AIRPLANE
OPERATIONS
MANUAL
NAVIGATION AND
COMMUNICATION
MARCH 30, 2001
2-18-22
Page
3
Code
01
7 - POWER AND MODE KNOB
OFF - Turns off the system.
ON - Turns on the system.
SQ OFF - Disables the receiver squelch circuits. Use this position
to set volume control or, if necessary, to try to receive a
very weak signal that cannot operate the squelch
circuits.
8 - ANNUNCIATORS
− The COM control contains MEM (memory) and TX (transmit)
annunciators.
− The MEM annunciator illuminates whenever a preset frequency
is being displayed in the lower window.
− The TX annunciator illuminates whenever the VHF-22A is
transmitting.
9 - PRESET FREQUENCY DISPLAY
− Displays the preset (inactive) frequency and diagnostics
messages.
− The frequencies displayed on the COM control show only five of
the six digits.
10 - COMPARE ANNUNCIATOR
− ACT momentarily illuminates when active and preset
frequencies are being switched.
− ACT flashes if the actual radio frequency is not identical to the
frequency shown in the active frequency display.
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