A.T.E. PROTEA

The ATE Protea telephone owed a lot to the Ericsson Etelux and could be used either as a table or as a wall telephone. It was fitted with ATE's 'dimple' dial, in which recesses replaced the normal finger holes on the dial, and a plug-and-socket line connection.

It was fitted with a Electromagnetic microphone.

Introduced in 1968.

Colours: Black, ivory, two-tone grey, red, yellow, green.

Users:      South African Post Office.
 

An article from the South African Institute of Electrical Engineers
January 1968

South Africa produces a radically new telephone
The Protea

The South African Post Office introduced during December an entirely new telephone, known as the Protea. Both in circuitry and appearance it represents a radical departure. It is undoubtedly the most advanced telephone in the world today, and the first to be brought into general use by any administration in which the carbon microphone is replaced by an electromagnetic microphone.

The basic principles of the telephone were formulated by the Post Office laboratory, where a strong team of engineers and technicians developed the original circuits and, in close collaboration with the manufacturer, produced a prototype instrument for field trials. After careful study of the results the final instrument was made.

The Protea telephone is made only in South Africa and its advantages may be summarized as follows:-

1. Maintenance costs will be lower, mainly because the carbon transmitter and the boll have been replaced by electronic devices.

2. The transmitter noise level and distortion have been greatly reduced.

3. The line regulation has been improved to such an extent that the sending level on a long line (1000 ohm loop resistance) is actually slightly higher than for a line of zero length. The stability of the sending level is also greatly improved.

4. The impedance of the telephone facing the line has been improved, thus reducing return losses - a matter of cardinal importance in the national transmission plan.

5. The bell has been replaced by a tone-caller.

6. The telephone can easily be adapted for use with an electronic exchange and push-button dialling.

7. It is much smaller than the standard telephone and has a neat and modern appearance. The case and handset are made of exceptionally tough plastic in an attractive range of colours.

Tone calling was not introduced as a novelty. The electrical-to-acoustic power conversion efficiency is higher than for a magneto bell and its carrying power is greater. Since the necessary components for tone signalling were already present in the amplifier, their use in an oscillatory circuit represents a further economy by eliminating the bell coils and gongs. Another saving arises from the use of the microphone as the tone transducer to signal incoming calls. Tone calling also influenced the shape of the case, which acts as an acoustic resonator to increase the sound output from the transducer. The output is sufficiently high to justify the provision of a rear-mounted switch which may be set to soft, medium or loud.

Other innovations include a vulcanized rubber mat on the base which holds the telephone firmly in position in spite of its smallness, a coiled handset cord and facilities for a built-in dialling lock.

The Protea telephone, a completely South African advance, is available in ivory, red, black, green, two-tone grey and two-tone brown
 

Demonstration array of the various colours of the Protea telephone, introduced in South Africa during 1968

Last revised: April 11, 2022