD-89-A. Loosen the designation strip mounting screws (at the extreme ends of the strip) and lower the supports to fasten the drops in place. Tighten the screws sufficiently to hold the drops securely. Place the cord weights in the cord-weight support and fasten the support in place as shown in figure 36. Fasten all switch-
    Figure 36.—Switchboard BD-89-A, front panel removed, showing cord weights secured for transportation.
    board covers in place as shown in figure 37. Remove rack FM-30 containing rectifier RA-36-A, B, or C, and cabinet BE-75, and pack them, assembled, in case CS-73. Pack each battery BB-46 in
    66
    Ti.-4f78
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 43
    one case CS-63. Pack rack FM-31, hammer HM-5, and three ground rods GP-29, in case CS-72. Pack cabinet BE-70-B (wire chief’s test set) in case CS-57. Pack the operator’s chair M-205 in case CS-70. Pack panel BE-98 in case CS-71. The packing case for power unit PE-75-A, B, or C, also provides room for cord CD-409.
    Figure 37.—Switchboard BD-89-A, ready for transportation
    67
    7Z-4/7P
    TM 11-340
    44
    SIGNAL CORPS
    Section V
    REPLACEABLE PARTS
    Paragraph List of replaceable parts .......................   -.. 44
    Addresses of manufacturers .........................-.- 45
    44. List of replaceable parts.—The following list of major component parts is further expanded in succeeding subparagraphs dealing with the larger items of equipment.
    68
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 44
    69
    a. Telephone central office set TC-2.
    c, 1	.	Ref-
    N	Name	Descnption	Function	par.
    °'__________________________________________________________________________________________No.
    4C9989A.. Switchboard BD-89-A........................... Switching central..... .............   445
    4E1179.—.. Cabinet BE-79................................ Main distributing	frame............... 44c
    3H4098.... Panel BD-98.................................. Power panel...................  ,.....  44
    4E1175---- Cabinet BE-75—............................... A-c power distribution—............... 44e
    4E2917--- Junction box JB—19............................ Cable connections. .................   44/
    4B1279--- Head and chest set HS—19.....................— Operator's set.....................    44g
    3H4676( )_ Rectifier RA-36-A, B.................   _.... For charging BB-46...............      445
    ......... Maintenance equipment ME-6-.».	In chest CH-59_ For maintenance._______________________ 44 f 6R38044.. Tool equipment TE-44—A..... In	chest CH-58____ Provides tools...._   44/
    3B46----- Battery BB-46................................. Switchboard d-c power..................
    3F2405( )- Cabinet BE-70-B.............................. Wire chief’s testing cabinet................
    3F2570.... Case CS-57................................... For	cabinet BE-70-B—...................
    3B863----- Case CS—63................................... For	battery BB—46...........................
    4C2905.1-- Case CS-70................................... For chair M-205.............................
    3H771.... Case CS-71.................................... For	panel BD-98.............................
    3B872----- Case CS-72................................... For	rack FM-31, hammer HM-5 and 3 ground rods
    GP-29
    3Z973—.... Case CS-73..........—........................ For rectifier RA-36-( ), cabinet BE-75 and rack FM-30
    4C2905.1_ Chair M—205................................... Operator’s chair—...........................
    3E1335.... Cord CD-335—.............   30	' long—....... Battery cord............................
    3E1393   Cord CD-393.................. 50	' long........ Cabinet BE-75 to a-c power. ................
    3E1394   Cord CD-394.................   8	' long ....... Switchboard BD-89-A to switchboard BD-89-A, a-c
    power
    3E1395____ Cord CD-395—............... 30	' long........ Cabinet BE-75 to switchboard BD-89-A....
    3E1409____ Cord CD-409................ 50	' long........ Power unit PE-75-( ) to cabinet BE-75......
    3E2038____ Cord CO-38................... 1' long..........—Battery BB-46 to battery BB-46............
    3E2258____ Cord CO-258..............   50	' long........ Ground cord.............................
    3E2259... Cord CO-259.................. 5	' long.—...... Cabinet BE-79 to cabinet BE-79, ground cord.
    3Z3329.... Ground rod GP-29......... Steel,	3 ' x 1\" dia...................-........................
    6Q49005___ Hammer HM-5......... Sledge, 12—lb....................................................
    3H4575( )._: Power unit PE-75-A, B or C................. Emergency a-c power.....................
    4E6530___ Rack FM-30.................................... For rectifier RA-36-( ) and cabinet BE-75—..
    4E6531____ Rack FM-31................................... For 2 batteries BB-46.......................
    6Z7510-1__ Paulin, duck.______________ 12.3/xl6/........ Equipment protection....................
    TM 11-340
    44
    SIGNAL CORPS
    70
    b. Switchboard BD-89-A.
    Ref. -Rpf	Stock	Mfr’s, oart Signal Corps
    fig. symbol	No.	Name ’	Description	j Function	Mfr.	No.	dwg. No-
    No.	I
    8.............     .....	Combined jack and 5 per strip...... Magneto line jack W. E. Co. 31C---- SC-D-6375
    signal	and signal
    9............ .......... Jack.............._..........—......Fine jack..........do.... 239B---------- Do.
    9... LINE..	......-..-	Lamp__ _______ Switchboard......... Line lamp..........do... B-2.._.... Do.
    9____________ __________ Varistor....... 1/10 of 300-A..._... Line lamp protection...do.....—. 300A-- Do.
    10......... 77........-.. Jack...............    .-........... Outgoing line circuit....do. 238B--------------- SC-D-6373
    11.. A B..7777........  —	Jack........  —..................... Through line circuit.do.............. 239B------ Do.
