PANEL-MOUNTINGS

POST OFFICE ENGINEERING DEPARTMENT
TECHNICAL INSTRUCTIONS
TELEGRAPHS
GENERAL
D1001
Issue 1, September 1934

PANEL-MOUNTED TELEGRAPH
APPARATUS FOR PUBLIC CIRCUITS

General Instructions

1. Scope of Instruction
Panel-mounting is the standard method of accommodating telegraph apparatus used in conjunction with Public telegraph circuits, and this Instruction describes the panel-mounted apparatus installed in Telegraph Instrument Rooms at certain large offices.

2. General
Installations of the panel-mounted apparatus/are provided at the following Offices:-

London (C.T.O.), Aberdeen, Belfast, Birmingham, Brighton, Bristol, Cardiff, Derby, Manchester, Dundee, Edinburgh. Exeter, Glasgow, Inverness, Jersey, Leeds, Liverpool, Newcastle-on-Tyne, Nottingham, Plymouth, Sheffield and Southampton.

3. A complete installation comprises one or more of the following items:-

Apparatus Bay - accommodating 4 circuits.
Apparatus Bay - accommodating 14 circuits. (This is supplied in special circumstances).
Test Bay, with testing equipment for 8 circuits.
Concentrator.
Relay Test Panel.
Cord Test Panel.
Synchroscope Panel.
Observation and Test.
Teleprinter Test Pawl.
Intermediate Distribution Frame.

4. Assembly of panels
The panels which accommodate the telegraph apparatus and testing equipment are mounted on metal frames or racks, as described in paragraph 5. Three frames, fitted with panels, form a suite of bays for the equipment of 8 circuits. The central bay, designated Equipment, Telegraph D.9778 is is know the Test Bay; it is fitted with fuse and distribution panels and testing equipmentt. The two hrs installed one on either side of the Test Bay, designated Equipments, Telegraph D.9777, are known as Apparatus Bays; these bays carry apparatus and lamp panels. Diagram T.G.746 illustrates a complete suite of bays and shows the disposition of the various items of equipment whilst Diagram EC1531 shows in schematic form the layout of the equipment for 8 circuits mounted on a suite of three bays.

5. Dimensions and details of frames (or racks)
The frame employed for Equipment, Telegraph, D.9777/(Apparatus Bay) is described as Rack, Apparatus, No. 21A, and that employed for Equipment, Telegraph, D.9778 (Test Bay) is described as Rack, Apparatus, No. 21B. The dimensions of the frames are 6ft. 5in. x 1ft. 8.5in. The uprights of the frame comprise two lengths of mild-steel channel 3in. x 1.5in. x 5/16in. The 3in. faces of the uprights are tapped to take 3/8in. B.S.W. Hexagon-headed mild-steel bolts for securing the equipped panels. Similar bolts are employed to bolt individual frames together. The base comprises two pieces of angle 6in. x 7/16in., one mounted on the front and one on the rear of the frame, each being drilled 1/2in. clear for Lewis bolts for floor fixing. The top consists of a sheet of mild steel 1ft. 8.5in. x 3in. x 3/8in., which is screwed to the uprights. The inner surface of the uprights is lined with fibre to prevent damage to the cabling which is accommodate within the recess.

6. Diagrams
A list of Diagrams relating to the erection and wiring of the Panel-mounted equipment is contained in R1010.

POST OFFICE ENGINEERING DEPARTMENT
TECHNICAL INSTRUCTIONS
TELEGRAPHS
GENERAL
D1002
Issue 2, September 1935

PANED-MOUNTED TELEGRAPH
APPARATUS FOR PUBLIC CIRCUITS

Description of Equipment

1. General
The apparatus comprising various component parts of telegraph circuits is mounted on panels; details of individual equipment panels are given in D1001 et seq. The Apparatus and Testing panels are mounted on Racks, Apparatus No. 21A and 21B, as stated in D1001.

Two of the former (Apparatus Bay) are mounted - one on either side of one Rack Apparatus No. 21B (Test Bay); the 3 bays form a suite.

