HES No. 3


TELECOMMUNICATIONS INSTRUCTION
C MARKETING
INSTALLATION
3 Internal
C3030
Issue 2, Aug 1973

THE HOUSE EXCHANGE SYSTEM No. 3
Facilities

1 GENERAL
This Instruction describes the facilities provided in a House Exchange System No. 3 (HES No. 3) which has been given the sales name of 'Keymaster'. This system provides intercommunication between a maximum of five stations with direct access from these stations to an exchange line.

2 DEFINITIONS

  • Multiple station A multiple station is one equipped with a Telephone, Intercom, No. 3/1 (F or CB) which is a 700 type instrument. Multiple stations are linked by multiple cable and are normally confined to one building but the multiple may be extended to link stations in a nearby building if signalling limits are not exceeded.
  • Non-multiple extension This is an extension station which is equipped with a Telephone No. 710 (F or CB); it is connected to the multiple by a two-wire line and a relay-unit.
  • Main station This is the multiple station where incoming exchange calls always give an audible signal, and which assists the non-multiple extension with calls to other stations. The main station also controls soon of the additional facilities which may be added to the system.

3 CAPACITY OF INSTALLATION
A HES No. 3 comprises one exchange line and up to five stations. One non-multiple extension may be connected in place of the last multiple station, and stations may also be replaced by private circuits to another house exchange system or a PBX. The system also includes one or two relay-units and a Power-unit No. 51A; all these units are wall-mounted.

4 EXCHANGE CALLS
The HES No. 3 works on CB principles but may be connected to any type of public exchange. In LB areas an auxiliary unit must be fitted at the exchange to provide the required CB conditions.

The HES No. 3 is unsuitable for shared service.

Exchange service is available from any station including the non-multiple extension. Access to the exchange line is by a locking press-button with gravity switch restoration. Exchange calls are secret. Calls may be held by any station and transferred to any other station.

Incoming exchange calls normally ring a standard magneto bell mounted inside the Telephone, Intercom, No. 3/1 at each multiple station but they do not ring a bell at the non-multiple extension except for night service. Each Telephone, Intercom, No. 3/1 is fitted with a bell cut-off key. This key is made inoperative at the main station to ensure that at least one bell of the installation can be rung by incoming exchange calls. If the exchange ringing supply is sub-standard, e.g. from a vibrator, it may not be possible to ring all bells simultaneously and one or two may have to be permanently short-circuited.

5 INTERCOM CALLS
A multiple station can call any other station by means of a non-locking press-button. The non-multiple extension cannot call multiple stations directly and relies on the main station to signal the required station.

Buzzer tone is returned to the non-multiple extension as an indication that the main station is being called. Intercom calls are signalled at multiple stations by buzzer and at the non-multiple extension by magneto bell.

The intercom speech circuit is common to all stations, thus intercom calls are not secret. At multiple stations automatic connection to the intercom circuit is made when the handset is lifted but at the non-multiple extension the EXTN button must also be pressed.

6 CONFERENCE CALLS
All stations can be called in to a local conference by signalling each in turn. Conference facilities are not available on exchange calls.

7 LAMP SIGNALS
Telephones, Intercom, No. 3/1 are fitted with two MES bulbs. A red lamp signal indicates that the exchange line is engaged and warns other stations not to operate the exchange button as this interrupts the exchange line circuit. This lamp glows in rhythm with the ringing current on incoming exchange calls but is not intended to be a general calling signal. This lamp also flickers when an exchange call is held, e.g. while arranging for the transfer of the call to another station.

A white lamp signal is given when the intercom circuit is in use to warn stations wishing to use this circuit not to interrupt a call in progress unnecessarily.

8 EXTENSION ENGAGED SIGNAL
A multiple station which attempts to call an engaged station operates its own buzzer.

9 NIGHT SERVICE
The non-multiple extension may be given night service on incoming exchange calls by means of switching provided at the main station. Under this condition incoming exchange calls will ring the non-multiple extension bell as well as the bells at multiple stations but, to ensure that the number of bells does not exceed that which can be rung by the exchange, it is desirable to cut off bells which are not required.

Outgoing exchange service continues to be available at all stations and intercom calls are not affected by night service conditions.