    12... Cl, C2. 7.7'.—-.... Capacitor..... 2/if................. Bypass..................... A. E. Co- D-68195-A. SC-F-3971 &
    SC—D-6377
    12.. C3 . __	........... Capacitor.........do........................ Blocking.....do............do......... Do.
    12..   C4._______________ Capacitor............do..................... Contact protection—...do.....do..... Do.
    12 ....	........... Coil.......... Repeating coil..........-....-............do... -- D-281686-A Do.
    ......... Type 2A
    12	.... Dial.......................................................... A. E. Co_ D-84760-A. Do.
    ......................—.	or W. E. Co,.... 5EB................................................................................ Do.
    12 ANSWER. ................ Jack...................................... Answering jack..._. W. E. Co— 241B.._. Do.
    12 ....... DIAL__. .7...... Jack....................  —....... Dial jack...........do.. 239B------------------- Do.
    12... ANSWER............... Lamp......... Switchboard_________________ Answering lamp......do....... Al...... Do.
    12„...................... Plug ........—- Switchboard................. Dial cord—.....do............ 310... Do.
    12™ A	Relay_____;....—..........-..-.............. Supervisory relay._ A. E. Co_ H-66470-1- Do.
    12 7.7 B 7.7777.7 777777777" Relay.................................... Sleeve relay. ....do. H-66470-2....... Do.
    12 .... C77.7 77Z ............	Relay.................................. Ring-down locking ...do.—. H-66470-9---- Do.
    relay
    12 D	Relay........—- ......-..................... Ring-down relay.....do.... H-60611-11.... Do.
    12 ”. Rl’, R2...7 77777.7. Resisto77777777_. 500 ohms........- Current limiting.--------.do..	H-60611-19.... Do.
    17 po	do	.600 ohms	.............. Contact protection......do.. H-66470-101.. Do.
    13 '77 ClZC2777777777:7777'Capacito7777777 2/if.7............- Bypass..-..... A. E. Co.— D-68195-A—... SC-F-3971 &
    bC—13—6377
    13	C3_..............     do......... 1...do—....................... Blocking...do......do................... Do.
    13	. Coil.......... Repeating coil......- ——-.........................do....... D-281686-A... Do.
    ---------------- '	Type 2A
    13 ANSWER	Jack...............  -....---...-..- Answering jack------------- W. E. Co. 241B... Do.
    13.. ANSWER 777 ” .....7.. Lamp.......... Switchboard.................. Answering lamp.....do....... Al........ Do.
    {3.. X.	7.7....... Relay....................................... Sleeve relay__ A. E. Co.... H-60611-24.... Do.
    13 B " .7.... 7777777"'do............................................. Supervisory relay...do. ..... H-60611-4. Do.
    13*.. q..—	...-.. ..... ............................ ..... Ring-down relay..-..........do....... H-66470-10.... Do.
    13... Ri ......................Resistor . .7...7ZZZ''' 560 ohms. ___ Current limiting-.....do....... H-60611-19....	Do.
    1477’’ C1,C2.............. Capacitor..... 2/if........................ Blocking.—.do....... D-68195-A.— SC-F-3972 &
    SC-D- 63 / 4
    14 TALK- .......... Key........	.__.’............................... Talking and ringing....do. D-321965... Do.
    14 ANSWER................ Lamp....................... -...-......... Supervisory... W. E. Co........ El...... Do.
    CALL	1
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 44
    71
    14.... RE- ................ Lamp................................... Ring-down super- W. E. Co..... Al........ Do.
    CALL	& visory
    14... ANSWER,.............. Plug----------------------------------- Answering or calling .do... 310............... Do.
    CALL	plug
    ... A C------------------ Relay.------------..........----------- Answering or calling A. E. Co. H-66470-3. Do. supervisory
    14.... BS, FS.................do......................................Back or front sleeve.. do.... H-66470-4_____ Do.
    . _	relay
    15.____________ 4B454.—.... Crank GC-9....................................................................... SC-D-4237
    J5-............ 4B841...... Generator GN-41----------------------------- Hand generator...  .1........... SC-D-6374
    15..- EMG............—..... Key..—................................. Emergency....... W. E. Co..... 498F._.... Do.
    15-... MR.........................do------------------------------------ Master ringing.. A. E. Co.._ D-321005.... Do.
    15.....—.....—.............. Resistor lamp.............................. Ballast lamp.... W. E. Co. 12Dor8D.. Do.
    16.- Cl, C2................ Capacitor........ 2 /JLf___________________ Blocking......... A. E. Co—.. D-68195-A .... SC-D-6375
    16 --. C3...............  —....do.......... 6 /if (three 2-/lf in parallel).... Bypass.-.  ..do,..do......... Do.
    16.... C4......................do----------- 0.5 /If...—............... Blocking..........do.. D-68211-A.......... Do.
    16............ 3C105—....... Coil C—105.  ............................. Induction coil.. ....................
    16—-.-....-..-.............. Coil C-278..... .......................... Monitor coil................. .....
    16..- A................—.... Coil........... Retardation coil------- Battery supply.....do..... H-66470-5.... Do.
    16_____________ 4C4277_____ Jack JK-37-...........................................................................
    16---- GR-MON... ......... Key----------------------------------------- Grouping and moni- _do. D-322147... Do.
