was a hand-held radio transceiver
used by US Signal Corps
in World War II
. It is popularly referred to as a walkie talkie
although it was originally designated a "handie talkie".
The SCR-536 is often considered the first of modern hand held, self-contained, "handie talkie" two-way radios
. It was developed in 1940 by a team led by Don Mitchell, chief engineer for Galvin Manufacturing (now Motorola
) and was the first true hand-held unit to see widespread use. By July 1941, it was in mass production, and at war’s end, 130,000 of them had been manufactured. It was the smallest of all the two-way radio equipment used by the Signal Corps at the time.
In November 1942, the SCR-536 received coverage in the amateur radio magazine QST. It appeared on the cover as well as in Signal Corps advertising, and was featured as part of an article on the Signal Corps. “Smallest field unit of the Signal Corps,” a photo caption read, “it is not much larger or heavier than a conventional handset.”
Today the SCR-536 is often restored and operated by vintage amateur radio enthusiasts and military radio collectors.
The SCR-536 incorporated five vacuum tubes
in a waterproof case. There was no power switch on the SCR-536. The operator pulled out or pushed in the antenna
on the top to turn the radio on or off. The power was supplied by a BA-37 1.5 volt dry battery for the filament supply and a 103.5 V BA-38 battery for plate supply. Battery life was about one day of normal use. The SCR-536 weighed 5 pounds
with batteries and 3.85 lb without batteries (2.3 and 1.75 kg). The unit operated in AM
voice mode between 3.5 and 6.0 MHz
frequency range on any one of 50 channels. Plug in crystals and coils were used to control the frequency of the receiver and transmitter. The antenna was a 40 inch telescoping rod that slid into the case. The SCR-536 had an RF
output power of 360 milliwatts
. The range of the unit varied with terrain; from a few hundred feet, to approximately one mile over land, and 3 miles over water.
Under the Army Nomenclature System, the BC-611 transceiver was the core component of the SCR-536 Signal Corps Radio set. The Signal Corps technical manual number was TM 11-235.