R-353 Proton burst encoder and magnetic tape cassette, introduced in the Soviet Union in 1969 as part of the R-353 spy radio set. The burst encoder measures approximately 4″ x 3″ x 1.5″, and features a central black number dial similar to a rotary phone. Using a stylus stored inside the lid to rotate the dial, a message would be encoded onto magnetic tape. The tape cartridge measures 4″ x 2″ x 1″ and has two small fold-out cranks for winding the tape on its internal spools. Both pieces are painted in the original green/blue hammerite paint, one of two colors used for the R-353 Proton spy radio set. Both include their canvas transport bags.
Once encoded, the tape cartridge would be loaded onto an R-353 transmitter, which would broadcast the Morse code message at a very high speed (typically 250 WPM) in order to avoid interception and radio direction finding (RDF). The tape cartridge, with a pre-coded message, could also be placed as a dead drop—eliminating any possibility of exposing an agent through RDF.
