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TEL/2K, TEL/10K, TEL/12K & TEL/42K

The GEC 706 Tropical Telephone

The Gecophone, first produced in 1929, was an outstanding instrument, which has given efficient and reliable service to subscribers throughout the world for over 30 years. The G.E.C. 706 Telephone (the New Gecophone), while maintaining the same high standard of reliability, has been re-designed to meet the requirements of the modern age. New materials and components are combined to give a high-performance telephone which is available in a wide range of colours, selected to harmonise with modern furnishings and decorative schemes.

The same basic instrument can be used either as a table or wall-type telephone, thus simplifying the problem of stocking spare parts.

The overall performance of the new instrument is higher than that of the former Gecophone, so that longer lines or smaller conductors can be used, whilst maintaining the same high standard of service. The efficiency of the 'G.E.C. 706' Telephone is such that on short lines the volume of received speech may, in some cases, be considered as uncomfortable to the ear. To  remedy this, an automatic volume regulator is fitted, to maintain the speech at a comfortable level.

The G.E.C. 706 telephone is pleasing to see and comfortable to use. The seven colour arrangements ensure that there is at least one choice to harmonise with any surroundings. A plate is fitted across the cradle below the handset to allow easy lifting and carrying of the instrument by one hand.

All components, including the dial, are mounted on the base plate and are easily accessible for maintenance by the loosening of two screws in the cradle, which allows the case to be easily removed without inverting the telephone. The number ring fits to the case round the outside of the dial and is completely independent of the dial. This greatly improves the ease with which the characters can be read, even under indifferent lighting conditions. The arrangement and type of characters can be varied to suit special requirements.

The G.E.C. 706 telephone is readily converted from table to wall mounting, the fundamental changes being the turning of the dial and number ring, and the replacement of the lifting handle by a special clip to hold the handset when the telephone is in a vertical position.

The handset has been designed to give not only the greatest comfort to the user, but also maximum efficiency from the transmitter. The shape ensures that when the receiver is held to the ear in the normal manner, the transmitter is naturally located in the most effective position. Compared to previous instruments, the handset is very light in weight and access to the receiver and transmitter inset capsules is gained simply by unscrewing the earpiece and mouthpiece.

The transmitter is of the carbon-granule type. Its good frequency response and power output have been well proven in the past and have contributed notably to the high performance of the original Gecophone.

The receiver is of the new rocking armature capsule type and has a very high electro-acoustic conversion ratio. Acoustic equalisation produces an improved frequency response. The light alloy diaphragm increases the ratio of effective area to effective mass. The magnet is stabilised during manufacture, so that it has optimum strength.

The whole improvement gained by use of this receiver is not needed on the receiving side. In consequence a new induction coil has been designed to transfer some of the improvement to the sending side.

In effecting the transfer of gain from receiving to sending side, the highest practicable degree of sidetone suppression has been maintained. The circuit is designed to give maximum suppression of sidetone on reactive lines (i.e., cable pairs), since the vast majority of telephones are connected to their exchanges by multi-pair cable.

The G.E.C. 706 telephone for use with automatic exchanges is fitted with a new dial, which, whilst retaining the well-known and reliable action of the G.E.C. Trigger Dial, has been modernised to conform to the styling of the remainder of the telephone. The finger plate is made of plastic and is in the same colour as the case of the instrument. The standard dial operates at 10 impulses per second and has a break-to-make ratio of 2:1. Dials having other ratios can be fitted if required.

A light plastic cover fitted to the back of the dial, giving complete enclosure of the mechanism, is a standard arrangement for protection against dust.

The connexions for the dial are in the form of a cord included in the cable form for the telephone. Conversion from an automatic to a manual telephone merely necessitates the replacement of the dial and the number ring by a dial dummy.

The ringer is also of a new design. It includes a new lightweight ceramic magnet and the coil has a resistance of 1,000 ohms with an impedance of 17,000 ohms at 1000 c/s. It responds to alternating ringing current from hand or automatic ringing machines. Coils of higher impedance for multi-party working are fitted when required.

