This is a general-purpose, portable, up-to-date (for 1940) super-heterodyne receiver of die-cast light alloy and sheet aluminum elaborately designed. It operates on an intermediate frequency of ____ and consists of two HF amplification stages, frequency changer, separate oscillator, three IF stages, amplifying grid detector, output tube and heterodyne oscillator. A rotating turret carries the HF and oscillator tank circuits - 4 sets of 4 tank circuits each; inductance adjustment is by threaded iron cores in the antenna and HF plate coils and by a copper slug in the oscillator coils; parallel trimming is by variable ceramic capacitors and oscillator padding by fixed tubular ceramics.

Circuits are tuned by a 4-gang variable capacitor of die-cast construction with ball bearings and ceramic insulation. The heterodyne oscillator is controlled by a three-position switch - one for "off" and other two giving notes of 1000 KHz below and 1000 KHz above the null point. A 900 KHz filter that permits CW signals to be received, in spite of interference, consists of a tuning iron core choke in the 2nd detector plate circuit that can be inserted by switch "Tonsieb".

AVC is extremely effective, rise out of output being 2 DB between 5 microvolts and 50 millivolts. The first IF coupling comprises a pair of tuned circuits coupled through a quartz crystal and a reactive link having common inductance and a small capacitance. A small 2-gang variable capacitor de-tunes the two circuits in opposite directions. The receiver has ample total gain; when tested on bandwidth of 10 KHz using a dummy load of 100 Ohms, the modulated input (30% modulated) for signal/noise ratio or 20 DB varied between 10 and 16 microvolts. The corresponding figure on a narrow bandwidth and without the filter is 4 to 7 microvolts or approximately 1 microvolt on CW