U.S.Army photo showing a display of the basic AN/GRC-46,
and identifying the major components.
The AN/GRC-46 is an AM set capable of simplex or duplex operations, transmitting and receiving Voice, CW Morse Code and RTTY RadioTeletype. The main components of the set are the T-195/GRC-19 Transmitter, operational from 1.5 to 20 mHz, the R-392/URR Receiver, operational from 0.5 to 32 mHz and the Teletype equipment which can send or receive printed messages. Teletype messages can be sent directly from either keyboard or they can be recorded on perforated tape for later transmission.
The primary purpose of this set is to provide Radio-Teletype communications between Company and Brigade level units. The set has a maximum output of 100 watts with a reliable range of 50 miles using a 15-foot whip antenna. Sky waves can extend the range up to several thousand miles, but are unrelaible and unpredictable. It is shelter mounted and carried in the bed of a 3/4 ton M37B1 cargo truck. Being designed to be set up for use in a fixed location, it would rarely be used with the vehicle in motion, and then only for voice communications from the truck's cab. In normal operations it uses the whip antenna but it can also use a longwire or any of several other antenna types. With additional equipment, the transmitter and receiver alone can be operated from remote locations, up to two miles away from the set, in voice or CW modes.
Power requirement is 27.5 VDC obtained from the vehicle's 100 Amp power supply, or from a 1.5 KW gasoline generator which is carried in a M101A1 trailer pulled by the M37B1. The teletype equipment is powered by 115 VAC motor generators that are, in turn, powered by the vehicle's electrical system or the DC generator.
The AN/GRC-46(A) and AN/GRC-46(B) variants added security and cryptographic equipment for secure operations. A version of the AN/GRC-46 was used in armoured vehicles and is designated AN/VRC-29.