The cradle switch has been designed to eliminate any likelihood of sticking plungers. A new type of springset is fitted which still retains the twin contact effect, but gives more control over the adjustment and tensioning of the springs. A transparent plastic cover is fitted over the springs to prevent dust accumulating on the contacts.

Owing to the high efficiency of the G.E.C. 706 telephone, some subscribers on short lines might be embarrassed by excessive volume. This is overcome by the fitting of a fully automatic jacked-in volume regulator which limits sensitivity on short lines but restores full efficiency on long lines.

The telephone can be supplied without regulator if required.

The G.E.C. 706 telephone is designed and fully tested for service in all climatic conditions experienced in countries throughout the world. Special insulation is included, as well as adequate ventilation and protection against humidity.

The handset is connected to the instrument by a special P.V.C. covered coiled cord, supplied in colour to match the handset. The rosette cord is also covered in P.V.C.

A Magneto Extension Bell in the G.E.C. Catalogue No. BE1100 or BE1200 series, can be supplied when specified to provide calling signals at a distant point or augment calling signals in very noisy surroundings.

As a result of these performance improvements, the telephone will operate over a local line loop of 1120 ohms of 6.5lb cable (0.5mm conductor) with a performance equal to that of previous telephones operating over a local line loop of 660 ohms; i.e., a local line may be extended by 70%. Alternatively, it will operate over a length of 4 lb cable (0.4 mm) with a performance equal to that of a previous telephone operating over the same length of 10 lb (0.6 mm) cable.

In comparison with its predecessor, the G.E.C. 706 telephone shows an improvement in performance of 4 to 6db on receiving and 6db on sending.

The G.E.C. 706 telephone can be supplied in the following colours:-

  • Two-tone grey
  • Two-tone green
  • Concord Blue
  • Topaz Yellow
  • Lacquer Red
  • Black
  • Light Ivory

All mouldings are in a modern plastic material, acrylonitrile butadeine styrene (ABS), are colour fast (thus ensuring good colour matching when replacing parts) and also high impact strength.

Unless otherwise specified, number rings are numbered:- 0, 9 . . . . . . . . .  1 Clockwise.


Type Catalogue Number
G.E.C. 706 Telephone, automatic, table model TEL/2K/ATT
G.E.C. 706 Telephone, C.B., table model TEL/2K/CTT
G.E.C. 706 Telephone, automatic, wall model TEL/2K/AWT
G.E.C. 706 Telephone, C.B., wall model TEL/2K/CWT
G.E.C. 706 Telephone, automatic, table model, with recall facility TEL/42K/ATT
G.E.C. 706 Telephone, automatic, wall model, with recall facility TEL/42K/AWT

A ship's version of this telephone is also available.

Taken from the GEC leaflet STL 16C

GEC Telecommunications article

For conversion to the UK plug and socket system, please see GPO Telephone No. 706

Circuit Diagram

Circuit Diagram - more of less the same as the GPO 706

Paster found in some telephones
The resistor is can be found in the diagram above

The New Gecophone

The text is as above, but the phone is called the New Gecophone.

This is the first issue of the publicity pamphlet and shows a grebe handset cord.  Later pamphlets showed a coiled handset cord.

Type Catalogue Number
New Gecophone, automatic, table model TEL/10K/ATT
New Gecophone, C.B., table model TEL/10K/CTT
New Gecophone, automatic, wall model TEL/10K/AWT
New Gecophone, C.B., wall model TEL/10K/CWT
New Gecophone, automatic, table model, for shared service TEL/14K/ATT
New Gecophone, C.B., table model, for shared service TEL/14K/CTT
New Gecophone, automatic, wall model, for shared service TEL/14K/AWT
New Gecophone, C.B., wall model, for shared service TEL/14K/CWT
New Gecophone, automatic, table model, with recall facility TEL/12K/ATT
New Gecophone, automatic, wall model, with recall facility TEL/12K/AWT

Taken from the GEC leaflet STL 16A

Additional Pictures

This model is tropicalised - so it has a vent above the dial and mesh covering the bell sound slots in the base




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Last revised: October 11, 2022