The Telex SR-400 Receiver is a synthesized receiver which operates on 17 channels in the 72 to 76 MHz Band. The SR-400 is designed to be used with the Telex PST-170, and ST-300 transmitters.
The Telex ST-300 and PST-170 Transmitters are equipped with E.D.R., Enhanced Dynamic Range (companded) audio. This mode greatly improves the audio signal to noise ratio when used with the Telex Model SR-400 receiver. The E.D.R. mode must be selected on both the transmitter and receiver to be effective.
The SR-400 Receiver uses two AA alkaline batteries. 16-20 Hours of operations can be expected from alkaline batteries and 8-10 hours on nickel-cadmium batteries.