The bombers typically used several ARC-5 command radio transmitters and receivers. These were pre-tuned before takeoff, and that's why there are several of them: one for each frequency used for the flight. For long distance, the radio op.,when one was aboard, had either BC342 or BC348 receivers, and I don't remember which transmitter, but higher power than the ARC-5 sets. The radio op. could transmit either on AM (voice) or CW (Morse code)
ARC-5 command sets were plentiful in the '50s and 60s, and sold for about $5, new or almost new. We converted them to work on the Amateur Radio bands. They were normally powered by a dynamotor (motor/generator) but we built power supplies running from 120 Vac.
Floyd