    —	„	,	toiing
    16 —----------- 4C9971/136.... Varistor................................ Acoustic shock re- W. E. C-  3—A..... Do.
    duction
    20... A-E.................. Jack.................................... Conference cct......do.... 239B....... SC-D-6373
    21.................--------- Clip.. ........ Cord tip, for 2W6A cord___ Test cord..._...do_____ 59........... SC-D-6376
    21.......................... Cord..._....... Clip ended, 6 ' long..........do............do—... 2W6A_________ Do.
    21-----------------------------do........... Key ended, 4 ' long ..........do—...... A. E. Co.. H-66503........... Do.
    ......... assembly $2
    21.............................do........... Patching, 2 ' long-........do,....  ....... W. E. Co—. 2P4A.—.	Do.
    21..................—--------.....do........ Patching test, 4 ' long.—..do........   A.E.	Co___ H-66503.... Do.
    . „	assembly #1
    21-  A-D—...........—...... Jack........................................ Test jack.... W. E. Co.... 238B  	. Do.
    21..- E..._. —------------- Jack...___________________________________....do..........  do....	241B__ Do.
    21... F-G.......................do—....................................do-.......    ...do.... 238B___ Do.
    21--- KEY....--------------- Key------------ For A.E. Co. H-66503 as- Test cord.........do.... 522A....... SC-D-6376
    sembly #2
    21......................... Plug...,........ For test cords__________....do..........  .do.... 310........ Do.
    21.... TEST ............... Plug, test...... For A.E. Co. H-66503 as- _do..............do.	257A_	Do.
    PLUG	sembly #1
    21.... R1------------------ Resistor........ 100 ohms =*= 1%, 1-watt................ A. E. Co_ H-66470-102 Do.
    21--- R2----------------------.do...........  400	ohms	±	1%. 1-watt..................   do.... H-66470-104	Do.
    21--- R3.....................    do......... 4000	ohms	=*=	1%, 1-watt_____________      do.... H-66470-105..	Do.
    21.... R4....................  do........... 1800	ohms	=*=	1%, 1-watt.. .............. .do..... H-66470-103..	Do
    21... R5.---------------------..do.......... 300 ohms =*= 1%, 1-watt........    .-.......do___ H-66470-106.. \ Do.
    21---- R6.........do    .................... 700 ohms =*= 1%, 1-watt...........................do. H-66470-107.. Do.
    21.... R7................. Resistor.------- 1000 ohms 1%, 20-watts................. A. E. Co___ H-66470-108.. SC-D-6376
    21... R8...........;...........do------------- 200 ohms == 1%, 2-watts.—.......      —do...... H-6< 470-109 Do
    28....... BELL............. Bell................................... Night alarm........ do........ H-66470-8 .	SC-D-4264&
    ,	SC-D-6378
    28... FA--------------....- Buzzer.-------------------------------- Fuse alarm.......  do...... H-60611-14.... Do.
    28... A-------- ----------- Relay.................................. Impulse relay_________do.. H-66470-7.. Do.
    28... B..._....................do..........I----------------------- Lockout relay.__.J....do... H-66470-6. Do.
    TM 11-340
    44
    SIGNAL CORPS
    R.ef- Ref.	Stock	XT	r-	Mfr’s, part signal Corps
    jfig. symbol	No.	Name	Description	Function	Mfr.	No.	dwg. No.
    28.... NA.................. Key..................................... Night	alarm key. W. E. Co.. . 479DC...... Do.
    28.... NA	RLS............  Key..........................      -.-... Night	alarm release A. E. Co....... D-322154. Do.
    key
    28... RING ................. Transformer.......... Ring through transformer. Impulse transformer...do... D-282302-A.... Do.
    THRU
    28............. 3Z2135A_____ Fuse............ 1J amp., alarm type.... Circuit protection..... W. E. Co..... 35A__.. Do.
    30...................       Cable	connector.. Terminal strip and 3 rubber Extends d-c and a-c .........    —	SC-D-4258
    covered cables	switchboard power
    circuits to JB-19
    ..... ...................... Adapter.............. Composition....   Part	of heating unit Graybar.- KL_..... SC-D-4259 assembly
    ; ............................. Adapter, dial....     Part of dial mounting.. W. E. Cc— 52B    SC-D-4251
    ............... 3E1298/1-1. Angle.............. Spade terminal....... Cable	connector....................... SC-D-4287 ...........     Angle.................. Brass  ...................... Ca ble connector  .................... SC-D-4261
    terminal strip
    ..........  Base,	plug....... Flush.................. Part of heating unit	Graybar-— 8808... SC-D-4259 assembly
    ............... 3Z756.......... Binding post TM- 	  Line	and trunk ............................. SC-D-4255 197	binding posts
    ,.......................... Block, connecting_______________________ Dial mounting. .. W. E. Co.... 25B----- SC-D-4251
    .....................       Brace............ Keysheif brace........ To hold keyshelf ---do..... 11G—....... SC-D-4251
    open
    ....................... Bracket......._________ Cable bracket........ Holds	keyshelf form............................. Do. ....    do............................ ._______ Condenser mounting........-..............—-.............—... SC-D-4248 ............................do. Steel..............................  —	Part of heating unit
    assembly	...................... SC—D-4259
    ................. 4C2502L..... Cap, lamp...... Switchboard, green..... Cord	lamp cap---------- WE. Co. 2L......... SC-D-4251 . ............ 4C2502H...........do-..........—. Switchboard, red. ........do............... -.do...... 2H...... Do. ................. 4C2502AY—......do........... Switchboard, white.....do......do........................ 2AY...... Do. ........ 4C2504F.............._do............. ... Switchbeard, green. Recall	lamp cap--------.do......— 4F....... SC-D-4249 ................ 4C2504D.......do................. Switchboard, red—..do..—-------------------..do..... 4D......—-----Do ................. 4C2504A........do.............. Swdtchboard, white....do............do............... .... 4A. Do. .............................. do.............  do.................... Line and trunk lamp.....do...... 12AY...... Do.
    caps
    ............................ Clamp, cable... Phenolic, top section..    -.............................—	SC-D-4262 ............................do...... Phenolic, bottom section..—.........	...............—-...-...........—- Do. ........................ Connector.............. Armored cable connector..... Graybar — 2226-S............. SC-D-4259 Cord............................................ 5 green.................   Cord.circuit. W. E. Co.. .. S3B... SC-D-4243
    '....  ’__’.............—-....do........... 5 red.................... do.............—..do..... S3B........ Do.