2. Apparatus Panels
These are designated Panels, Telegraph No. 1 to No. 5. The connexions of the apparatus and keys mounted on the panels are shown in schematic form in diagrams TG.767 to 770 inclusive. Each panel is provided with a series of four 3-position switching keys, mounted so that they are operated in pairs. These keys are employed to set up, as required, the following circuit conditions:-

With the key-levers in a horizontal position, the circuits are through.
With the key-levers of Keys 1 and 2 operated TEST SET TO LINE, the officer at the Test Bay is able to work to the distant station.
With the key-levers of Keys 1 and 2 operated to TEST SET TO LOCAL, the office at the test Bay is able to work to the local teleprinter position.
With the key-levers of Keys 3 and 4 operated to MORSE, the officer at the Test Bay is able to work to the distant station.
With the key-levers of Keys 3 and 4 operated to RESISTANCE, the battery, which is normally connected to line, is substituted by a lamp resistance. This condition is required when the circuit is being balanced for "duplex" working, see Paragraph 14.

3. Panels, Telegraph No. 2 to No. 5
These are provided with a 2-position switching key, labelled TELEPRINTER OFF. The function of this key is to disconnect the circuit between the tongue of the line relay and the local teleprinter position while testing operations are in progress. When the
key-lever is in the horizontal position, the circuit is "through" but when the key-lever is operated downwards to TELEPRINTER OFF, negative current is applied to teleprinter electromagnet, to hold the armature in the "rest" position.

4. Additional keys are provided on certain panels requiring exceptional facilities, as detailed below:-

Panel, Telegraph No. 1 - The "Teleprinter off" key is a 3-position switching key and when the key-lever is operated to SIGNALS RETURN, the connexion to the tongue of the line relay is diverted to the SEND line. This condition allows the Distant Station to receive its transmitted signals, repeated back from the line relay at the local (or receiving) station.
Panel, Telegraph No. 2 - A key is provided in the auxiliary circuit of the Relay, Standard, GN. When the key, lever is operated to "G" CIRCUIT OFF, the circuit between the tongue of the relay and/the auxiliary circuit is disconnected.
Panel, Telegraph No. 4 - A key is provided to enable the circuit conditions to be changed for "Simple" When the key lever is operated to SIMPLEX, the teleprinter contact tongue - when transmitting - is connected directly to the line circuit, under "Simplex" conditions.

5. Test Bay
Rack Apparatus No. 21B is employed to accommodate the Panels, Telegraph Nos. 6, 7 and 8 and other testing equipment comprising the Test Bay.

6. The Test Bay Jack Field
Panels, Telegraph Nos. 6 and 7 consist of eight jack strips. The jacks are arranged in double rows of 20 jacks each. Each of tie eight Teleprinter Sets associated with a Test Bay is allocated twelve double jacks and' these are located at the left-hand end of the jack strips. The position of these jacks is uniform for each set - irrespective of the type of panel in use. Numbering from the left-hand side of the Jack-strips, Jack No. 1 is in circuit between the centre-tap lead from the separate battery and he Set tag strip. Jack 2 is in circuit between the A-wire and the line relay of the Set; Jack 3, between the B-wire and the Set tag-strip; Jack 4, between the line relay tongue and the teleprinter electromagnet; Jack 5, between the teleprinter electromagnet and the shunted condenser; Jack 6, between the teleprinter contact-tongue and the line milliammeter of the Set; Jack 7, between the negative line battery and the switching keys of the Set; Jack 8, between the positive line battery and the switching-keys of the set; Jack 9, between the negative local battery and the "marking" contact of the line relay; Jack 10, between the positive local battery and the "spacing" contact of the line relay. Where sets for 2-Way Simplex working are installed, Jack 11 is in the circuit of the SEND A-wire and Jack 12 in the circuit of the SEND B-wire. Certain of the jacks /located at the right-hand end of the jack strips are inserted in the circuit of the testing apparatus. Jack 19, Jack Strip No. 2, is in circuit between an 80-volt negative battery and the set tag-strips, for use in connexion with the test teleprinter. Jack 20, Jack Strip No. 2, is similarly placed in the positive lead of the test teleprinter battery. Jack 19, Jack Strip No. 3, is in circuit between the "M" contact of the "leak" relay and the 80-volt negative battery. Jack 20, Jack Strip No. 3, similary placed in the positive lead to "5" of the "leak" relay. Jack 16, Jack Strip No. 7, is in circuit between the electromagnet of the test teleprinter and its shunted condenser. Jack 17 is in circuit between the test teleprinter electromagnet and earth; Jack 18, between the battery and the "M" contact of the test teleprinter; Jack 19, between the tongue of the test teleprinter and the set rags; Jack 20, between the battery and "5" contact of the test teleprinter. On Jack Strip No. 8 Jack 16 is in circuit between the right-hand front terminal of the Morse key and the set tags; Jack 17, Jack Strip No. 8, between the back terminal of the Morse key and the set tags; Jack 18, between the left-hand front terminal of the Morse key and the set tags; Jack 19, between the set tags and the polarized sounder; Jack 20, between the shunted condenser of the polarized sounder and earth.

