UHF Radio

CHAPTER ELEVEN

T-34C AIRCRAFT SYSTEMS FAMILIARIZATION

WORKBOOK

UHF Radio

The T-34C communications radio, also referred to as a UHF transceiver, provides line-of-sight

transmission and reception of radio signals in the UHF range of 225.0 to 399.95 Megahertz

(MHz). Communication can cover a distance of approximately 50 NM, but it works on a "line-of-

sight" basis (which means you cannot communicate over the horizon).

The components include the transceiver located in the avionics compartment, the blade type

antenna on the top of the fuselage just aft of the aft cockpit, the control panel on each left console,

and the transmit switch on each PCL (Figure 11-1). On the control panel, the FUNCTION

selector switch is used to select MAIN or BOTH for normal operations. This will allow the pilot

to transmit (using the toggle switch on the PCL) and receive on any selected frequency in the

UHF range. The BOTH position provides the additional capability of "monitoring" (listening to)

GUARD (emergency frequency 243.0 MHz) and is the normal position for flight.

Selection of the desired frequency is done by using a combination of the mode selector knob and

manual frequency selectors or preset channel selector knobs. With the Mode Selector in

MANUAL, the frequency/channel indicator (light emitting diodes - LED readout) will indicate

the frequency selected using the four Manual Frequency Selectors. If PRESET is chosen, the

frequency/channel indicator will display a number - "1" to "20" - representing a commonly used

selectable preset frequency. The READ position displays the frequency of the selected preset

channel. The GUARD position automatically sets the UHF radio to transmit and receive on the

emergency frequency 243.0 MHz.

Additional switches on the panel include a VOLume knob, SQuelch ON switch to remove static,

LAMP TEST button to check the LED filaments, a DIM control, and a TONE button to confirm

operation.

The radio will operate on the frequency/channel of the control panel in the cockpit having avionics

control and both front and aft cockpit indicators will display that frequency or channel. The pilot not

possessing avionics command can still transmit or receive, alter his/her own volume, and use the

TONE and LAMP TEST buttons. Simply put, the pilot possessing avionics command will control the

transceiver in the avionics compartment and both cockpit panels serve as repeaters of the transceiver.

The automatic direction finding (ADF) position is not functional.

VHF Radio

In 1998, the T-34C added a VHF transceiver as a second means of communication (Figure 11-4).

Located in the front cockpit map case, this radio works in the VHF frequency range between 118.000

and 136.975 MHz, and has a range in distance of approximately 50 miles. The VHF antenna is a wire

antenna located on the bottom of the fuselage between the forward and after transponder antennas.

11-6 AVIONICS