R392/URR HF Receiver

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General Description

The R392 is a communications receiver used by the US Army after 1954. It is normally used with the T-195 transmitter as the AN/GRC-19 for use on vehicles or in a portable station capacity. The set has many common features of the Collins R390/R391 series. (Even though it is a mobile receiver it weighs 52 pounds and is almost as heavy as the other sets!)

Technical Data

The set is a multi-conversion superheterodyne tuning from 500kc to 32 mc/s. The conversion scheme varies according to the frequency ranges selected. It features a supply voltage of 28vdc, using series string heaters as well as numerous 28v filament tubes. Rather unusually, the high tension is derived directly from the 28v supply line. As is the usual practice with this receiver series, the set effectively comprises 31 bands, each 1 mc wide. There is no provision to tune the frequency range 0 - 500kc, although the dial indicates this.

Radio Receiver R392/URR is capable of very high performance. It is mechanically very complex as is usual for many post war Collins military designs. The set uses many locally unobtainable tubes and has the potential to be a difficult piece of equipment to maintain. There are several removable modules including a precision PTO (Permeable Tuned Oscillator) as the main frequency tuning component. All other coils are tuned by ferrite slugs connected to a bar (slug rack) which simultaneously tunes all coils. The slugs are used to tune the inductors (instead of a tuning capacitor) to give a linear frequency response. The two main frequency tuning knobs are connected to mechanical digital counters to indicate megacycles and kilocycles, each separately controllable.

The R392 to the best of my knowledge has never been used by our armed services. The display set was brought into the country by a visiting American. The set does not have provision for SSB, although riding the RF/AF controls enable SSB to be decoded on CW. The set would be suitable for short wave listeners equipped with heavy duty tables! Audio output is at 600 ohms and quite adequately drives a speaker. There is also headphone output available. Power input is 28 vdc at 4 amps.