7. By means of the jack field, tests may be made of lines, batteries and local circuits.

8. Testing Apparatus.
The following testing apparatus is mounted on the Test Bay:-

A 150-0-150 (centre-zero) voltmeter.
A 3-hole Voltmeter Test Tablet, for use in conjunction with Item (a).
A 7-hole Test Tablet, for line and local tests.
A Fuse Mounting No. 107 and a Lamp, No. 2-40 volt, forming a circuit for testing the fuses and cords.
A Relay, Standard, BN, with Baseboard No. 26—used in the "outgoing" leak circuit.
A Milliammeter No. 17 (connected in the line coils circuit of the Relay, Standard, BN).
A Milliammeter No. 17, for use in conjunction with Item (c).
A Jack No. 44, for use with the Test Teleprinter.
A socket for Plug, Wall No. 2B (for the Test Teleprinter Motor).
A Switch, Tumbler, No. 9 (connected in power leads to Test Teleprinter Motor).
A Coil, Shunt, (connected in the line coils circuit of the "leak" relay).
Eight Keys No. 68 (one Key is connected in the "outgoing" leak circuit of each set).
Eight keys No. 68 (one Key is connected in the "incoming" leak circuit of each set).
A Key No. 68, used as a master key to control the incoming and outgoing leak circuits.
A Jack No. 501 AN, for use where telephone facilities are required. Small brackets attached to the Panel, Telegraph No. 8, accommodate a Key, S.C. and a Sounder, Polarized, D.2000ohms. The wiring of the apparatus mounted on Panels, Telegraph Nos. 6, 7 and 8, is shown in diagram TG.741; the layout of the equipment is shown in diagram TG.766, whilst diagram EC.1491 shows the labelling. Instructions contained in D5001 detail the method to be adopted to carry out various tests proper to the Test Bay.

9. Power Supplies
Power Supplies for line and local batteries, and for certain other circuits used in conjunction with a suite of bays, are provided by means of fuse panels, fitted on the lower part of the Test Bay.

10. Panel, Telegraph, No. 9
This is employed for the universal battery supply of ±24, 40, 80 and 120 volts. The power leads are connected to soldering sockets at the rear of each of the eight bus-bars. Four bus-bars on the right-hand side of the panel are for the positive supplies; similarly, four bus-bars on the left-hand side are for the negative supplies. Ten clips, to hold Fuses No. 1/1 are attached to the 40-volt and 80-volt bus-bars. Five clips are attached to the 24-volt and 120-volt bus-bars To provide a means of changing the value of the line battery, holes - arranged in half circles - are drilled in the panel. On the positive side of the panel, eight groups of four holes - arranged in half-circles - are drilled in the panel. Each of the positive powers is connected to one of these holes. A hole drilled centrally with the arc is connected to a line battery lamp resistance on a Panel, Telegraph No. 11. Similar arrangements are provided on the negative side of the Panel. A U-link has one side anchored to the central hole, whilst the other side may be inserted, as required, into any one of the four holes, referred to above. Thus, any one of the four battery powers may be connected to a set, by suitably adjusting a U-link. The 24-volt and 120-volt batteries are shared by two adjacent set links, so that there is full availability of 40-volt and 80-volt supply but only half availability of the 24-volt and the 120-volt supplies.