10 ASSOCIATION WITH A PBX
A HES No. 3 installation may be associated with a PBX in several ways.

  • An extension from a PBX may be terminated on the exchange line connection at the HES No. 3 installation. All the facilities available to PBX extensions, including operator recall, are also available to HES No. 3 stations.
  • Subject to satisfactory transmission, the HES No. 3 non-multiple extension may be terminated as an exchange line or private circuit on the distant switchboard. Exchange calls cannot be extended in either direction.
  • A Relay-unit Q415, fitted in place of a multiple station, will usually provide all normal interswitchboard facilities between a HES No. 3 and a PBX.

11 HOUSE EXCHANGE FACILITIES BETWEEN PBX EXTENSIONS
Individual PBX extensions may be-terminated on the HES No. 3 so that each station there has an exclusive line to the PBX in place of direct exchange line access. Local intercom, calls can be made between stations , but access to exchange service or other PBX extensions must be obtained via the PBX. Transfer of exchange calls must be made via the PBX.

12 ASSOCIATION OF HES NO. 3 WITH OTHER HOUSE EXCHANGE INSTALLATIONS

  • The non-multiple extension of the HES No. 3 may be connected to an exchange line position of HES Nos. 1, 2 or 4. Exchange calls cannot be extended in either direction.
  • The non-multiple extension of HES Nos. 1 or 2 may be connected as the exchange line of the HES No. 3. Subject to satisfactory transmission and signalling, exchange calls can be extended to the HES No. 3.
  • Using a suitable Relay Unit in place of a multiple station the HES No. 3 may be connected to an exchange line or non-multiple position of an HES No. 1 or 2; use of the latter position allows exchange calls to be extended to the HES No. 3.
  • Two HES No. 3 systems can be connected together by a private circuit using Relay-.units Q415 at each installation in place of a multiple station. Exchange calls can be extended in one direction only.
  • An HES No. 3 installation may be connected using suitable relay units in place of multiple stations to an HES No. 4 installation. Exchange calls can be extended in one direction only.

13 EXTENSION PLANS
Plan arrangements similar to Extension Plans 1... and 107 can be provided at the non-multiple extension. Extension plans cannot be provided at multiple stations.

14 EXTENSION BELLS AND BUZZERS
Extension a.c. bells may be connected in addition to or in place of. the existing magneto bell at all stations. Extension d.c. bells or buzzers may be connected to the intercom signalling buzzer at multiple stations.

Loud-sounding bells may also be provided.

15 STD FACILITIES
A Meter No. 19 can be fitted to the exchange line but if the HES No. 3 is a subsidiary to a PBX equipped with operator recall, a Filter, Frequency, No. 144A must also be fitted in series with the signalling earth in the HES No. 3.

Optional trunk barring by means of Lock No. 29A can be provided at any  station. Permanent trunk barring can be fitted provided that access to the STD network is always available from one station.

16 EXCHANGE SERVICE PROHIBITED OR RESTRICTED
Exchange service may be permanently barred to certain stations if required. Exchange service may also be restricted at certain stations so that either incoming or outgoing calls can only be connected at the discretion of the main station.

17 EXCHANGE LINE MONITORING
Although exchange calls are normally secret, one multiple station may be given the facility of monitoring exchange calls; this facility degrades transmission on the exchange line and its use is restricted to one station only.

18 HEARING AIDS
Handset No. 4 may be provided, when required at multiple and non-multiple stations.

19 EXCHANGE SERVICE WHEN POWER FAILS
The HES No. 3 derives its 50V operating supply from Power Unit 51A which is mains operated; secondary cells are not required. If mains power fails, or is switched off, bothway exchange service is available at all stations but intercom service, lamp signals and the monitoring facility are not. Under these circumstances restricted service stations cannot be given access to the exchange line.

20 OTHER INSTRUCTIONS REFERRING TO HES NO. 3
The following are applicable:-

C3 C3032 - Description
C3 C3033 - Circuit Operation C3 C3034 - Installation

Formerly EI Telephones, Stations , Q1011


TELECOMMUNICATIONS INSTRUCTION
C MARKETING INSTALLATION
3 Internal
C3032
Issue 2, Sept 1973

HOUSE EXCHANGE SYSTEMS NOS. 3 AND 4
Description of Equipment

1 SCOPE OF INSTRUCTION
This Instruction describes the various items of equipment used on the House Exchange Systems (HES) Nos. 3 and 4. The definitions of terms and facilities for the HES No. 3 are described in C3030 and for the HES No. 4 in C3031. Installation of the HES No. 3 is described in C3034 and the HES No. 4 in C3036.

