ON/OFF Switch
Controls the power supply to the Radio.

BFO Switch
When selected, the Beat Frequency Oscillator mode becomes active, provided the ADF receiver is selected.

STBY NAV Switches
( VOR, ILS, MLS & ADF )
When the NAV switch is selected, enables tuning of the selected navaid via the frequency selector knobs.

NAV Switch ( Guarded )
When pressed the radio navigation back-up mode engages.

SEL Indicator
Illuminates on both RMPs when a transceiver normally associated with an RMP is tuned by another RMP.

Radio Selection Switches
( VHF, HF & AM )
When pushed, the ACTIVE window displays the tuned frequency and the STBY/CRS window displays the Standby frequency.

Transfer Switch ( Arrow )
When pushed, exchanges the active and standby frequencies, and tunes the new active frequency.

Frequency Displays Windows

• ACTIVE - Shows the active frequency of the selected radio (which is identified by the illuminated radio selection key).
• STBY/CRS - Displays the NAV course or standby radio frequency. This frequency is activated by pushing the transfer switch, and is changed by rotating the frequency selector knobs.

Frequency Selector Knob
Selects the course or standby radio frequency. Displayed in STBY/CRS window.

Inner knob controls decimal values.