Burst Encoders
The German RT3, or Rapid Transmitter 3, was used by the West German spies with the SP15 transmitter. This was first deployed in 1958 and has serial number 1000.
The Russian Burst Encoder was first introduced in the 1960s during the height of the Cold War. It was one of the first uses of magnetic tape, in this case using permanent magnets to rotate by the tape to encode the signal. There was no electrical or battery connection needed.