2 CONTENTS Paragraph
TELEPHONE, INTERCOM, NO. 3/1 (HES NO. 3)3
TELEPHONE, INTERCOM, NO. 4/1 (HES NO. 4)4
BLOCK, TERMINAL, NO. 375
BOX, CONNECTION, NO. 6A6
BOX, CONNECTION, NO. 7A7
WALL-MOUNTED RELAY-UNITS8
RELAY-UNIT Q 4059
RELAY-UNIT Q 41010
RELAY-UNIT Q 41511
RELAY-UNIT Q 51612
RELAY-UNIT Q 51913
RELAY-UNIT Q 52414
RELAY-UNITS MOUNTED IN TELEPHONES, INTERCOM15
RELAY-UNIT Q 40816
RELAY-UNIT Q 40917
RELAY-UNIT Q 52718
RELAY-UNIT Q 52819
TWO-WIRE CIRCUIT CONTROL - UNITS AT MAIN STATIONS20
CONTROL-UNIT Q 53521
CONTROL-UNIT Q 53722
NON-MULTIPLE EXTENSION TELEPHONE23
EXTENSION BELLS ETC24
ADDITIONAL RECEIVERS25
LABELS26
INSTRUMENT CORDS AND CONNECTORS27
CABLE28
POWER EQUIPMENT29
RINGING SUPPLY30

3 TELEPHONE, INTERCOM, NO. 3/1
This telephone is used at a HES No. 3 installation which caters for one exchange line and up to five stations. The telephone is basically a Telephone No. 710 and has a cover (Part 6/DCO/627)which is provided with two lenses; it is fitted with a self-locking BELL OFF button in position A, an EXCH button in position B and two split buttons in each of positions C and D.

The moulded base (a standard item) is fitted with a special gravity switch and has been coded Part 4/DBA/107.

Fitted between the gravity-switch pillars in a sub-assembly known as a Switch Composite, No. 1A, which consists of a spring contact unit wired to a Strip, Connection, No. 155B, the assembly having seven flexible spade-ended leads for connection to the telephone circuit. The contact unit is held in position between the gravity-switch pillars by four screws and the connection strip is held at the rear of the pillars by two locating pins and a spring clip.

The plungers and spring contacts located in positions C and D of the latch- plate assembly form the intercom signalling circuits. The spring contacts and plunger in position B are contacts KX of the exchange line circuit, and these may be released either by replacing the handset or by pressing any one of the four buttons in positions C and D. The spring contacts in position A which are adjacent to position B, are contacts KH and these also operate when contacts KX are operated, but they can only be released by replacing the handset; these form the hold circuit of the exchange line. The remaining spring contacts in position A control the magneto bell cut-off or additional facilities. These springs are operated by a special plunger which is fixed to the latch plate by a bracket. The spring assembly is illustrated in Dgm Q 422 and the button arrangement is shown in Dgm Q 424.

Fixed on the sides of the gravity-switch pillars are two Lamp-fittings, No. 16 (incomplete); viewed from the front of the telephone, the fitting on the left-hand side contains a Lamp No. 26H which provides the red lamp signals for the exchange line, whilst in the fitting on the right-hand side is a Lamp No. 26i which provides the engaged signal for the intercom circuit.

The d.c. buzzer for intercom calling is fitted onto the cord grommet frame and the complete assembly has been coded Buzzer No. 2B-2.

The telephone is fitted with a Cord, Inst, No. 20/03AJ, ..., 72 in which is terminated with the multiple cables onto a Block, Terminal, No. 37.

The telephone is normally fitted with a Handset No. 3. The CB telephone has a Dial, Auto, Dummy, No. 6A, The complete circuit of the telephone is shown in Dgm Q 422 and the wiring of the Switch, Composite, No. 1A only in Dgm Q 423. The instrument cord and cable connections for the telephone are shown in Dgm Q 424.

The telephone is available in black, grey and ivory.

.

4 TELEPHONE, INTERCOM, NO. 4/1
This telephone is used at a HES No. 4 installation which caters for one or two exchange lines and up to ten stations (exceptionally eleven stations).

The telephone mechanism is mounted on a metal base and is enclosed by a moulded plastic cover (Part 1/DCO/683).

The telephone when issued is fitted with a Handset No. 3 and a Connector No. 1046A. The overall dimensions of the telephone are approximately 11.25 in (285 mm) x 6.75 in (170 mm) x 4.75 in (120 mm) high.

