Subscriber’s amplifying set
This set is composed of a two-way amplifier and a telephone instrument, both fitted in one cover. The exterior of the set is similar that of the standard Ericsson telephone of bakelite. It is designed for use by persons with poor hearing and also for use with lines having low transmission properties. For this latter reason amplification of outgoing speech has also been provided for. The maximum amplification of incoming speech is about 2.3 neper (20 db) and this amplification can be regulated by means of a potentiometer, the knob of which is placed in the bottom right hand corner of the set. The input level should not, however, exceed about 1.s neper (11.5 db), to avoid distortion. For outgoing speech the amplification is usually adjusted so that zero level is obtained at the near end of the line. For lines giving poor transmission the output can be adjusted to a certain positive level by altering the tappings of a transformer. In this manner the amplification can be regulated 0.8 neper (7 db) in steps of 0.2 neper (1.75 db). The highest possible output level will consequently be + 0.8 neper (7 db).
The set requires 1 battery RK 210 of
1.5 V and 1 battery of 60 V; these two batteries are contained in a battery case RK 2312 supplied on request with the set. The valves are of the Marconi type L 11.
The amplifier is switched on and off by the lifting and replacing of the microtelephone.
dial blank RG 5000 covering the hole for the dial, microtelephone RE 1060 of black bakelite with removable capsule transmitter RC 4000/40, 40 ohm, and cord RS 6162, cover of black-enamelled sheet iron, knob for adjustment of the amplification, bell box, instrument cord RS 9702, two Marconi valves L 11.
height 140 mm, width 233 mm, depth 175 mm, weight 3.4 kg inc. bell box.
Taken from the L. M. Ericsson Telephones and Signalling Material Catalogue No. 188 (1934)
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