NAVIGATION AND
COMMUNICATION
AIRPLANE
OPERATIONS
MANUAL
2-18-13
Page
2
Code
01
MARCH 30, 2001
TBCH CONTROLS AND INDICATORS
1 - SYSTEM INSTALLATION ANNUNCIATION
− Indicates to which Radio System the Tuning Backup Control
Head is connected.
2 - REMOTE TUNE ANNUNCIATION
− Indicates that radio is tuned from a source other than the Tuning
Backup Control Head.
− Presented only when the unit is strapped for NAV only or COM
only tuning.
3 - TUNING CURSOR
− Indicates which frequency may be changed by the Tuning
Knobs.
4 - NAV AUDIO ON ANNUNCIATION
− Indicates that the NAV audio is selected on.
5 - EMERGENCY MODE ANNUNCIATION
− Indicates when the unit has been selected to the Emergency
Mode, which inhibits RMU tuning capability.
NOTE: - This annunciation is not related to the emergency COM
frequency of 121.5 MHz.
6 - SQUELCH ANNUNCIATION
− Indicates that the squelch is opened by the SQ Switch.
7 - TRANSMIT ANNUNCIATION
− Indicates that the COM transmitter is ON.
8 - NAV AUDIO BUTTON
− Toggles NAV audio on and off.
9 - SQUELCH BUTTON
− Toggles the COM squelch on and off.
10 - TUNING KNOBS
− Change the frequency indicated by the tuning cursor.
− Inner knob changes the frequency decimal digits in steps of
0.025 MHz for VHF and 0.050 MHz for VOR/LOC.
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