It was “The Jeep of the radio world” as dubbed by a former Special Forces radio operator in Vietnam
They were used extensively from the early 1950’s (as the RS-1) through the 1970’s and beyond by the CIA, Special Forces, other US military and allied units worldwide.
transmitter output of between 10 – 15 watts, a built in key that works well, versatile power supply options and a sensitive receiver, they did the job. The transmitter covered the frequency range of 3 to 22 MC in 4 bands; the receiver covered 3 to 24 MC in 4 bands.
The GRC-109 started production about 1961. Compared to the RS-1, GRC-109 units have more date-coded components, and more documentation is available to support those dates. GRC-109A units have a 1969 contract date on the ID plate.
In late 1961, the CIA organized a number of 12-man Special Forces teams to work with Montagnard tribesmen, and used the RS-1 for communications. Meanwhile, the Army's chief signal officer arranged for the RS-1 to be adopted for military use and renamed the GRC-109. Even though the Army had many RS-1 sets in use already, giving it an Army identifier would have simplified logistics. By late 1962, the Special Forces team network had 24 stations. The GRC-109 set in each "A detachment" SF camp was kept in a sandbagged bunker, with several antennas installed. The antennas were a target of Viet Cong raids, but for emergencies, they found that a longwire buried 18" underground in bamboo pipes could be used. [Ref. 6]
The GRC-109 became a standard issue radio to all combat units in forward areas after 1965. It was included in the inventory of all fire bases, and was at least used as a backup radio. Even though Special Forces had access to the latest high-tech radios, by the mid-1970's many units had adopted the GRC-109 as their primary long-range radio. It was rugged, reliable, and maintainable in the field, and offered several power supply options. The newer radios tended to require specialized batteries which were often not available in the field.
Estimated dates are summarized as follows: