The SCR-694 was a portable two way radio set

Signal Corps Radio

Signal Corps Radios were U.S. Army military communications components that comprised "sets". Under the Army Nomenclature System, SCR initially designated "Set, Complete Radio," and later "Signal Corps Radio," though interpretations have varied over time....

 used by the U.S. military during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

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History

The SCR-694 replaced the SCR-284 and was later replaced by the AN/GRC-9. Designed to provide communication between moving or stationary vehicles or as a portable field radio set, the SCR-694 was originally intended for use by mountain troops and airborne forces

Airborne forces

Airborne forces are military units, usually light infantry, set up to be moved by aircraft and 'dropped' into battle. Thus they can be placed behind enemy lines, and have an ability to deploy almost anywhere with little warning...

 but soon became the Army-wide standard at battalion

Battalion

A battalion is a military unit of around 300–1,200 soldiers usually consisting of between two and seven companies and typically commanded by either a Lieutenant Colonel or a Colonel...

 level.

Specifications

The SCR-694 was designated as "Radio set, Portable/Vehicular" consisting of the BC-1306 transmitter/receiver

Transceiver

A transceiver is a device comprising both a transmitter and a receiver which are combined and share common circuitry or a single housing. When no circuitry is common between transmit and receive functions, the device is a transmitter-receiver. The term originated in the early 1920s...

 capable of AM

Amplitude modulation

Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...

 and CW

Continuous wave

A continuous wave or continuous waveform is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off...

 mode operation between 3.800 to 6.500 MHz. Ranges up to 15 miles on voice and up to 30 miles on morse code

Morse code

Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...

 between moving vehicles were reported. Crystals

Crystal oscillator

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency...

 used in the transmitter operated at one half of the transmitting frequency. The set used vacuum tube

Vacuum tube

In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

s and operated from 6, 12 or 24 Volts DC supplied by a PE-237 Vibrator Power Unit. Optional accessories could include a hand crank generator with seat, antenna system, spares tube kit, canvas bags, and Jeep mounting plates. According to military manual TM 11-230C, the net weight of the set was 191.5 pounds

Pound (mass)

The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

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External links

• http://www.youtube.com/watch?v=LACLE6YTV28&feature=related training film
• http://www.olive-drab.com/od_electronics_angrc9.php
• http://www.gordon.army.mil/ocos/Museum/ScrComponents/scrPart1.asp SCR list