KEY AND LAMP UNIT No's 2 & 10


TELECOMMUNICATIONS INSTRUCTION
C MARKETING INSTALLATION
3 Internal
M2001
Issue 1, Apr 82

KEY AND LAMP UNITS No's 2A AND 10A
DESCRIPTION

GENERAL
The Key and Lamp Units Nos. 2A and 10A are both designed to meet two primary applications, order table working and speech broadcasting, which can be made locally. With wiring modifications they may also be used to provide Key and Lamp Units for a limited range of non-standard applications. This Instruction describes the units and associated apparatus for use in the two primary applications.

PHYSICAL DESCRIPTION
Key and Lamp Unit No. 2A
The keys and lamps are in the same plane to allow the key-panel to be console-mounted if required. The unit has ten lamps, ten 1000-type keys and a non-locking microswitch. It is wired for ten basic line circuits but additional springs on the tenth key are wired to the connection strip to enable it to be used for purposes other than as a line key if necessary. The wiring-form from the keys to the connection strip includes three spare wires for use in modifications. In the units as issued the keys are wired for speech broadcast applications and this permits coupling between lines which is not normally permitted for exchange line or PBX extension line terminations. The modification to the key wiring to prevent the customer connecting lines together is shown on Diagram SA9157 Sheet 1.

The unit is two-tone grey with an acrylonitrile-butadiene-styrene copolymer (ABS) cover, which can be removed by loosening two screws at the rear. The key panel is supported by two pivoted brackets, giving easy access to the wiring and components.

Key and Lamp Unit No. 10A
The flange on which the micro- switch is mounted makes the unit unsuitable for console mounting. This unit has two sets each of ten lamps and ten 1000-type keys and a single micro switch. Each set of ten lamps and ten keys is wired identically to the Key and Lamp Unit No. 2A, there being two sets of connection strips to which the two sets of lamps and keys are independently wired.

This item is also two-tone grey. The ABS cover can be removed by loosening two screws at the rear. The key-panel is supported by two pivot brackets giving easy access to the wiring and components.

ASSOCIATED EQUIPMENT
Jack Unit No. 1B
The operator's circuit associated with the key and lamp unit is housed in this unit, which is normally fitted to the underside of a desk. The unit includes the speech-circuit elements of a 700-type telephone on a printed wiring board, a Jack No. 84A and a French-grey ABS cover. A Headset No. 1 or a Handset No. 3 is plugged in to complete the circuit. Jack Unit No. 1B supersedes Jack Unit No. 1A.

Regulator No. 6B
To eliminate transmitter noise when short exchange or PBX extension lines are connected to the installation it may be necessary to use a Regulator 6B in conjunction with Headsets Nos. 1 & 2. The Regulator No. 6B has been designed to be associated with a Jack Unit No. 1B. Should a Regulator No. 6B be required with a Jack Unit No. 1A it must be fitted using a Block Terminal 36.

Unit, Auxiliary Apparatus, SA 9151
This unit accommodates five, line terminations for exchange lines or PBX extensions. It also includes a flashing circuit consisting of a group of relays providing ten outlets of interrupted earth-pulses to flash the calling lamps. There is space for addition of a second distribution relay if more than ten outlets are required. A mains-fail relay for a 6V a.c. supply can also be fitted for use if required.

The equipment is accommodated on a 19 in x 5.25 in mounting-plate suitable for rack mounting. A cover is included.

Unit, Auxiliary Apparatus, SA 9152
This unit accommodates five line circuits identical with those in the Unit, Auxiliary Apparatus, SA 9151 but has no flashing circuit. The mounting-plate is 19 in x 3.5 in and it is suitable for rack mounting. A cover is included.

Unit, Auxiliary Apparatus, SA 9153
This unit accommodates the line terminations for five private circuits on a 19 in x 3.5 in mounting-plate suitable for rack mounting. A cover is included.

The normal signalling arrangements are:-

  • Generator/earth-loop in, generator/a.c. out or,
  • Generator/d.c. bothway. The unit is primarily intended for speech-broadcast working.
  • In cases of complaints of poor transmission on any circuit terminated on a UAA SA 9153 modify the UAA in accordance with Works Specification S(W) 2090.
  • Unit, Auxiliary Apparatus, SA 9219 This unit provides lamp flashing equipment only, there is provision for five additional 3000 type relays, i.e. Mains-fail, Night Alarm or additional flashing relays. There is provision for mounting a bridge rectifier in addition to the relays for use with the Mains-Fail relay.

