PYE/TMC TELEPHONE No. T103 (1760) and T104 (1761)

Magneto Desk Telephones Types 1760 & 1761

Catalogue Nos. T103 (Type 1760) and T104 (Type 1761)

The PyeTMC magneto telephones are a development of the 1746 automatic telephone instrument currently in use throughout the world. They retain the attractive and modern design features of the 1746 and also provide the latest highly efficient receive and send characteristics.

Calling in the 1760 and 1761 magneto telephones is provided by a solid state ringing current generator which is powered from dry cells. The telephone and generator are an integral unit. Operation of the ringing generator is by means of a pushbutton which replaces the more usual crank handle associated with earlier models. The generator fitted in the type 1760 has sufficient power to ring up to four bells in series or two bells in parallel at the end of a 1000ci line, whereas the type 1761 is equipped with a more powerful version capable of ringing up to ten bells in series or four bells in parallel also at the end of a 1000c line.

Both telephones are supplied with line cords wired to terminal blocks. The 1760 telephone has a four conductor line cord and the 1761 telephone a six conductor cord -enabling an extra extension to be easily connected.

The design incorporates printed wiring boards and the use of modern miniature components which provide utmost mechanical and electrical reliability. Ease of servicing is ensured by the simple internal layout. Whilst fully compatible with existing magneto systems, this telephone has the additional advantage that it can be converted into a central battery or automatic telephone if required.- Also a direct line connection between two telephones may be arranged.

Built to a high standard of finish the telephones are suitable for use in all environmental conditions. All components exceed the
requirements of British Standard Specification B5201 1 category 10/055/21.

Dimensions/Weight (unpacked)
Height-over handset - 127mm
Width-over handset - 237mm
Depth - 216mm
Type 1760 - 1.5kg
Type 1761 - 1.85kg

Technical Data

Case and handset moulded in copolymer of acrylonitrile butadiene and styrene (ABS) available in two-tone grey, grey, black or ivory. In the 'two-tone grey version the dummy dial, handset and cords are of the darker tone.

PVC-covered cadmium-copper tinsel conductor cords. Held in position by grommets which relieve conductors of any stress.
Line cord, straight - 3000mm
Handset cord, coiled - 250mm
Uncoiled - 1700mm

Cradle switches
Sealed microswitches.

Ringing generator
Type 1760
Silicon transistor ringing generator powered by 4.5V d.c. will ring four 1000 ohm bells in series via one 1.8uF capacitor at the end of a 1000 ohm line or two 1000 ohm bells via two 1.8uF capacitors in parallel at the end of a 1000 ohm line.

Type 1761
When powered by 4.5V d.c. the generator will ring ten 1000 ohm bells in series via one 1.8uF capacitor at the end of a 1000 ohm line, or at 6.0V d.c. four 1000 ohm bells via four 1.8uF capacitors in parallel at the end of a 1000 ohm line.

Carbon granule replaceable capsule type. The change in sensitivity over the input range 3-30 dynes per sq. cm. is less than 5dB at a given frequency in the range 300-3400Hz.

Rocking armature, replaceable capsule type. The receiver has a mean sensitivity of +46 2dB relative to 1 dyne per sq. cm. per VmW of available power when tested with an artificial ear.

Double coil, resistance 1000 ohm, impedance ranging to 20k ohms at 1000Hz. Ringing current frequency range 15 to 30Hz.

Power Supply
An external power supply of 4.5V d.c. or 6.0V d.c. is required connected at the terminal block.

Conversion to C.B. and auto working
The appropriate parts for these conversions, together with the necessary circuits and fitting instructions, can be supplied.

Wall conversion A wall-mounting can be supplied Cat. No. A481.

Suitable for use conditions.

Taken from Publicity Leaflet A.A.7.74 (dated 1974)

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Last revised: February 04, 2019