Above the front sloping face of the cover containing the dial aperture, is an almost horizontal face in which is a rectangular aperture for the press-buttons of the key unit. Over the rectangular aperture and surrounding the press-buttons is a separate escutcheon which is sprung into place and clips onto the metal face of the key unit. This escutcheon contains the station identification labels with their clear plastic covers and the lenses for the exchange line lamps. The labels and plastic covers are removed by pressing at the end of the plastic cover with the blunt end of a pencil or similar object; this causes the middle to bow upwards where the cover and label may be gripped and pulled gently upwards. If the label does not rise with the cover it may be eased up by inserting a pin at the middle by the side of the label and levering gently upwards. The escutcheon is removed by inserting a thin blunt edged blade, or finger tip under the chamfered edge at the back and springing off the rear clip, then lifting upwards to release the front spring clip. In front of the handset rest there is provision for four press-buttons which are used to control the bell cut-off facility and any additional facilities that may be provided.

The telephone cover is fixed by two screws in the handset rest and by a screw in the front of the dial mounting.

The press-buttons are in two rows, from left to right there are the two ivory exchange line buttons engraved 1 or 2, two smaller ivory exchange line release buttons engraved R; ten grey press-buttons for signalling and speaking

to other stations over the intercom circuits, and the single ivory conference button engraved C.

At the front of the base are two bell gongs, over which Relay-units Q 527 and Q 528 (see para 18 and 19) may be mounted as required. The magneto bell is a Bell No. 59A with long flexible leads and has been coded Bell No. 59A-2.

Behind the bell and across the base 'is a printed circuit board with the components of a standard 700-type telephone transmission circuit.

The key unit is in two parts; a metal frame carrying spring-sets for the exchange lines and intercom circuits, and a press-button assembly.

The metal frame screwed to the base of the telephone, carried on each side, the spring assembly of an exchange line and a printed board with spring contacts riveted to it, for intercom signalling and speaking.

At the end of the frame near the exchange line spring contacts is a plunger assembly which operates on second and subsequent overpresses of an exchange press-button. The plunger operates a spring-set to provide operator-recall facility to either exchange line circuits. A second spring assembly inside the frame operates when the station press-buttons are overpressed and provides the intercom signalling condition.

At the end of the frame near the conference button are a number of `polytags' carrying resistors associated with lamp circuits etc.

On the top, near each of the four corners of the frame, is a lug which carries a Lamp-fitting No. 19 and a Lamp No. 41E. The press-button mechanism is held in the frame by a countersunk screw at each corner of the top plate.

On the left-hand side of the base, beneath the dial mounting, is a metal bracket which carries a d.c. buzzer (Buzzer No. 2B-3) for intercom calling.

Behind the key unit frame is a 72-way double-sided terminal block. On the top side is the telephone wiring; both soldered and screwed terminations. The instrument cord, a Connector No. 1046A, and any straps that may be required are terminated on the underside and these terminals are exposed by removing a cover plate from the base.

Over the cord entries at the rear of the base is a metal bracket which carries the intercom transmission feed coil and its associated resistors and capacitor.

The telephone is connected to the multiple cabling via a Box, Connection, No. 6A. The circuit and connector connections of the telephone are shown in Dgm Q 540.

The telephone is available in black, grey and ivory.

The weight of the complete instrument is 81 lb.

5 BLOCK, TERMINAL, NO. 37...
The Block, Terminal, No. 37... is used at HES No. 3 installations to terminate the multiple cables and Telephone, Intercom, No.3/1 at multiple stations. It is also used with a Control-unit Q 535 (see par 21) at a HES No. 4 installation.

The Block Terminal, No. 37... consists of a moulded plastic base (Part 1/DBA/99) on which is mounted a terminal block (Part 1/DBL/91), containing 25 double-sided screw terminations the tablet and base being enclosed by a moulded plastic cover (Part 1/DCO/62.5). At one end of the cover is a cut-out for cord entry and at the other end are three knockouts for cable entry.

The base has been modified to include a hole for back entry of cable and fixing holes for mounting the Block, Terminal, No. 37... over square type conduit outlet boxes, i.e. standard outlet boxes with 2.75 in (70 mm) fixing centres.

6 BOX, CONNECTION, NO. 6A
The Box, Connection, No. 6A has a base area of approximately 6.25 in (160 mm) x 5.75 in (145 mm) and is nearly 2 in (50 mm) high.

