TM 1-1510-218-10
3C-9
(9) Power and Mode Switch. The power
and mode switch contains three detented positions.
The ON and OFF positions switch system power.
The SQ OFF position disables the receiver squelch
circuits.
(10) Annunciators. The transceiver control
unit contains a MEM (memory) and a TX (transmit)
annunciator. The MEM annunciator illuminates
whenever a preset frequency is being displayed in
the lower window. The TX annunciator illuminates
whenever the transceiver is transmitting.
(11) Preset Frequency Display. Displays
the pre-set (inactive) frequency and diagnostic
messages in the lower window.
(12) Compare Annunciator. An annunciator,
placarded ACT, momentarily illuminates when
frequencies
are
being
changed.
The ACT
annunciator flashes if the actual radio frequency to
which the transceiver is tuned is not identical to the
frequency shown in the active frequency display.
If two communications transceivers in
the same aircraft are tuned to stations
carrying
the
same
voice
message,
attempting to listen to the received
signals from both simultaneously could
result in a great reduction in the actual
audio volume.
c. Operating Procedures. The 8.33 kHz capable
CTL -22C shows the VHF COM frequency as a channel
frequency using all six digits of the display. There are no
8.33 kHz channels above 136.992 MHz. The last
“channel name” is 136.990, which is an actual frequency
of
136.9917
MHz.
Table
3C-2
shows
the
channel/frequency scheme for the 180.000 to 136.992
MHz range. While the CTL is in the frequency range of
137.000 to 151.975 MHz, the unit behaves the same as
a 25 kHz only unit.
NOTE
It is possible that erroneous operation could
occur without a fault indication. It is the
responsibility of the pilot to detect such an
occurrence by continually assessing the
reasonableness of operation as displayed on
the associated transceiver control unit and
by the quality of received signals and
transmissions.
(1) Equipment Startup. The transceiver and
the control unit are turned on by rotating the power and
mode switch on the transceiver control unit to the ON
position. When the transceiver is first turned on, it
sounds a brief tone while the microprocessor checks its
own memory. If there is a memory defect the tone
continues, indicating that the transceiver can neither
receive nor transmit. After the memory check, the
transceiver control unit will display the same active and
preset
frequencies
that
were
present
when
the
equipment was last turned off.
Table 3C-2. VHF Communications Transceiver Control Unit Channel/Frequency Scheme
(118.000 To 136.992 MHz Range)
FREQUENCY
SPACING
(kHz )
CHANNEL
NAME
(DISPLAYED)
FREQUENCY
SPACING
(kHz )
CHANNEL
NAME
(DISPLAYED)
118.0000
25.00
118.000
118.0750
25.00
118.075
118.0000
8.33
118.005
118.0750
8.33
118.080
118.0083
8.33
118.010
118.0833
8.33
118.085
118.0167
8.33
118.015
118.0917
8.33
118.090
118.0250
25.00
118.025
118.1000
25.00
118.100
118.0250
8.33
118.030
118.0333
8.33
118.035
118.0417
8.33
118.040
118.0500
25.00
118.050
136.9750
25.00
136.975
118.0500
8.33
118.055
136.9750
8.33
136.980
118.0583
8.33
118.060
136.9833
8.33
136.985
118.0667
8.33
118.065
136.9917
8.33
136.990
WARNING
