SCR-300

The SCR-300 was a portable radio transceiver used by US Signal Corps in World War II. This backpack-mounted unit was the first radio to be nicknamed a "walkie talkie".

In 1940, Motorola (then the Galvin Manufacturing Company) received a contract from the War Department to develop a portable, battery powered voice radio receiver/transmitter for field use by infantry units. The project engineering team consisted of Daniel E. Noble, who conceived of the design using frequency modulation, Henryk Magnuski who was the principal RF engineer, Marion Bond, Lloyd Morris, and Bill Vogel. The SCR-300 operated in the 40.0 to 48.0 MHz frequency range, and was channelized. It, along with mobile FM tank and artillery radios such as the SCR-508 (20.0 to 27.9 MHz) and the SCR-608 (27.0 to 38.9 MHz) marked the beginning of the transition from low-HF AM/CW to low-VHF FM for combat-net radio.

Although a relatively large backpack-carried radio rather than a handheld model, the SCR-300 was described in War Department Technical Manual TM-11-242 as "primarily intended as a walkie-talkie for foot combat troops", and so the term "walkie-talkie" first came into use.

The final acceptance tests took place at Fort Knox, Kentucky in Spring 1942. The performance of the SCR-300 during those tests demonstrated its capacity to communicate through interference and the rugged quality of the design. Motorola was to produce nearly 50,000 of the SCR-300 units during the course of World War II.

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