Mounted on the metal base is a Connector No. 203B55B,, which is a 55-pin plug. Also fixed to the base on raised pillars are two 28-way terminal blocks (Part 1/DST/861). The inserts of the terminal blocks have screw terminals for multiple cabling on the front side, and solder terminals on the rear side which are wired to the pins of the Connector No. 203B55B. At the side of the connector is a bracket to retain the grommet of the telephone instrument cord (Connector No. 1046A). Also in the base is a hole for back entry of cables.

The grey moulded plastic cover is held on by two fixing screws, and the sides contain knockouts for cable entry and a cut-out for the cord entry. Details of the wiring between the connector and terminal tablets are given in Dgm Q(L) 510.

7 BOX, CONNECTION, NO. 7A
The Box, Connection, No. 7A is identical in size and shape to the Box, Connection, No. 6A. The metal base of the Box, Connection, No. 7A provides mounting on raised pillars for three 28-way double-sided terminal tablets (Part 1/DST/861). These tablets have screw terminals on front and rear sides. There is no provision in the base for back entry of cables. The sides of the moulded plastic cover contain knockouts for cable entry. Typical uses of the Box, Connection No. 7A are shown in Dgm Q 508.

8 WALL-MOUNTED RELAY-UNITS
Two sizes of metal case have been introduced for use with HES No. 3 and No. 4.

Relay-unit Q 405 is contained in a Case No. 131... which has a mounting surface of 12 ins (305 m) x 4.5 ins (110 mm). All other wall-mounted units are contained in Case No. 133... which has a mounting surface of 12 in (305 mm) x 8.75 in (220 m). Both cases extend 7.25 in (185 mm) from the mounting surface.

Circuit components are mounted on a metal plate which is hinged to the baseplate and the wiring form from the components is terminated on a connection strip, which is fixed to the baseplate. Cable entry is via a hole fitted with a grommet in the baseplate.

A clear space of 6 ins (152 mm) must be allowed on the left side of the units when fixing to the mounting surface. This space allows full movement of the hinged plate, with access to the wiring of the relays etc.

A description of each wall-mounted relay-unit is given in para's 9 to 14.

9 RELAY-UNIT Q 405
Relay-unit Q 405 is provided at HES No. 3 installations which have multiple stations only. The unit contains the circuits which control the lamp signals in the Telephone, Intercom, No. 3/1, and the transmission feed relay for the intercom circuit. The wiring of the unit and the multiple cable terminate on a connection strip (Part 1/SST/71) the cable being connected to the screw terminals.

Wiring details are shown in Dgm. Q 405 and in Dgm ID 174, which is pasted inside the cover.

.Cable connections are shown in Dgms Q 403 and Q 404.

When a HES No. 3 is working subsidiary to a switchboard with a low-power ringing source, it may be necessary to provide a local ringing supply, the output of which is controlled by relay contact RG2. Dgm Q 417 shows details of alternative ringing arrangements when working a HES No. 3 subsidiary to a switchboard or when more than 'five bells are to be rung.

The complete unit weighs approximately 51 lb. (2.5 kg).

10 RELAY-UNIT Q 410
Relay-unit Q 410 replaces Relay-unit Q 405 at HES No. 3 installations when a non-multiple extension is required. In addition to the components and circuits of the Relay-unit Q 405, the Relay-unit Q 410 also contains the components and circuits which connect the two-wire line of a non-multiple extension to the multiple wiring of the system.

In this unit there is no spare contact on relay RG, and when a HES No. 3 with a non-multiple extension is worked subsidiary to a switchboard which has a low-power ringing source, it will be necessary to change relay RG. The relay should be changed for a Relay No. 9871, and the additional contact wired as shown in Dgm Q 417, which gives details of alternative ringing arrangements. The relay RG must also be changed and wired to Dgm Q 417, when more than five magneto bells are to be rung at any installation.

The unit wiring and the multiple cable are terminated on a connection strip (Part 1/SST/71), with the cable connected to the screw terminals.

Wiring details of the Relay-unit Q 410 are shown in Dgm Q 410 and in Dgm LD 175, which is pasted inside the cover.

The complete unit weighs approximately 14 lb. (6.3 kg).

11 RELAY-UNIT Q 415
The Relay-unit Q 415 is provided when an inter-switchboard or private circuit is included in a HES No. 3 installation, and is fitted in addition to Relay-unit Q 405 or Q 410.

Relay-unit Q 415 contains a number of circuit elements, which may be strapped according to the type of signalling being used on the circuit.

The wiring details of Relay-unit Q 415 are shown in Dgm. Q 415 and in Dgm ID 180, which is pasted inside the cover.

