The VHF/AM system provides two-way voice communication in the frequency range of 116.0 to 151.975 MHz in 25 KHz increments for a total of 1440 frequencies. The system incorporates a 20 watt transmitter which has a continuous duty cycle. The VHF/AM is protected by a circuit-breaker marked “VHF AM” on the DC portion of the radio circuit-breaker panel. The system consists of three components: an antenna, a transmitter-receiver and a set control.

The antenna is a combined VHF and UHF antenna mounted on the port side of the lower fuselage just aft of the internal ASW stores chute (Figure 1-9-1). This antenna is shared with the UHF when the lower antenna is selected. When the upper is selected for the UHF antenna, the VHF/AM remains connected to the lower antenna.

The VHF/AM transmitter-receiver is located on a shelf immediately above the HF transmitter-receiver on the port side of the cabin just aft of the troop seat.

The VHF/AM set control (Figure 1-10-15) is located on the radio and navigation control panel at the bottom right. The set control permits selection of frequencies between 116.0 and 151.975 MHz in 25 KHz steps. There is no guard receiver incorporated and there are no preset channels. All frequencies are selected manually. The function of controls are as follows:

a. The power switch has three positions with the following functions;

(1) OFF. No power is applied to the system.

(2) PWR. The set is turned on and receives 28 VDC from the essential bus, the receiver is receiving on the selected frequency and the transmitter is on standby.

(3) TEST. The receiver squelch is disabled and an increase in receiver noise will be heard in the head-set.

b. The volume control is a rotary knob marked “VOL” which should be adjusted as desired.

c. The MHz control is a rotary switch concentric with the power switch which changes frequency in one MHz steps as indicated in the frequency readout window.

d. The KHz control is a rotary knob concentric with the volume control which changes the frequency in 25 KHz steps as indicated in the frequency readout window.