STRIP MOUNTED SET 1A1/SA 9207
This unit comprises two control relay-sets for the combined use of PO headsets on customers approved radio circuits and PO lines with access for recording speech. The mounting plate dimensions are 19 in x 5 in and it is suitable for rack mounting. A cover is included.

ORDER TABLE WORKING

General
In certain organisations much of the incoming telephone traffic is often of a type requiring information be be quickly supplied in response to inquiries. A system where a group of operators is specially detailed to deal with such traffic is known as order table working; railway inquiry bureaux as an example. The essence of such an installation is speed in answering and to this end a group of lines, usually exchange lines or PBX extensions, is multiplied over a number of key and lamp units. An incoming call on one line is indicated by a lamp signal for that line at each unit and is answered by the first free operator. Operating the answering key causes the appropriate lamp to glow at all positions as a visual-engaged signal (VES). Similarly, when any line is taken into use to originate a call a VES is given to all operators. A holding facility is provided on each line to enable an operator to hold one line while speaking on another, the VES will continue during hold conditions. Intercommunications between lines is prohibited by rearranging the wiring to each answering key when the equipment is first installed.

Order table working with Key and Lamp Units Nos. 2A and 10A.
Method of Use

A single lamp per line on each Key and Lamp Unit is used to provide both calling and visual-engaged signals. An incoming call causes the lamps to flash on every unit to which it is connected. There is an audible alarm which is common to all circuits, a switch is provided so that the audible alarm can be cut off when required. An alarm on a single circuit maybe provided in accordance with Diagram SA 9157 Sheet 9. The visual engaged condition is indicated by a steady glow. When not in use all keys are in the up (Receive Call) Position. To answer a call a free operator moves the appropriate key to the down (Speak) position, the appropriate lamp glowing at each of the multiplied units indicates to all other operators that the call has been accepted. Should the answering operator wish to hold the call the key is moved to the mid (Hold) position. At the end of the call the key is restored to the up position and the multipled lamps darken. If the lines are PBX extensions a microswitch operated by the press button can be wired to provide recall and enquiry facilities.

Equipment
In standard order table installations the first five lines are terminated on a Unit, Auxiliary Apparatus, SA 9151, which also provides the lamp-flashing equipment. Additional lines are terminated on Units, Auxiliary Apparatus, SA 9152 (one unit for every five extra circuits). For up to ten lines each operator has on Key and Lamp Unit No. 2A, a jack unit with headset or handset and usually a drawer-mounted dial; other dial-mountings are permissible to meet local requirements, or a telephone can be used as the operating instrument if the subscriber prefers. For 11-20 line installations each operator requires a Key and Lamp Unit No. 10A. Installations of more than 20 lines can be arranged but must be specially assessed by the GM.

Power Supplies
The 50 V dc supply is provided by a Power Unit No. 52A and its output is sufficient for an installations of up to 20 lines, i.e., an installation containing one Unit Auxiliary Apparatus, SA 9151 and up to three Units Auxiliary Apparatus, SA 9152. The 6v ac supply is provided by either a Transformer No.261A for 3 up to 150 lamp appearances or a Transformer No. 315A which will cater for up to 400 lamp appearances.

Transformer mounting
The Transformer No. 261A should be mounted inside the Power Unit No. 52A by using two straps made locally. Later issues of the power unit will have holes drilled in positions suitable for securing the transformer direct to the base plate. The primary (Mains) winding of the transformer should be connected in parallel with the primary winding of the power unit mains transformer so that the mains fuse protects both transformers. The 6v a.c. output circuit should be protected by using a fuse No. 36A/7 fitted in either the FS3 or FS4 position (depending on permanent wiring) and removing the strap between FS3 and FS4 (see Dgm N 637). The transformer No. 315A is unshrouded and is too large for mounting inside the power unit. A protective cover having adequate ventilation should be constructed locally to guard the transformer from accidental contact. The cover should also enclose the associated fuses and terminal blocks and be effectively earthed. The primary (Mains) circuit of the transformer should include a Fuse No. 36A/2 and a Block Terminal No. 21/3 for connecting the mains lead. A Fuse No. 57A/... of adequate rating for the installation and a Block Terminal No. 21/2 for connecting the 6v a.c. output conductors should be included in the secondary circuit.