11. The wiring for line and local batteries from the Panel, Telegraph No. 9 is extended in a cable to the upper part of the Test Bay, where the free ends are coiled. The leads are "tapped out" at the Office where the equipment is installed, and connected to the relative jacks on the lamp panels. From the lamp panel, the power leads pass through the wiring of the tag strips to the jack field on the Test Bay.

12. Panel, Telegraph No. 10
A Panel, Telegraph No. 10 is used for the 80-volt ± universal supply for the local circuits of the line relay and the line battery supply, where a separate line battery for a metallic loop circuit is employed. Two bus-bars are provided, each with positions for ten fuses, to which the positive and negative universal battery terminals are connected. Eight groups of 3 fuse-mountings are fixed for positive, negative, and centre-point leads of the separate batteries.

13. Panel, Telegraph No. 11 (Lamp Panels)
A Panel, Telegraph No. 11 is provided on each Apparatus and Test Bay. The panel fitted on the left-hand apparatus bay is fitted with 12 Jacks, Lamp, No. 12 to accommodate Lamps, Glow, for the line and local battery leads, serving Sets 1-3, four lamps are used for each set. The panel fitted on the Test Bay is fitted with 12 jacks to accommodate the lamps for Sets 4 and 5, also the lamps connected in the 80-volt leads from the battery to the Leak Relay and Test Teleprinter. The panel fitted on the right-hand apparatus bay is fitted with 12 jacks for Lamps, Glow, associated with Sets 6-8. Lamps, Glow, 16 c.p., 100-volt, E.S. are usually employed for the line and local circuits but, in exceptional circumstances, Lamps, Glow, 32 c.p., 100-volt, E.S. may be required.

14. Panel, Telegraph No. 12
This is fitted at the rear of each Panel, Telegraph No. 11. This panel is fitted with 3 Jacks, Lamp No. 12, to accommodate the lamps required when a distant station is fixing the artificial line balance for a duplex circuit, as referred to in paragraph 2 (e).

15. The general scheme of wiring for the apparatus associated with a Teleprinter Circuit accommodated on a suite of bays is shown in schematic form in diagram TG.766. Reference to this diagram in conjunction with the relative schematic diagram for the individual Panel, Telegraph concerned - Diagrams TG.767 to TG.770 inclusive - will enable the connexions to be traced for any position of the key-levers of the switching-keys mounted on the Apparatus or Test Bay Panels.

16. Concentrator
This provides facilities for concentrating circuits on the instrument side. A jack field is arranged in multiples of 20, to a maximum of 100 jacks. The equipment is mounted on Rack, Apparatus No. 21C and is installed in close proximity to the other panel-mounted equipment. Six-point jacks - Jacks No. 49 - are arranged in double rows of 20; the upper row of jacks are used for LINE jacks and the lower row for INSTRUMENT Jacks. The entrance to each jack is rounded at the upper end, to prevent the insertion of a reversed plug.

17. On the "line" side jacks, the long springs are connected to the panel-mounted apparatus as follows:-

Line Battery positive, see "S" Diagram TG.748.
Line Battery negative, see "M" Diagram TG.748.
"Line" Milliammeter, see "T" Diagram TG.748.
Tongue of Line Relay, see "R" Diagram TG.748.
Shunted Condenser of teleprinter electromagnet circuit, see "E "in diagram TG.748.

The sixth long spring is wired to the I.D.F. for use subsequently, as required.

18. On the "Instrument" side jacks, the long springs are connected as follows:-

Teleprinter spacing contact, see "S" Diagram TG.748.
Teleprinter marking contact, see "M" Diagram TG.748.
Teleprinter contact-tongue, see "T" Diagram TG.748.
Teleprinter electromagnet coils, see "R" Diagram TG.748.
Teleprinter electromagnet coils, Return lead, see "E" of diagram TG.748.

19. The arrangement described in paragraph 17 and 18 permits the line side of any circuit to be connected to any instrument table position, irrespective of the type of panel, and with only a momentary disturbance of transmission.

20. For transfer purposes, Plugs No. 607 - fitted with Cord No. 618 - are used; they are of the flat-spring type, three springs being mounted oil either side of an insulating plate. Labels No. 177 are used for labelling the jacks. The labels of the upper row are engraved with the circuit designation and the lower row, with the Teleprinter position number.