The connections required when using the Relay-unit Q 415 are shown in Dgms Q 441 to Q 447. Signalling limits for this unit are the same as for a Unit, Auxiliary Apparatus, No. 97 and are given in P1061.

The unit wiring and multiple cables together with the required strappings shown in Dgm Q 441 are terminated on two Strips, Connection, No. 121D mounted back to back; these are all soldered connections.

The complete unit weighs approximately 15 lb. (6.8 kg).

12 RELAY-UNIT Q 516
The Relay-unit Q 516 is fitted to all HES No. 4 installations, and contains the components and circuits which control the lamp signals and exchange line ringing signals at a Telephone, Intercom, No. 4/1 fitted at a multiple station. Relay contacts within the unit are also available, when required, to extend signal and start conditions to the relay-unit of non-multiple extensions or private circuits.

Current through each of the series connected exchange line engaged lamp circuits of a Telephone, Intercom, No. 4/1 is controlled by a transistor circuit. The transistor is mounted on a heat sink which also carries the associated resistors, capacitor and rectifier; this complete assembly has been coded Regulator No. 4A.

The Regulator No. 4A is fixed by two screws to the hinged plate and joined to the circuit by three flexible spade-ended leads. Care must be taken to ensure that these leads are correctly connected otherwise the transistor may be seriously damaged. The regulator is adjusted during manufacture to pass 104mA (- or + 12 ma) under load conditions, and should any component become faulty, the complete regulator must be changed.

Mounted on the baseplate of the relay-unit is a clip to hold a Connector No. 203C55C, which is a 55-way connector that has been provided with a number of straps between certain sockets, and is intended for use at multiple stations where a Telephone, Intercom, No. 4/1 has been disconnected for repair or replacement. By replacing the telephone socket with a Connector No. 203C55C the series circuits of the installation are maintained and service is continued at all other stations. The connections provided in the Connector No. 203C55C are shown in Dgm Q 510.

Wiring details of the Relay-unit Q 516 are shown in Dgm Q 516 and in Dgm LD 192, which is pasted in the cover.

The complete unit weighs approximately 12 lb. (5.4 kg).

13 RELAY-UNIT Q 519
The Relay-unit Q 519 is provided at a HES No. 4 installation to connect the two-wire line of a non-multiple extension to the multiple wiring.

Circuits in the unit provide the non-multiple extension with most of the facilities of a multiple station; these facilities are fully described in C3031.

A Strip, Connection, No. 121M provides the terminating point for the unit wiring, multiple cables and strappings as required. Straps that may be needed should be connected on the permanent wiring side of the Strip, Connection, No. 121M; and the multiple cables terminated on the opposite side.

Details of the wiring are shown in Dgm Q 519 and in Dgm LD 195, which is pasted inside the cover.

When a Relay-unit Q 519 is provided, a Control-unit Q 535 or Q 537 (see para's 21 and 22) is always fitted at the main station and the operation of the Relay-unit Q 519 should be studied in conjunction with the operation of the Control-unit Q 535 or Q 537. Circuit elements and explanatory, notes are shown in diagrams in the Q 5... series.

The complete unit weighs approximately 17 lb. (7.7 kg).

14 RELAY-UNIT Q 524
The Relay-unit Q 524 is provided at a HES No. 4 installation to connect the two wires of a private circuit to the multiple wiring.

The unit contains circuit elements which may be connected by strappings on the Strip, Connection, No. 121M, to terminate the circuit at the HES No. 4 according to the type of signalling to be used. The cable connections and straps required for various signalling groups are shown in Dgms Q 561 to Q 567.

Wiring details of the unit are shown in Dgm Q(L) 524 and in Dgm LD 194, which is pasted inside the cover.

Signalling limits for the Relay-unit Q 524 are the same as for a Unit, Auxiliary Apparatus, No. 97 and these are shown in P1061.

Straps should be connected on the permanent wiring side of the Strip, Connection, No. 121M and cabling should be terminated on the opposite side.

The complete unit weighs approximately 17 lb. (7.7 kg).

15 RELAY-UNITS MOUNTED IN TELEPHONES, INTERCOM
Certain facilities that are available to both HES No. 3 and No. 4 installations are provided by fitting small relay-unit into a Telephone, Intercom, No. 3/1 or No. 4/1 and modifying the instrument cord connections.

These units consist of a Relay No. 16/... or Relay No. 23/6 mounted on a metal mounting plate which is secured over a bell gong.

Other components may also be included, terminated on `polytags' pressed into the metal mounting plate.