    .....	.......................do............. 5 white	   Cord	circuit and dial .do.. S3B... Do. 	i...............cord circuit 	........ Form.............................. Switchboaid local cabling 	.................................... SC-D-4266
    form
    ................. 4C3709.... Fastener, cord.   Cord	terminal.....do---. 9.......... SC-D-4244 ................ 4C4247B... Hook, cord...... 14 per strip.....  —.....................-do----- 7B... Do. .............. Insulator..................... Phenolic............... Generator base-._------------............... SC-D-4247
    72
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 44
    73
    ................------------ Mounting, dial........................... Dial mounting... W. E. Co. 34E....._____ SC-D-4251 A. E. Co. D-78399-A____________________________________________________________________________________________ Do.
    .....—. Mounting, fuse....................... For alarm type fuses....__________________ W. E. Co. 12E......... SC-D-4254 .....................-. Mounting.............. Steel......—........... Support key ....................... SC-D-4251 mounting bars
    ............................ Nut, wing._________ 5/16", 18-thread..------..............................._...... SC-D-4257 .................-.. Plate, apparatus.__________ Phenolic, jack mounting-- Through lines, ................ SC-D-4249 conference circuit, test circuit, and outgoing lines
    —........................... Mounting, jack..............-..-......... ForJK-37................._.................. SC-D-4239
    .........-.................. Plate, apparatus____ Phenolic, jack and lamp Dial trunk, manual .................. SC-D-4249 mounting	trunks, and
    common battery lines
    .............-......  -...... Plate, apparatus___ Steel, magneto jack and signal Magneto lines.---------------- Do. mounting
    ---------------------------- Plate, designation_ Nickel silver, engraved .......................................... Do. RINGING KEY-HAND
    ..  --------------------.... Plate, floor..... Steel.............. Capacitor mounting.............................. SC-D-4248 ..................... Plate, inside........... Cover fastener..................................................... SC-D-4260 —.-............. Plate, outside...............—...do....................................................................... Do.
    .............. —	-.......... Plate, mounting.. Steel------------------ Cord circuit equip- ................... SC-D-4254 ment
    ............................ Plate, mounting......do.................. Dial trunk equip- ..................... Do. ment
    ........-.................L—	Plate, mounting............do........... Manual trunk equip- ........................ Do. ment
    —........................... Plate, mounting......do.................. Operator’s telephone ....................... Do.
    circuit equipment
    ............................ Plate, mounting ....do................... Night alarm, fuse .......................... Do. alarm, and protection equipment
    ....-....................... Plate.......... Phenolic................. End of cord shelt........................... SC-D-4251 ....-.............. Plate.................-.do........... Right end of key ................................. Do.
    shelf
    ............................. Plate...............do.................. Left end of keyshelf___________________ Do.
    ..........-................. Plate________________do...................... Line and trunk ......................... SC-D-4255 terminal strip
    ...■-.-................  ...	. Receptacle..... Composition, two pole, plug-... Part of heating unit Appleton_ 7685. SC-D-4259 > assembly
    .............. —..............  do............ Porcelain, rectangular—.do...................do.... 7660____________ Do.
    ............................ Resistor........ 250-ohm, 60-watt________ Heating unit......... Ward-L.......... EB... Do.
    ............................ Rod.............. H.R. steel, J"xl9-3/16" long—. Part of cord guard .................. SC-D-4256 assembly
    .........—.................. Seat, plug....... Phenolic-______________ Plug seat................................... SC-D-4251
    ............................ Sheet, duck—..... Cotton OD.............. Part of cord guard ................ ....	SC-D-4256 assembly
    ...-........................ Socket, lamp..... Switchboard..... Recall lamps................ W. E. Co._ 34.. SC-D-4249 ......-.............do...........do................................... Line and trunk lamps._do.....___ 47A....... Do. ...do......................................do.............. Cord circuit super- _____________do________do..........SC-D-4251 visory lamps
    Ref. Ref	Stock	_	. .	t, ..	...	Mfr’s, part Signal Corps
    fig. symbol	No.	Name	Description	Function	Mfr.	No	dwg. No.
    No.	______
    .......................do...................    -........ For resistor lamp in A. E. Co- D-9480. SC-D-4241 ringing circuit
    ......................... Spacer, key...... Left end of keyshelf................................. SC-D-4251 ........     do........................... Right end of keyshelf......................................... Do. ......................... Spacer. ........ Steel, used with magneto line  ............................... SC-D-4249
    circuit mounting plates
    ....................... Strip, designation, Brass.............. Designatio n strip ....-............. Do.
    plate	plate and drop re-
    tainer
    _________............_____ Strip, designation_ 6J"..._........._ Magneto lines..... W. E. Co.... 8M-..... Do. __________.__.____________ Strip, designation_ 7 J"....._......... Trunk, common bat- .do.... 8M-----. Do.
    tery line, through line, outgoing line, conference circuit and test circuit designation strips.
