[GreenKeys] Western Union 7C tape transmitter?

[Jim Haynes]

Western Union had a number of different models of tape transmitters that
were basically electromagnet-stepped and parallel wire output.  One
important use was in time-division multiplex, where they used a big
faceplate distributor with rotating brushes to put the signals on to
the wire, and a contact on the distributor advanced the tape stepping
magnet at an appropriate time.  A bunch of these came into amateur hands
as the old mux systems were phased out.  W6NRM and probably others
devised electronic transmitting distributors to adapt them to single
channel start-stop operation.