The various relay-units for fixing inside Telephones, Intercom, are described in para's 16 to 19.

16 RELAY-UNIT Q 408
The Relay-unit Q 408 is provided in a Telephone, Intercom, No.3/1 when the instrument is to have restricted exchange service.

The unit consists of a Relay No. 16/1 and two diodes (Valves, Electronic, CV 7040) on a mounting plate (Part l/DMO/102), and has spade-ended flexible leads for connection to the telephone circuit.

Dgm Q 408 shows the wiring of the unit and the connections within the telephone.

17 RELAY-UNIT Q 409
The Relay-unit Q 409 is provided in a Telephone, Intercom, No.3/1 when the instrument is to have monitoring facilities.

The unit consists of a Relay No. 1612 wired with spade-ended flexible leads on a mounting plate (Part 2/DMO/102).

Dgm Q 409 shows the wiring of the unit and the connections within the telephone. Relay-Units No. 408 and 409 are mounted over the right-hand side bell gong.

18 RELAY-UNIT Q 527
The Relay-unit Q 527 is fitted in a Telephone, Intercom, No.4/1 when the station is to have restricted exchange service.

When exchanges service restriction applies to only one line the Relay-unit Q 527 should be used and connected to the appropriate line. When both lines are to be restricted the Relay-unit Q 527 should be connected to the line on position one of the telephone and a Relay-unit Q 528 (see par 19) connected to the line on position two.

The Relay-unit Q 527 consists of a Relay No. 16/1 and two rectifiers (Valves, Electronic, CV 8308) on a mounting plate (Part 3/DMO/102), and has flexible spade-ended leads for connection to the telephone. Details of the wiring and telephone connections are given in Dgm Q 527. The Relay-unit is mounted over the left-hand side bell gong.

19 RELAY-UNIT Q 528
The Relay-unit Q 528 is fitted in a Telephone, Intercom, No. 4/1 when both lines are to have restricted exchange service. The unit includes a mounting plate (Part 1/DMO/102) for mounting over the right-hand side bell-gong but in all other respects the Relay-unit Q 528 is identical to the Relay-unit Q 527. Details of the Relay-unit Q 528 are included in Dgm. Q 527.

20 TWO-WIRE CIRCUIT CONTROL-UNITS AT MAIN STATIONS
When a non-multiple extension or private circuit is fitted at a HES No. 4 installation a control-unit must be fitted at the main station. This unit provides the circuit calling and clearing supervisory, and exchange line testing circuits. There are two sizes of control-unit, Control-unit Q 535 which caters for one circuit and is described in par 21, and Control-unit Q 537, which caters for up to four circuits and is described in par 22.

21 CONTROL-UNIT Q 535
The Control-unit Q 535 is a desk unit measuring approximately 3.5 in (90) wide x 5.5in (140 mm) front to back and 2.75 in (70) high; it is fitted adjacent to the Telephone, Intercom, No. 4/1 at the main station.

The unit is contained in a Mounting D 92155 using a cover (Part 1/DCO/672, Grey), and a face plate (Part 1/DPL/2136). The 'EXCHANGE LINE' lenses are Caps, Lamp, No. 79C, Red and the 'EXTENSION' lens is a Cap, Lamp, No. 79C, White. The lamps used are Lamps No. 2-45V. The lamps and lenses are easily replaceable but other components are soldered in and should not normally be changed in subscribers' premises.

The cord associated with the unit is a Cord, Inst, No. 18/04AJ, Grey, 72 ins (1.8m) and this is terminated with the cabling onto a Block, Terminal, No. 37..., both must be ordered separately.

Dgm Q 535 shows the wiring details of the unit and Q 1015 explains the facilities of the unit.

The unit is available in grey only.

22 CONTROL-UNIT Q 537
The Control-unit Q 537 is a desk unit measuring approximately 6.75 in (170 mm) wide x 5.5 in (140 mm) front to back and 3in (75 mm) high; it is fitted adjacent to the Telephone, Intercom, No. 4/1 at the main station.

The unit is contained in a Mounting D,92199 using a cover (Part 1/DCO/676, Grey) and a face plate (Part 2/DPL/2135). In addition to the parts contained in Control-unit Q 535 (see par 21) the Control-unit Q 537 contains four key circuits which are used to connect non-multiple extensions and private circuits for intercom calls. When used at an installation with 2nd choice main station facilities, the Part 2/DPL/2135 is changed (see C3036).

