Receiver Telesonic – Dated 1944 ‘SOE/Resistance’

Original WWII Receiver Telesonic in good condition. The Receiver Telesonic was used to maintain one way verbal contact from a central command post to dispersed Royal Engineers working parties such as bridge construction and similar operations. The noise of battle or just the necessity for absolute silence, coupled to a small range, without the use of wireless which could be picked
up, led to the development of this system which was based on audio frequency induction. Amplified speech from an amplifier (known as ‘Transmitter Telesonic’) was radiated by a loop of cable of maximum 120 yards in diameter. The signal was picked up by a receiver (‘Receiver Telesonic’) which had a four stage amplifier and a special pick-up coil which was wound on the outside of the receiver case. Six receivers were issued with each transmitter. Reported is the issue of Telesonic receivers to resistance groups in Europe for inductive overhearing (sometimes referred to as ‘tapping’) of telephone lines. The Telesonic receiver was a self contained unit housed in a small metal box, normally carried slung from the shoulder by a carrying strap, or made fast to the belt by the two webbing straps fitted at the back of the case. This example is in good condition, dated 1944, and comes complete with instructions, which have come loose from the lid.

DATA SUMMARY
Organisation: SOE
Design/Manufacturer: M.E.C.
Year of Introduction: First examples were dated 1944
Purpose: Overhearing of telephone conversation without
physical contact to a line.
Range: Up to 200 Yards (In its original function!)
Circuit Features: Four stage AF amplifier. Pick-up coil
wound on the outside of the case. High impedance
headphones C.H.R. Double Mk. VI.
Valves: Hivac XH1.5V (3x); Hivac XP 1,5V.
Power Supply: LT: Battery, dry, lamp, electric 3V; HT:
Battery dry HT 45V No. 4.
Size (cm): Height 15, length 18, width 6.
Weight: 2.3kg including batteries