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.
The radio's case has no vents (with proper connectors the radio is immersion proof). Usually the inside of these radios is pristine no matter how ugly the outside may be!
Army TM 11-858, "RADIO RECEIVER R-392/URR"
"Communications Receivers, The Vacuum Tube Era 1932-1981", 3rd Edition, by Raymond S. Moore
Photo by Carl Battista, KB9ZIS
Photo by Giorgo Fontana, IN3IEX
R-392 Technical Data and Performance
R392 LINE DRAWING, B&W 25K GIF, 800x800.
Tom Norris has graciously provided photos of the inside top and bottom, plus the almost always missing special tools of the R-392.
Color R-392 photo by Keith, KK5FE, 68K bytes, with good detail.
Barry Hauser bought a completely solid-stated R-392 which also runs on 12 volts vice 28. Here are photos of the front panel and the IF/AF/PTO/Calibrator modules. All tubes have been replaced by either single transistors or small IC modules.
Mike Dinolfo has a nice R-392 web page, with details on component replacement and modifications.
More R-392 images from Google Image Search
A Japanese R-392? Now with even more photos/diagrams!
The solid-state son of R-392? The Collins R-864. New R-864/R-392 comparison photo.
The Marine Corps answer to the R-392, the R-808.