21. Panel, Telegraph No. 21
A Relay Test Panel - Panel, Telegraph No. 21 - is usually mounted above the jack field on the Concentrator. (This panel is fully described in P.W.'s and Telex, C.1136, whilst the facilities provided by the panel and the method of operating it are described in P.W.'s and Telex, C5124. Instructions for cleaning Relays, Standard, BN, GN and HN are contained in P.W.'s and Telex C5125.)

22. Panel, Telegraph No. 33
This is mounted on the upper part of the Concentrator; it provides facilities for testing Plugs No. 607 fitted with Cord No. 618. The associated apparatus consists of two Jacks No. 49, Milliammeter No. 20 and a Resistor, Coil No. 12-10,000ohms.

When plugs are inserted into the jacks, a 24-volt positive battery is applied through the resistor, the milliammeter, and each spring of the plugs, in series, to earth. Continuity of the cord is shown by a deflection on the milliammeter needle. The panel also bears two Jacks No. 49, to provide transfer facilities from the line side of any circuit on the Concentrator to a Teleprinter Test Position. This facility is employed when a distant office requires attention for a lengthy period; it relieves the Testing Officer at the Test Bay, who may be required upon other Sets. (The Teleprinter Test Panel is described in paragraph 33.)

23. Panel, Telegraph No. 34
This panel is installed at certain Telegraph Offices for the purpose of testing the speed of teleprinter motors. The unit comprises a mains transformer, from which a 10-pole synchronous motor is driven at a speed of 600rpm. The motor spindle is fitted with two gear wheels, one of which is used when Teleprinter No. 3A is being tested and the other, for testing Teleprinter No. 7A or No. 7B.

24. Operation of the Synchroscope
A brush carrier is fitted with two brushes, which rotate upon two metal rings; one of these rings is solid and the other is divided into 12 equal segments, insulated from each other and from the solid ring. The carrier engages with a gear wheel, which is coupled to one of the gear wheels on the motor spindle. Connected in parallel with six alternate segments are six Lamps No. 13 - 220volts. One side of the lamps is commoned and connected to the contacts of a Relay No. 502A. One of the output terminals of the mains transformer is connected to the solid ring and the other to the local circuit of the Relay No. 502A. If, therefore, the local circuit of the relay is closed and the brushes rotate, certain lamps will glow at each revolution. A starter button is provided on the brush carrier.

25. A Relay, Standard, BN, is mounted on the Panel, No. 1 terminal of the line coils is connected to a Jack No. 501 BO and No. 4 terminal, to earth, through a resistor of 4,000ohms, shunted by a 2uF condenser. An 80-volt positive battery is connected through a resistor of 1,000ohms to the tongue of this relay. The spacing contact of this relay is connected to earth, via the coils of the Relay No. 502A.

26. To check the speed of a Teleprinter motor the letter "V" is transmitted continuously by the teleprinter under test; (this signal consists of five consecutive "marking" and two consecutive "spacing" units). The lead from the teleprinter teleprinter contact-tongue is connected by means of a cord to the Jack No. 501 B.O. The reception of signals from the teleprinter under test, results in a beat of the relay tongue and the operation of Relay No. No. 502A for each revolution of the transmitting cam-sleeve. If these beats bear the right relationship to the revolution of the spindle of the synchronous motor the same lamp, or lamps, will glow at each revolution of the brushes, but, if the beats gain on, or fall away from the speed of the brushes, the difference will be indicated by the glow of the lamps shifting in a clockwise direction if the teleprinter is running slow and in an anti-clockwise direction if it is running fast. Engraved plates, affixed to the Panel, enable any discrepancy in speed to be calculated on a percentage basis. The percentage variation from standard speed is determined by noting the time taken for the circle of lamps to glow, each rotation, in conjunction with the table of values attached to the Panel. As a means of ascertaining correctly the time taken, a half minute impulse clock circuit, served from a master clock, is provided. A lamp flashes at intervals of half a minute when the circuit is closed by means of a key-switch on the panel.