    .......................... Strip, terminal...................... Connecting block._ W. E. Co. 171C... SC-D-4266 .................... Strip, terminal.......... Phenolic.—.—. For use with cable ......................--- SC-D-4261 connector
    .......................... Strip, top............do.--------...... Top jack space.......------------. SC-D-4249 .............Support, cord weight Duck, OD—-----------............ Cord weight support .---------------— SC-D-4257 ................... Terminal..........-.............-- -.... Telephone a-c and .........do. 18A------- SC-D-4261
    d-c powerterminals
    .................. Unilet.......... Steel.............  -	Heating unit as- Appleton- 6625...... SC-D-4259 sembly
    ...........■_. ...................do............do..................  do................do... 9001-E.---- Do.
    ..........................do................do......................do............do..... 9200-LF—.. Do.
    ........................... Webbing___. Cotton, OD, wide.......--- Cable clamp...._..______........ SC-D-4251 .......   4C29100.......... Weight, cord_._ Flat, 8 to 11 oz...--- Cord weight.......___________......___ SC-D-4243
    74
    TM 11-340
    44	SIGNAL CORPS
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 44
    75
    c. Cabinet BE-79, main distributing frame.
    Ref.	Stock	_T	t-	Mfr’s, part Signal Corps
    tig. symbol	No.	Name	Description	Function	Mfr.	No_	dwg. No<
    No.
    _______________ 3E1298/1-1— Angle................................ Part of CD-298_ ____________________ SC-D-4287
    ............... 3Z756..... Binding post TM ...................... Cable connector, ___________________ SC-D-4289
    -197	cross-connection,
    and line terminals
    ............... 4E926_____ Block.......... Protector block...... Part of protector_ W. E. Co.... 26...
    .............. 4E927—..  ....do...............do......................do............do.... 27_________
    ......     ,______________ Clamp................................ Terminal strip clamp.._______________ SC-D-4274 .............. (3C161). (Coil C-161)............................ (Used with but not
    furnished as part
    of TC-2)
    ,.............. 3C476A........... Coil..... Heat coil............ Sneak current pre- .do... 76A........
    tection
    ............... 3E1298—..  Cord	CD-298.......................... Extends lines and ................... trunks to BD-89
    -A
    __________________________ Post........... Clamp post_________________ Terminal strip clamp __________ Do. post
    ............... 4E5368A___ Protector._____ Strip of 20... ............ Line protection..do. 1268A..... SC—D-4273
    .........................  Ring........... Distribution ring.......... Protection of cross-   ........ connection wires
    ...................       Strip........... Fanning strip, phenolic..—. Segregation of cross- ......... SC-D-4274 connection wires
    .......................      do........... Terminal, phenolic plate.. For line and trunk ............. SC-D-4284 binding posts
    ...................          do...............do_________________ For CD-298___....................... Do.
    .....................        do...... Phenolic, slotted ............do..  .       SC-D-4287 ...      do............................... Phenolic, cover....do...................................... Do.
    TM 11-340
    44
    SIGNAL CORPS
    I. Panel BD-98.

    Ref- Ref.	Stock	..	Mfr’s. P3rt Signal Corps
    fig- symbol	No.	Name	Description	Function	Mfr.	No.	dwg. No.
    No.	'	_________
    33 MAIN................... Circuit breaker._ 15-ampere, time delay Circuit breaker and Heine- 0322-15.. SC-D-5766
    curve D	switch	mann
    33 A & B, C, .............____do............ 10-ampere, timedelay ----do..............do... 0311-10.--- Do.
    & INT	curve D
    ..................... Ammeter._»_____ 20-0-20 amperes, d-c... Charge and dis- Weston..... 301.... Do.
    charge current
    ..................... Base........... Midget, flush, male... Telering and inter- Hubbell_ 7462..—	SC-D-4329 rupter output con-
    nection
    ........ 3Z209—...... Binding post TM- ..................... D-c power, 24 V C .................. Do.
    109	terminals
    .................. Block.......... Terminal, phenolic..—. For mounting d-c   ...............  SC-D-4403 power bus bars
    ............ ............. Busbar........ Copper.... D-c power bus bar............................. Do. .......................... Bushing. Phenolic, cord............ Thomas........ 70L................. SC—D—4329 ---------...	.do....................... Phenolic..—........ For binding post ........................ Do. -----... TM-109 .....................do................—	Phenolic, round-..... Part of Telering cord .............. Do.
    entrance bushing
    ................do............ Phenolic, diamond shape.........do................................ Do. ..................... Button......... Plug.................—	Closure plug, bottom United. E-512—.. Do.
    of Telering
    ......... Cap, plug ............................ Telering a-c power Hubbell_ 7238.... De.
    Plug
    ......... Coil .......__ Repeating...._.______ Ringing transformer.. W. E. Co.... 56A... Do. Cord assembly..__________.__________..._________ Ground cord----................. SC-D—6370
    ..............—...-.... Insulator...... Phenolic plate........ Rear cover plate for .............  —	SC-D-4403 d-c bus bar termi-
    nal strip
    Interrupter	______________________ D-c power ringer. W. E. Co..... 84F. SC-D-5766
    L.ZZZZZZ "Z".Z_2..... Plug........... 3-vire, flush base, male- D-c^power, (BAT Hubbell.. 7327.... SC-D-4329
    do. .	. • do................... D-c power, (24V-A) ..do.. 7808_______ Do.
