Figure 3-1.Voice system.
The handset converts acoustical energy (your voice) to electrical energy for use in modulating a
radio transmitter. It also converts electrical energy to acoustical energy for reproduction of a received
signal. When the push-to-talk button is depressed on the handset, the dc keying circuit to the transmitter is
closed, placing the transmitter on the air.
Handsets are normally connected to a radio set control unit.
RADIO SET CONTROL UNIT
The radio set control unit shown in figure 3-2 provides a capability to remotely control some
radiophone transmitter functions and the receiver output. Some of the controls are used for turning the
transmitter on and off. Others are used for voice modulating the transmission (or keying when cw
operation is desired). You can even control the audio output level of the receiver and silence the receiver