The UHF transmitter-receiver provides twoway communication between aircraft and ship, aircraft and shore or between aircraft on any one of 7000 frequency channels spaced at 25 KHz intervals in the frequency range of 225.000 to 399.975 MHz. It also contains a fixed tuned guard receiver.

Electrical power is supplied by the No.1 radio bus at 28 VDC through a UHF circuit-breaker on the radio circuit-breaker panel.

The set is a self-contained console mounted unit, marked “UHF” (Figure 1-10-11) on the radio and navigation control panel. It permits selection of any one of 20 preset channels or the guard channel within the specified frequency range. Manual control permits selection of any one of 7000 channels. The function of controls are as follows:

a. The function selector has four positions with the following functions;

(1) OFF. The UHF is disabled.

(2) MAIN. The UHF main receiver and transmitter are enabled.

(3) BOTH. The UHF main receiver and transmitter as well as the guard receiver are enabled.

(4) ADF. Inoperative.

b. The mode selector has three positions with the following functions;

(1) MANUAL. The set may be tuned to the desired frequency using the five manual frequency knobs.

(2) PRESET. One of 20 preset channels may be selected using the channel selector knob.

(3) GUARD. The guard receiver is disabled and the main receiver and transmitter are automatically tuned to 243.000 MHz.

c. The VOL control should be adjusted as desired. Receiver volume to suit individual requirements may then be controlled by the RAD VOL control knobs at individual ICS transmitter selector panels.

d. The TONE button allows transmission of a 1020 Hz tone on the selected frequency. SQUELCH OFF/ON disables or enables the squelch circuit of the main receiver.