Plugs connect power, antenna, key and mike.
The Collins KWM-1 is the granddaddy of all SSB transceivers, the very first SSB transceiver produced anywhere. The KWM-1 arrived in 1957 with lots of fanfare. Single sideband was the up and coming mode, but most hams were using homebrew transmitters or small commercial boxes with lots of homemade accessories for both receiving and transmitting. Made fo rlots of clutter in the shack. As for mobile, again it was separate units taking up lots of car space.