Abstract: In a transmitter or transceiver having alternately selectable transmission frequency channels, frequency selection switching is actuable for switching the transmitter from channel to channel and for stopping at the desired channel. A device, such as a microphone push-to-talk switch actuates the transmitter. Lock-out circuitry, interconnected with the transmitter actuating device and frequency selection switching, precludes simultaneous transmission and channel switching. In one embodiment, operating potential is removed from channel switching circuitry when the transmitter is in actuated condition and such channel switching circuitry is supplied operating potential only with the transmitter in its nonactuated condition. In further embodiments, frequency selection switching is disabled or blocked when the transmitter is actuated and only becomes enabled when the transmitter is deactuated.