The R-392/URR was designed by the Collins Radio Co. and, like the R-390, produced by Collins and other manufacturers including Stewart-Warner and Western Electric on several contracts from 1950 to 1963. The receiver uses the same conversion scheme as the R-390, but is ruggedized and repackaged for mobile use. The R-392 was often used in conjunction with the T-195 transmitter as part of the GRC-19 radio set.
To quote the manual, Radio Receiver R-392/URR is a high-performance, compact, rugged receiver designed primarily for vehicular use. The receiver provides reception of radiotelegraph, voice, and single-channel, frequency-shift radioteletype signals within a continuous frequency range from 500 kilocycles to 32 megacycles. The receiver is immersionproof and is sufficiently rugged to withstand parachute delivery when mounted in a 1/4 ton, 4x4 truck prepared for parachute drop.
The radio operates directly from a 24-28 volt vehicular electrical system with no voltage converters of any kind -- tube filament and plate voltage is taken directly from the DC input. The receiver requires 3 amps of current at 28 volts. The tubes are a mixture of 6, 12 and 26 series (the series refers to the filament voltage). The filaments of the 6 and 12 volt tubes are wired in series combinations across the supply voltage, while all the 26 volt tube filaments are in parallel.