27. Panels, Telegraph No. 38 and No. 39
These panels are installed at the Central Telegraph Office, London, and at certain large Provincial telegraph offices. They accommodate short 2-way "Simplex" circuits and are mounted on a Rack, Apparatus No. 21. Full details of these panels are given in D1028, D1029 and D1033.

28. Panel, Telegraph No. 39
This is an apparatus panel equipped for two circuits; seven of these panels are mounted together with one Panel, Telegraph No. 38, which provides testing and monitoring facilities. A connexion strip is mounted on each Panel, Telegraph No. 29, by means of which the conditions may be arranged to meet the requirements of:-

A non-relayed circuit (See Fig. 1 of Diagram TG.873).
A circuit with the Head Office relay biased by means of a current (see Fig. 2 of Diagram TG.873).
A circuit with the Head Office relay biased by mechanical means (see Fig. 3 of Diagram TG.873).

A Resistor, Coil No. 16 is connected in the circuit of the "Receive" line and this should be adjusted to allow a current of 20mA. A Resistor, Coil, No. 16 is also connected in circuit with one of the line relay coils when a circuit of the type referred to in paragraph 28 (b) is accommodated on the Panel. This resistor should be adjusted to allow a current of 15mA in the biasing coil of the relay.

29. Panel, Telegraph No. 38
Each of he 14 circuits accommodated on the Panel is connected to a group of 3 jacks on a jack-strip. These jacks are designated respectively SEND LOCAL and RECEIVE, and are arranged so that the individual jacks associated with each circuit are vertically adjacent to each other. The uppermost jack - the SEND jack - is connected between the SEND line and the tongue of the teleprinter at the Head Office. The middle - LOCAL - jack is connected between the tongue of the line relay and the teleprinter electromagnet. (In the case of a circuit of the type referred to in paragraph 28 (a), this jack is connected in the RECEIVE line). The lower jack - RECEIVE jack - is connected between the line coils of the relay and the RECEIVE line.

30. Two Milliammeters No. 20 are connected to Jacks Nos. 19 and 20 respectively on the jack strip; by means of plugs and cord, a connexion to any one of the SEND, LOCAL or RECEIVE jacks may be made for observation purposes. In this connexion, it is important to insert the plug into the milliammeter jack first; this prevents a momentary disconnexion of the circuit concerned.

31. Observation and Test Set (Tester TG.803)
This tester is described in Multi-Channel V.F., B3001. A Jack No. 44 and a Socket and Switch for Plug, Wall, No. 8 are mounted on the test panel to enable the Tester, TG., No. 803 to be used. The SEND and RECEIVE jacks of the Tester are patched to the SEND and LOCAL jacks of the circuit on the Panel, Telegraph, No. 38 when required for testing purposes. (The RECEIVE jack of the circuit is not used for this operation). The circuit conditions which may be set up by means of the Tester TG. 803 are detailed in D5002.

32. Power for circuits accommodated on Panels, Telegraph No. 39
This is standardised at 80-volts and is served from the Power Board described in Multi-Chanel V.F. B3001. The leads from the Power Board are run to the Intermediate Distribution Frame, 2nd vertical, front; from the rear of the 2nd vertical, the leads are taken to the "power" Strip, Connexion, on the Equipment, Telegraph D60093 (Diagram TG.873). The shunted condensers for the teleprinter electromagnet circuits are mounted on the Power Board, connexions being made from the "E" connexion on the "power" strip of the equipment.

33. Teleprinter Test Panel
A Panel, Telegraph No. 18 - diagram TG.744 - is provided to enable Teleprinters No. 3A to be tested and adjusted in the Instrument Room. The panel may be mounted on a table provided locally, or at a bench position. Mounted on the panel are a Milliammeter No. 17, a Rheostat "R" and a Rheostat "S" - connected in series - and three switching-keys, labelled to indicate their functions. The panel is connected to two Jacks No. 49 on the Panel, Telegraph, No. 33, mounted above the Concentrator jack field. The power required for testing is 24 volts ±, and is supplied from Panel, Telegraph No. 9 at the Test Bay, via the line side jack. The earth lead for the Panel is obtained from the Test Bay, also via the line side jack. Three Jacks No. 44 - labelled respectively "A" TROLLEY JACK, "B" TEST JACK and "C" LINE JACK - should be fitted, together with two Sockets and Switches for Plug, Wall No. 8 and one Box, Service, E.L. No. 0, on the table or bench which accommodates the Teleprinter Test Panel. A typical layout for this equipment is shown n Diagram TG.744. The method of carrying out various tests as required on the Teleprinter Test Panel is detailed in D5003.

