TM 1-1510-225-10
3-5
(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 -22D 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 3-1 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 25.00 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.
Table 3-1. VHF Communications Transceiver Control UnitChannel/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
