automatic squelch

A squelch ensures that a receiver amplifier does not get inundated by unwanted noise when the transmitter signal is not present. Such a device is essential for communications equipment, since the transmitter is switched off between transmissions. If the receiver does not possess a squelch circuit, the noise literally bursts out of the loudspeaker during these breaks. Besides the straightforward construction and calibration, a major advantage of the automatic squelch circuit described here is the fact that you do not have to be an expert to install it into the audio section of the receiver.