34. Intermediate Distribution Frame
A standard I.D.F. Diagram EC.1533, TG.833 is provided. It consists of 2 or 3 verticals, each/vertical can accommodate 8 Strips, Connexion No. 41A fitted on the front and on the back. This number will provide sufficient tags for the largest Offices; the strips should be requisitioned separately according to local requirements. The allocation of connexions to the verticals is detailed in P3002.

35. External Wiring of Panel Equipment
This work is carried out locally as specified in D3001.

36. Wiring of Instrument Table Position
The apparatus associated with the SEND and RECEIVE circuits is mounted on the trap covers, on the Instrument Table for Teleprinters No. 3A. Full details of this apparatus and its wiring are shown on Diagrams Misc. 4296 and TG.827.

POST OFFICE ENGINEERING DEPARTMENT
TECHNICAL INSTRUCTIONS
TELEGRAPHS
GENERAL
D3001
Issue 1, September 1934

PANEL-MOUNTED TELEGRAPH APPARATUS
FOR PUBLIC CIRCUITS

Installation of Equipment

1. Scope of Instruction
This Instruction details the work to be performed by the engineering staff in connexion with the installation of the panel-mounted equipment employed for public telegraph circuits. A general description of this equipment is given in D1001.

2. Erection of equipment
The position allotted to the panel-mounted equipment in the Instrument Room is determined by the Telegraph and Telephone Department (Traffic Section), who furnish plans to the Engineer-in-Chief. H.M. Office of Works should be consulted by the Superintending Engineer of the District concerned, to ascertain whether, having regard to the total weight of the equipment, structural alterations or floor strengthening will be required. In this connexion, it should be noted that the total weight of one suite of bays, i.e., two Apparatus Bays and one Test Bay, is approximately 8cwt. (or 1cwt. 2qrs. per foot run). Wherever possible, a concrete base should be provided, to which the frames will be secured by means of Lewis bolts. A typical example of the method of erection and fitting of frames is shown in Diagram EC1532.

3. The type of panels required for individual issues of "Equipments, Telegraph," and their position on the frames is decided by the Telegraph and Telephone Department, who furnish a plan for the. layout of the panels and the disposition of the equipment for individual circuits. In allocating panel positions, consideration is given:-

To the requirements of spare and reserve positions, in order to distribute them over the whole equipment and thus to equalize the load of the working circuits on each Test Bay.
To avoid having all the circuits serving two centres on one particular suite.
To arrange for the equipment associated with circuits requiring close attention to be placed in the most favourable position, i.e., at a convenient height. For this reason panel No. 2 will be given the "set 2" position, as shown in Diagram EC1551,

4. Equipment to be requisitioned
When an estimate for an installation has been authorized, one or more suites of bays should be requisitioned as required. The items required for one suite are as detailed below:-

1 x Equipment, Telegraph, D 9778 (Test Bay, fully equipped and wired).
2 x Equipment, Telegraph, D 9777 (Apparatus Bays - fully equipped and wired - each with 4 Panels, Telegraph, No. 1-5 as specified).

The following additional items will be required for one suite; these should be requisitioned separately:-

Relays, Standard, BN or GN - as required.
1 x Cap, Lamp, No. 2.
50 x Fuses No. 1/1.
1 x Guard Rail for panels.
45 x Lamps, Glow, 100V., E.S., 16 c.p. or 32 c.p., as required.
1 x Lamp No. 2, 4-volt.
1 x Lamp No. 2, 40-volt.
1 x Voltmeter No. 27 (portable voltmeter, for balancing duplex circuits).
6 x Pegs No. 16, Green.
10 x Plugs, No. 121, fitted with Cord, Instrument, No. 104
1 x Coil, Induction, No. 14 and 1 x Condenser, M.C., No. 102 are required for a telephone circuit. To be fitted locally in place of the centre Resistance Lamp on "Equipments, Telegraph D 9778".
6 x Bolts, 3/8in. B.S.W. x 1 in. Hexagonal Head, Mild Steel, Blued or Lacquered (for bolting individual bays together).
12 x Lewis bolts (as required - for fixing one suite to the floor).