    ...............;.....................     ’........or (24V-B) Receptacle. . Female....................................—-........ D-c power (BAT Crouse____ BR-2302... Do.
    ..................................... '	CABLE) do...................................do.....................  -.. D-c power, (SWBD __do________do...... De.
    .............................................. BAT CA) .......................... Receptacle housing..	....... D-c power, (BAT ....... do........... BRM—7302. Do. do...................................................■........... D-c power, (SWBD ..do........do....... Do.
    ................................................................   BAT.CA)
    76
    TM 11-340
    44
    TELEPHONE
    CENTRAL OFFICE SET TC-2
    .........-................. Ring, strain relief.-----------.................. Cord strain relief Ericson.:	Do.
    ring in Telering
    .............-............-	Telering............................... A-c power ringer. Telkor.. Model H	Do. (modified)
    ........................... Terminal block as- .................... D-c power bus bar ________________________ SC-D-4403 sembly.............................................terminal
    ........................... Terminal------- Copper tinned  ------- Frame ground termi- Stewart.... 311........ SC-D-4326
    nal
    —.............. 3Z10122—... Terminal TM—122._...................... Main circuit breaker...................... SC—D—4329
    —............ 3Z10126—..... Terminal TM-126....................... 24V A & B, 24V C, ................... Do.
    and I NT circuit breakers
    —.............. 3Z10130.... Terminal TM-130........................ Bus bar terminals....-...-.......... SC-D-4403
    ........................... Terminal............do—............... 24V C binding post Patton. 992A____________ SC-D-4329
    terminals
    ........................... Terminal..........do................... Terminals on Am- _do____ 2050....... Do .
    meter, BAT
    CABLE recepta-
    cle, and SWBD
    BAT CA recepta-
    cle
    .. ...........-............do— ...............do................... Voltmeter terminals  do.. 2053.......... Do. .................... Voltmeter................ 0-30	volts, d-c. D-c voltage-............... Weston.. 301.... Do.
    e. Cabinet BE-75, a-c power distribution.
    Ref.	Stock	_	,r, Mfr’s, part Signal Corps
    fig. symbol	No.	Name	Description	Function	Mfr.	No.	dwg No
    No.
    ..... 1	& 2; 3, 4, ........ Circuit breaker._ 25-ampere, time delay curve D A-c circuit pro- Heine- 0322-25..—	SC-D-4386 5 & 6; 7 & 8...............tection	mann
    ................. Outlet............-. Duplex	outlet......... Circuits 3 & 4, 5 & 6.. Hubbell_ 9575..... Do. ........................ Plug....... Flush.......base, female... Circuits 1, 2, 7 & 8.do__________ 8809..... Do. ........... Receptacle.............._..........	................ A-c power input—.... Crouse_____ BR-2302.. Do. ........................... Rec. housing.......................do..................... do_________ BRM-7302. Do.
    77
    TM 11-340
    44	SIGNAL CORPS
    f. Junction box JB-19.
    Ref.	Steck	_	. .	_	Mfr’s, part Signal Corps
    £S- symbol	No.	Name	Description	Function	Mfr.	No;	dwg. No.
    ............... 3Z756-..... Binding post TM- ..............................  ........................................ SC-D-4289
    197 ............................ 3able......... 2-conductor, rubber No. 8 24-volt, d-c power G. E. Co__________ 60% Type S..„ SC-D-4305
    AWG, 30 ' free length	cable
    ........................      do........... 2-conductcr rubber, No. 16 20-cycle a-c ringing .do.do................... Do. AWG, 30 ' free length	power cable
    ................................... Connector body. 10-ampere connector body. 20-cycle a-c ringing Hubbell. KX-11382_ Do. power cable con-
    nector
    ............................ Partition............. Phenolic______ Separate cable con- ________________________ Do. rectors
    ........................... Plug............................     24-volt	d-c power Crouse..... BP-8732-M3. Do. cable connector
    . ................................. Strip, terminal..do.........   For	mounting TM- ................................. Do.
    197
    g. Head and chest set HS-19.
    Ref' Ref.	Stock	.T	. .	_	Mfr’s, part Signal Corps
    fig- symbol	No.	Name	Description	Function	Mfr.	No	dwg. No.
    No. ............... 4B418.----- Chest unit T-26, in- ..i....................................................
    eludes the follow-
    ing items (Stock n umber i n p a-ren theses): ............... (4Z6924). Strap ST-24................................................................. ............... (4Z6925)..._ Strap ST-25.................._................................____________________... ............. (3Z8118)... Switch SW-118..... .................................................................... ............ 3E333....... Cord CC-333...... 6 3-conductor......................_.................................. ........... 3E337...__... Cord CC-337...... 20", 2-conductor.................................................._ ......... 4C4153BA....... Headband.............................................................................. . 4C4153BA/1________________ Pad......... Leather.....__........................................................ ............ 4B2358..... Plug PL-58............................... ............................. . ..... 4B2522......._______ Receiver R-22..................................._______..____________
    78
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 44
    79
    h. Rectifier RA-36-A, B, or C.
    Ref.	Stock	. .	„	Mfr’s, part Signal Corps
    Jig- ymbo	No.	Name	Description	Function	Mfr.	No.	dwg. No.
    No.
    .... ................... Ammeter...... 0-7 amperes......... Measures current................
    ........ 3H606...... Bulb......................     Rectifier.	....... G.E. Co. 189049...
    ....................... Capacitor.....	2 Uf............... A-c line filter. do.... 55X185.........