SPEECH BROADCASTING
General

In speech broadcasting systems a spoken message is transmitted by a controlling operator over a number of lines simultaneously. The lines are frequently private circuits, but exchange lines may also be so connected. Under broadcast conditions an out-station can signal back to the operator, who has to suspend the broadcast and move the appropriate line key from the 'Broadcast' to the 'Speak Single' position to deal with the caller individually. With the extension of STD, exchange line broadcasting tends to diminish because of timed local calls but may still be retained as an emergency facility or to give service to subscribers awaiting the installation of private circuits. Where a single operator broadcasts to a large number of lines a broadcast amplifier is necessary to compensate for the teeing losses in the office. It does not raise the level of speech transmitted to line nor does it compensate for line loss. The principle users of speech broadcasting systems are subscribers whose primary requirement is the rapid dissemination of up to the minute information.

Speech broadcasting using Key and Lamp Units Nos. 2A and 10A.

Method of use
When used as a speech broadcast switchboard a single Key and Lamp Unit No. 2A can only accommodate nine lines, the tenth key being used as the 'Operator Broadcast' key. If several units are coupled together under the control of one operator, however, only one of the units is restricted to nine lines. Similarly a Key and Lamp Unit No. 10A will accommodate nineteen lines, the last being used as the 'Operator Broadcast' key. 'When not in use all the keys are in the mid-position (Receive Call). To answer a single call the appropriate line key is moved to the up position (Speak Single). However a private circuit broadcast is usually originated by the operator. The line keys of the circuits to be included in the broadcast are moved from the normal mid-position to the up position (Speak Single) and the common ring key (microswitch) pressed to apply ringing. When all stations are ready to receive the broadcast the line keys are moved to the down position (Speak Broadcast) and the 'Operator Broadcast' key is moved down to complete the broadcast circuit.

Should an outstation wish to call the operator during the broadcast, the call button is pressed causing the lamp on his particular line to glow. To deal with the call the operator must restore the 'Operator Broadcast' key and move the line key of the calling circuit to the 'Speak Single' position. On exchange line broadcasts the outstation usually originates the call, which causes the line lamp to glow. The operator answers in,the 'Speak Single' position and connects the line to the broadcast by moving the key to the 'Speak Broadcast' position. The recall facility is not provided on exchange lines. To hold condition is either from the Operator's circuit or from the broadcast matching transformer; there is no 'Hold' position for the keys.

Various speech broadcasting arrangements using K & LU's 2A are provided for Exchange Telegraph Co. These are listed in TI EL C4195.

Equipment
Private circuits are terminated on Units, Auxiliary Apparatus, SA 9153 and exchange lines on Units, Auxiliary Apparatus, SA 9152, each unit taking five circuits. The number of key and lamp units will depend on local requirements. The operator's circuit is equipped with a jack unit, a headset or handset, and on exchange lines, a suitably mounted Dial. Miscellaneous equipment for the operator's circuit includes a matching transformer appropriate to the type of line and battery-feeding arrangements or one more Units Amplifying No. 23D.

Power supplies
The 24v d.c. supply is derived from a mains operated Power-Unit No. 57A, but where a suitable supply already exists this may be used. A separate 6v a.c. supply is not required as the lamps are fed, each in series with a resistor contained within the key and lamp unit, from the 24V d.c. supply. Current consumption is small since, under broadcast conditions, only the operator's instrument is energised, the rest of the equipment being quiescent.

NON-STANDARD APPLICATIONS
Apart from the two main uses described the key and lamp units are designed so that with the minimum of modification they can be adapted to provide non-standard requirements for which a key and lamp unit is necessary. If extensive modification is required consideration should be given to the use of Case No. 174A Key and Lamp Unit No. 12A (A Key and Lamp Unit No. 2A minus keys and wiring) or Mountings D 92135 and D 92199 as alternatives. Dgm SA 9157 has been introduced to satisfy a number of requests to terminate private circuits on order table installations. The modifications necessary to effect exchange prohibition are shown, and also the various locally constructed relay-sets required for different methods of signalling when this cannot be achieved with Unit Auxiliary Apparatus SA 9153. A circuit to give inter-communication between operators on two separate groups of order tables has been included and the facility to provide a separate audible alarm for one circuit in a group or for a single circuit on one key and lamp unit in a group is also shown.

CONSOLE-MOUNTING OF KEY-PANELS
To meet demands for console mounted key- panels the Key and Lamp Unit No. 2A, Incomplete, is available. (See Drg 91613). It comprises a key-panel with its wiring-form and connection strips. The method of fitting should be devised locally, depending on the console provided by the subscriber. The key-panel of Key and Lamp Unit No. 10A is not suitable for console mounting.