This unit is issued without a cord and Q 3015 describes the conditions governing which cord should be fitted.. When a Cord, Inst, No. 18/04AJ, Grey, 72 ins (1.8 m) is fitted, a Block, Terminal, No. 37... must be used to terminate the instrument cord and cable. When a Connector No. 1046A or No. 1052A is fitted, a Box, Connection, No. 6A must be used to terminate the connector and cable.

Dgm Q(L) 537 shows the wiring details of the unit and C3031 explains the facilities of the unit.

23 NON-MULTIPLE EXTENSION TELEPHONE
A Telephone No. 710 is used to terminate the non-multiple extension. The components to be ordered separately and fitted in the telephone are fully described for the HES No. 3 in Dgm Q 420, and for the HES No. 4 in Dgm Q 550.

24 EXTENSION BELLS ETC
Standard magneto bells, d.c. bells and buzzers are used when extension bells etc are required. Dgm Q 419 shows the connections for HES No. 3 and Dgm Q 545 shows the connections for the HES No. 4.

25 ADDITIONAL RECEIVERS
A Receiver, Watch, No. 8T and a Hook, Receiver, AG are used.

26 LABELS
Particulars of dial labels for Telephones, Intercom, No. 3/1 and No.4/1 are given in C3034 and C3036 respectively, and the labels are described in M0010.

When issued, Telephones, Intercom, No. 4/... are fitted with station identification labels (Labels No. 469/1 and 2 and these are described together with Labels No. 469 in C3036.

27 INSTRUMENTS CORDS AND CONNECTORS
There are two instrument cords and two connectors available for use on HES No. 3 and No. 4 equipment.

Cord, Inst, No. 20/03AJ, 72 ins (1.8 m) is normally fitted to Telephones, Intercom, No. 3/1.

Cord, Inst, No. 25/04AJ, 72 ins (1.8 m) replaces Cord, Inst, No. 20/03AJ, 72 ins (1.8 m) when extra conductors are needed.

Both cords have at one end 41 ins (115 mm) spade-ended conductor tails for Connection to the telephone, and at the other end, have the spade-ended tails formed into two rows of ten. Each row is held in position by strips of flexible plastic, which are moulded over the shanks of the spade terminals. The remaining five conductors of the Cord, Inst, No. 25/04AJ, ..., 72 ins (1.8 m) are left free. The plastic 'harness' assists in quick and accurate connection of the conductors to the Block, Terminal, No. 37...

Each cord is stocked in three colours: black, grey and ivory, and in two lengths: 72 ins (1.8 m) and 120 ins (3.0 m).

The Connector No. 1046A is normally fitted to a Telephone, Intercom,, No. 4/... and may be fitted to a Control-unit Q 537 if required.

The Connector No. 1052A replaces Connector No. 1046A when. extra conductors are needed.

Both connectors have at one end, 41 ins (115 mm) spade-ended conductor tails for connection to the telephone or control-unit. At the other end, soldered to the conductors, is a Connector No. 203C55A, which is a 55-way socket for connection to the Box, Connections, No. 6A.

Both connectors are stocked in three colours, black, grey and ivory, and in two lengths, 72 ins (1.8 m) and 120 ins (3.0 m) Connectors, with 120 ins (3.0 m) cords are coded Connectors No. 1046B and No. 1052B.

28 CABLE
The cable used for HES No. 3 and No. 4 installation is Cable, Distribution ... (12W, 24w or 41w), /0.5 mm. The size and type of cable to be used is given in C3034 for the HES No. 3 and C3036 for the HES No. 4.

29 POWER EQUIPMENT
The HES No. 3 and No. 4 are mains operated installations, and standby batteries are not provided. A Power-unit No. 51A is provided for the HES No. 3 and a Power-unit No. 52A for the HES No. 4.

30 RINGING SUPPLY
The Converter, Ringing, No. 7, which is mounted inside a Power-unit No. 51A or No. 52A is normally provided when a local ringing supply is required for a non-multiple extension or private circuit. Power-unit No. 100A/1 and 100A/2 for use with HES No. 3 and 4 respectively are equipped with Converters Ringing No. 7 and should be provided at installations initially requiring a ringing supply.

Formerly EI Telephones, Stations, Q1016

Introduced around 1963

Click here to download HES 3 diagram (ZIP)

Click here for HES 4 circuit diagrams (PDF)

 

 
 
BACK Home page BT/GPO Telephones Search the Site Glossary of Telecom Terminology Quick Find All Telephone Systems

Last revised: December 19, 2010

FM