Circa 1958 Cold War-era clandestine RT-3 electromechanical burst encoder, developed by Wandel & Goltermann for the German Federal Intelligence Service (BND). The device measures 4.25″ x 3.5″ x 1.5″, and is marked on the case with serial number "RT3 9501." The heavy-duty case has a spring-loaded panel that opens to reveal the mechanical memory cylinder, which rotates to reveal 25 horizontal bars, each with a tab moveable to ten positions. The cylinder crank is stored in a cleverly milled-out cavity in the bottom of the unit. A user could load 25 characters into this mechanical memory, and the unit would transmit them at high speed in Morse code, which made interception and direction-finding very difficult. In very good to fine condition. Accompanied by a modern operating manual detailing the history and function of the RT-3.