STANDBY BATTERIES
Where the subscriber requires the installation to function during interruption of the mains supply, the request should be dealt with locally and be the subject of special assessment by the GM. It is pointed out that on order table installations a separate battery supply will be necessary to provide power for the lamps, which need a far larger current than the rest of the equipment. Since a suitable 6V rectifier is not provided by the PO it is suggested that a Rectifier No. 105A be used and the lamps changed to Lamps No. 2 12V-20. For larger installations a rectifier with a greater output should be obtained locally.

METHOD OF CHANGING LAMPS
Key and Lamp Unit No. 2A Remove the lamp cover by sliding the retaining clips at each end towards the centre and lifting the cover. The lamp jack strip which is then exposed may be drawn forward by unscrewing the fixing screws at each end enabling a lamp to be gripped for removal and replacement.

Key and Lamp Unit No. 10A Remove the individual plastic lamp cover by pulling it away from the key-panel to expose the lamp. Remove the lamp with an Extractor No. 5.

DIAGRAMS
The following diagrams are available:-

SA/SAW 9151 - Unit, Auxiliary Apparatus SA 9151. Five exchange line terminations and lamp flashing equipment
SA/SAW 9152 - Unit, Auxiliary Apparatus, SA 9152. Five exchange line terminations
SA/SAW 9153 - Unit, Auxiliary Apparatus, SA 9153. Five private circuit terminations
SA/SAW 9154 - Key and Lamp Units Nos. 2A and 10A
SA/SAW 9155 - Jack-unit No. 1A
SA 9156 - Order table working using Key and Lamp Units No. 2A and 10A. Up to 20 exchange lines or PBX extensions
SA 9157 - Order table working using Key and Lamp Units No. 2A and 10A. Special applications
SA 9160 - Speech broadcast working using Key and Lamp Unit No. 2A. Up to nine exchange lines or PBX extensions
SA 9161 - Speech broadcast working using Key and Lamp Unit No. 2A. Up to nine private circuits
SA 9162 - Speech broadcast working using Key and Lamp Unit No. 2A. Up to nine private circuits with amplifier
SA 9163 - Speech broadcast working using Key and Lamp Units No. 2A and 10A. Over nine exchange lines or private circuits
SA/SAW 9207 - Strip mounted set 1A1/SA 9207. Control relay set for order table equipment having common use of PO headset on PO lines and subscribers radio equipment.


TELECOM INSTRUCTION
C MARKETING INSTALLATION
3 Internal
M2002

KEY AND LAMP UNITS NO. 2B AND 10B

INTRODUCTION
The Key and Lamp Units Nos. 2B and 10B are connectorised versions of the Key and Lamp Units No. 2A and 10A respectively. All existing features of the Key and Lamp Units No. 2A and 10A are retained. Key and Lamp Units Nos. 2B and 10B include Connectors No. 226 mounted within the rear of the units to effect a speedier installation.

Connectors No. 226 are terminated using "Insulation Displacement Termination Technique" (IDT).

DESCRIPTION
The unit is two-tone grey with Acrylonitrile-Butadiene-Styrene copolymers (ABS) cover, which can be removed by loosening two screws at the rear. The key panel is supported by two pivoted brackets giving easy access to the wiring and components. The connector No. 226 is mounted by two special screws (4/DSC/575) on a "H" shaped bracket. This bracket is secured to the base by four screws. The unit has ten 1000 type keys, ten lamps and a non-locking microswitch all which are mounted in the front plate of the unit. It is wired for ten basic line circuits and the tenth key has additional springs which are wired to the connection strip to enable it to be used for purposes other than a line key if necessary. The wiring-form from the keys to the connection strips mounted on the base contains three spare wires which can be used for modifications. The wiring-form from the 226 connector is terminated to the connection strips by either wire-wrapping or soldering. This cable form also includes four spare wires which can be used for additional circuits. The units are issued with the keys wired for speech broadcast applications and this permits coupling between lines, which is not normally permitted for exchange line or PBX extension line terminations.

The modification to the key wiring to prevent the customer connecting lines together is shown on Diagram SA 9157 Sheet 1.

This is only part of the TI.

Introduced in 1964.

Click here the the circuit diagrams (PDF)

 
 
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Last revised: November 28, 2010

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