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1960s Military Morse Magazine Recording Tape MA9 / GRA71 For An Electromechanical Burst Encoder

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1960s Military Morse Magazine Recording Tape MA9 / GRA71 For An Electromechanical Burst Encoder

This is a 1960s Military Morse Magazine Recording Tape MA9 / GRA71 For An Electromechanical Burst Encoder, which forms part of covert surveillance (spying) radio communication history.

It is in very good used condition but I don't know whether or not it is working, and is being sold as a collectible for display only.

This small device, the MA-9 or CA-3B, was used to pre-record a clandestine encrypted message on the mechanical tape cartridge before transmitting using the 'keyer,' which we also have available to purchase. 

Manufactured by Arvin Industries Inc., serial no. 2761

The MA-9 cartridge uses industrial grade ferro-audio tape. It holds approximately 12.5 feet of tape sufficient for 150 5-letter words recorded as a series of pulses in morse code.

This is the military version of the magazine in a black box; the whole set was designated GRA71. It was used with USA army radios and CIA spy radio sets such as the AN/PRC-64A and RS-1 (AN/GRC-109).

A very rare item and often missing from the GRA71 burst coder spy set.

The Electromechanical Burst Encoder was invented by Stenographic Machines in Skokie, Illinois, USA, for the CIA (Central Intelligence Agency). It allowed pre-recorded messages to be sent, in morse code, at very high speeds. This was an essential requirement ensuring that the operator was on air for the minimum time possible to prevent detection by RDF (Radio Detection Finding).

Please click on the following link for more radio communication accessories and Militaria.


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