5. Panels
Individual panels will be provided for particular circuit requirements as specified by the Telegraph and Telephone Department (Traffic Section). The various types of panel, and the type of circuit for which they are appropriate, are detailed below. Any one of these panels can be obtained on requisition, if at any time it is required to change the type of circuit to be accommodated on existing equipment.

Panel, Dummy, No. 1 - (For vacant positions on Apparatus Bays, if required).
Panel, Telegraph, No. 1 - Diagrams TG 734, TG 767 (for 2-way simplex teleprinter circuit)
Panel, Telegraph, No. 2 - Diagrams TG 735, TG 768 (for loop or single-wire duplex teleprinter circuit, using a vibrating type relay).
Panel, Telegraph, No. 3 - Diagrams TG 736, TG 768 (for loop or single-wire duplex teleprinter circuit, using a Relay, Standard, BN).
Panel, Telegraph, No. 4 - Diagrams TG 745, TG 769 (for loop or single-wire duplex or Special Event simplex teleprinter circuit).
Panel, Telegraph, No. 5 - Diagrams TG 747, TG 770 (for 2-line simplex teleprinter circuit - C, B system).
Panel, Telegraph, No. 6 - Used in conjunction on the Test Bay, see Diagram TG 741.
Panel, Telegraph, No. 7 - Used in conjunction on the Test Bay, see Diagram TG 741.
Panel, Telegraph, No. 8 - Used in conjunction on the Test Bay, see Diagram TG 741.
Panel, Telegraph, No. 9 - Diagram TG 743 (Fuse and. Distribution panel for Universal Line batteries).
Panel, Telegraph, No. 10 - Diagram TG 742 (Fuse and Distribution panel for Loop batteries and for Local Line batteries).
Panel, Telegraph, No. 11 - (Lamp panel for 12 Battery Resistance lamps).
Panel, Telegraph, No. 12 - Diagram TG 737 (Lamp panel for three Battery Resistance lamps).
Panel, Telegraph, No. 18 - Diagram TG 744 (Test panel for Teleprinters No. 3A).
Panel, Telegraph, No. 21 - Diagrams TG 801, 750. (Test panel for Telegraph Relays - see P.W.s & Telex, C1136).
Panel, Telegraph, No. 23 - Diagram EC 1551 (Fuse and Distribution panel).
Panel, Telegraph, No. 24 - Diagram EC 1551 (Alarm panel for use with "Panel, Telegraph, No. 23").
Panel, Telegraph, No. 33 - (Cord Test for Concentrator Plugs and Cords).
Panel, Telegraph, No. 34 - Diagram TG 865 (Synchroscope for testing speed of Teleprinters No. 3A; where authorized by Headquarters).
Panel, Telegraph, No. 38 - (Monitor and Test panel for L.P.S. circuits accommodated on No. 39.
Panel, Telegraph, No. 39 - (Accommodates 2 L.P.S. circuits).

Click here for a typical example of one suite comprising of 2 apparatus bays and 1 test bay - Drawing TG746

PANELS, TELEGRAPH

A detailed description of each of these panels is given in the series of Engineering Instructions, Telegraphs, General D1010 to D1129.
D1011 - Panel, Telegraph No. 1.
D1012 - Panel, Telegraph No. 2.
D1013 - Panel, Telegraph No. 3.
D1014 - Panel, Telegraph No. 4.
D1015 - Panel, Telegraph No. 5.
D1016 - Panel, Telegraph No. 6.
D1017 - Panel, Telegraph No. 7.
D1018 - Panel, Telegraph No. 8.
D1019 - Panel, Telegraph No. 9.
D1020 - Panel, Telegraph No. 10.
D1021 - Panel, Telegraph No. 11.
D1023 - Panel, Telegraph No. 18.
D1026 - Panel, Telegraph No. 33.
D1029 - Panel, Telegraph No. 39.