    ........... 3Z2015._.... Fuse......... 15 ampere, plug..  Output	circuit pro- ........._...
    tection
    ........................ Fuse block..........................—............  do.... 62965..........
    ........................ Switch....... Double pole, single throw, Control a-c and d-c _do. 235685.
    toggle switch	circu its
    TM 11-340
    44
    SIGNAL CORPS
    i. Maintenance equipment ME-6.
    Quantity Stoat No.	Name	Demotion	Mfr. Mfr^part	Cunts
    20	3E1298/1-1_ Angle............. .Spade terminal, cable connector.---------------------------- SC-D-4287
    20...... 3Z756—..... Rinding post TM-197-.............................        —.................    SC-D-4289
    1 ..... 6Z3150-1—... Body______________ Connector...................................... HubbelL. 7506-
    25 ..... 6L604-2N.. Bolt	.............. Machine, square head, steel, 1" x 2", 20 thread, nickeled..-----
    25...... 6L605-2.5N.. Bolt............. Machine, square head, steel, 5/16" x2£", 18 thread, .......... .
    nickeled
    25...... 6L606-2N... Bolt.............. Machine, square head, steel, 3/8" x 2", 16 thread, -------------
    nickeled
    10______ 6Z1727-.... Cap------------------------------------------------------- Hubbell_____________ 7057..
    3 ...... 6Z1734.1___ Cap, plug.....------------------------------------------------do.... 7238-------
    1....... 6Q19059____ Chest CH-59...............................    —.......................................
    1_______ 6Z3150..... Connector...—------------------------------------------------.do—.............. 7224...
    50 ft___ 3E1335/1—.. Cordage—.......... Rubber covered, black, 2-conductor No. 8 AWG.... G. E. Co_ 60% Type S.._.
    250 ft. 3E1395/1.... ..do.............. Rubber covered, black, 2-conductor No. 14 AWG...do.......do.
    1....... 3E1298....  Cord	CD-298...............................................................—......
    6	6Z5009.—___ Handle..—......... Carrying box, spare for CS-57, CS-63, CS-71, CS-73, Stanley. 1216...
    BE-79 and BD-89-A
    12 doz___ 6L3106-32.1 .. Nut__________ Brass, hex., No. 6-32, nickeled.-----------------------------
    12 doz___ 6L3108-32.1..—...do......... Brass, hex., No. 8-32, nickeled.................      -......
    12 doz__ 6L3110—32.1.. do............. Brass, hex., No. 10-32, nickeled................................... ..
    2 doz___ 6L3504-20.1.. do.............. Brass, hex., i", 20 thread, nickeled........................
    2 doz___ 6L3505-18.1—..do............. Brass, hex., 5/16", 18 thread, nickeled......................
    2 doz... 6L3506-16.1___do............. Brass, hex., 3/8", 16 thread, nickeled.......................
    1....... 6Z7564.______ Plug....................   ----------------------------- Crouse.— BP-8732-M3.
    12 doz__ 6L3112-24.1  Nut............. Brass, hex., No. 12-24, nickeled-----------------------------
    12 doz__ 6L6632-16.7._ Screw.......... Machine, FHB, nickeled, No. 6-32, 1"...................    —
    12 doz__ 6L6832-24.7.....do.....—..... Machine, FHB, nickeled, No. 8-32, lj"------------------------
    12 doz—.. 6L7032-24.7..„.do........... Machine, FHB, nickeled, No. 10-32, 1|".......................
    12 doz—.. 6L7224-32.7....do........... Machine, FHB, nickeled, No. 12-24,2".........................
    12 doz___ 6L8006-6.7—....do........... Wood, brass, flat head, i", No. 6, nickeled------------------
    12 doz... 6L8006-8.7...do............. Wood, brass, flat head, 1", No. 6, nickeled.... ..—..........
    12 doz.- 6L8008-6.7... do............. Wood, brass, flat head, f ", No. 8, nickeled.................
    12 doz__ 6L8008-8.7....do.........—... Wood, brass, flat head, 1", No. 8, nickeled------------------
    12 doz___ 6L8010-6.7__....do........—.. Wood, brass, flat head, No. 10, nickeled-------- -------------
    12 doz—.. 6L8010-8.7...do______________ Wood, brass, flat head, 1", No. 10, nickeled.------------------
    12 doz. 6L8010-12.7____do.............. Wood, brass, flat head, 1 J", No. 10, nickeled-.............
    10...... 6Z8363...  Socket............................................................. Hubbell.. 3595.
    1....... 6Q494.—.... Tool...........'._ Assembling....................................do- 3594........
    1000 ft.. IB 122-1—. Wire.............. Cross-connecting, No. 22 AWG, 2-conductor, black and Acorn—.—.
    red
    80
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 44
    j. Tool equipment TE-J^.
    Quantity Stock No.	Name	Description	Mfr. Mfrs, part Signal Corps
    ...........---------- '........................................................................No.	dwg. No. . 6Q8110-18---------- Blade................ Hacksaw, 10", 18 teeth per inch, flexible back...    .	_ _ 1.........-_ 6Q19058-_ Chest CH-58.................... ............
    3------- 6Q38030-6---------- File---------- Flat, bastard, 6".................................._.
    3-—6Q38030—10......... do.............. Flat, bastard, 10". ......................
    3------- 6Q38033-6-----do.............. Flat, second cut, 6"..._.......................
    3......- 6Q38033—10----do............. Flat, second cut, 10" ......
