KO-5 was a shore based device located at major communications
stations. Originally built for the US Army to encrypt facsimile in the
early 1950's and later adapted to encrypt 16 channels of 100 WPM
teletype circuits simultaneously. It was tube type machine about 20 feet
long, using magnetic core memory, pre-punched paper key tape to load the
key, Morse code communications for starting and synchronizing, and
commonly called 'The Horse" by US Navy personnel. It's 16 teletype
channels were multiplexed with the aid of an FGC-60 tone converter. It
was used primarily for long distance high frequency full duplex
communications.
Contributor: Art Richie