The Electrocom 402 DL Terminal Unit. Solid state except to the CRT tuning display, this TU features adjustable mark and space frequencies via the thumb wheel switches. Has a loop output (naturally), autostart, and copy on mark. Also has a switch position for SEND, and an unoccupied slot for a pcboard for that purpose. Sure wish I had that board!
It's a nice TU, although I've had to replace 741 op-amps in both units owned here. Fortunately, they are socketed.