    3....... 6Q38500-10—.....do............ Round, bastard, 10"	_
    3-..... 6Q38500-6__ File TL-133........................... ....... .......... ZZZZZZ “ZZZZZZ
    }......- 6Q41000.---- Frame............ Hacksaw, adjustable 8" to 12"....;...	....................
    1........... 6Q49716........ Hammer..... Machinist’s, ball pein, 16—oz.....
    1.-......... 6Q50004.. do............... Riveting, cast steel, 4-oz..
    pr.... < J?56/L1... Lead, test	.......................................... Weston..'”.".' ' 5-70033-4”-”.
    1...... 6Z7496-------------- Padlock MC-96 Type
    la	............ ” .......................................
    ......	... Plie5s.......-... Spring adjusting....................... Klein.... 311......
    ...... 6R40313.......do............ Heat coil..................... do 313
    1........... 6R4513.... Pliers TL-13........	.	......... .... ..........
    2....... 6R4603..... Pliers TL-103___ ...	_ ....*.......... "	............... “..............
    1....... 6R4607....—	Pliers TL-107...........................    *................. ’............
    1.....— 6R4625..... Pliers TL-125.... ................~................................. ........
    1........... 6R4626. Pliers TL-126...............................................................
    1...... 6R19100............. Screwdriver set TL-128._........................ —”Z  ..............
    Consists of the follow-	....................
    ing quantity in paren-
    theses:
    (1).... 6R19030..... Screwdriver......:- Spiral ratchet...................... Yankee.. 30A__
    (8)...— 6Q34900..— Drill points.._____________ 1/16" to 11/64" and chuck. .
    (1).... 6Q29230........ Countersink..........................................
    (J).... 6R19011....... Screwdriver......... Ratchet, 6" blade..........Yankee”".”. 11^6 .
    (D....L 6R19015...... Screwdriver.......... Ratchet, 3 " blade............... ..do___15-3”'””””” ".
    1—..... 6R24008............. Shears.... Tinner’s hand snips, 8" over-all, 2" straight cut____
    1-.......... 6R24617........ Soldering iron TL-117.....................
    1------ 6R24512H.__.. Soldering iron ... Size 1J, j lb .with handle—............................
    1...6R24524H....... Soldering iron......... Size 3, 1J lb, with handle..........
    1—.......... 6R24620........ Soldering iron TL-120_________________......... '””  ..........
    2.................. 6R24641. Soldering iron holder.—............     ........ Vulcan ”..”” 2100...”
    1....--- 6R24617/1..... Tip.___________ For soldering iron TL-117.........
    1....------- 6R24620/1......do............. For soldering iron TL-120.....
    1........... 6R42167________ Torch TL-130.................        Z.....Z.ZZZ	ZZZZZZ." ZZ ........
    1........... 3F4056A/V1----- Volt-ohmmeter.... Type 3-B, 0-100,000 ohm,	0-300-600 v d-c...... Weston...	. Model 564
    1........... 6R55004. Wrench............ Adjustable, 4"............ Crescent* A-14
    2....... 6R55006 ... Wrench TL-111-..........  Z	..	... crescent. a h......
    1----------- 6R55010... Wrench TL-112-.......       ...;.....ZZZZZZZZZZ ZZZZZ7 ZZZZZZZZ”
    81
    TM 11-340
    44
    SIGNAL CORPS
    k. Switchboard plug cleaning material.— (Use with, but not included as a part of telephone central office set TC-2).
    Quantity Stock No.	Name	Description	Mfr. Mfr's, part Signal Corps
    No.	dwg. No.
    ....... 6G1315... Oil, light.....I 3-oz. can (“3 in 1”)..............................
    ....... 6G1516.... Polish, metal... Paste,	2-oz. can.................................
    ................. Rouge ......  Cake,	jeweler’s......................................
    82
    TM 11-340
    TELEPHONE CENTRAL OFFICE SET TC-2 45
    45. Addresses of manufacturers.
    Abbreviation	Name	Address
    Acorn ....		Acorn Insulated Wire Co. 		225 King St., Brooklyn, N. Y.
    A.E.Co. 		Automatic Electric Co.	1033 W. Van Burep St., Chicago, Ill.

    Appleton 		Appleton Electric Co. 		1701-20 Wellington Ave., Chicago, Ill.
    Crouse 			Crouse Hinds Co. 					Syracuse, N. Y.
    Ericson 			Ericson Manufacturing Co		Cleveland, Ohio
    G.E.Co.	...	General Electric Co.	Schenectady, N. Y. New York, N. Y. Trenton, N. J.
    Graybar 		Graybar Electric Co.
    Heinemann ..	Heinemann Electric Co.
    Hubbell 		Harvey Hubbell, Inc. 		Bridgeport, Conn.
    Patton 			Patton Macguyer Co.	Providence, R. I.
    Stanley		The Stanley Works	New Britain, Conn.
    Stewart 		Stewart Stamping Corp.	New York, N. Y. Elyria, Ohio Elizabeth, N. J. Cambridge, Mass. Lynn, Mass. Mount Vernon, N. Y. Kearny, N. J.
    Telkor 		Telkor, Inc. . . 	 .. ..
    Thomas 		Thomas & Betts Co. Inc.
    United 				United-Carr Fastener Corp.
    Vulcan 			Vulcan Electric Co.
    Ward-L 		Ward-Leonard Co
    W.E.Co.	Western Electric Co.
    Weston 		Weston Electrical
    	Instrument Co			Newark, N. J.
    [A. G. 062.11 (4-29-42).]
    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.)
    753—Ft. Monmouth—10-26-42—7M
    83