controller. Provides airborne VHF communications
from 118.000 through 151.975 MHz and is operated by
two CTL-22D transceiver control units.
The solid-state transceiver includes capture-
effect automatic squelch to help prevent missed radio
calls, plus audio leveling and response shaping to
insure audio quality. Transmitter sidetone comes from
detected transmitter signal, and is therefore a reliable
check of transmission quality. Each VHF transceiver
is powered through its respective circuit breaker,
placarded VHF # 1 or VHF # 2, located on the circuit
(VHF-22D). All operating controls for the transceivers
are located on the CTL-22 transceiver control units.
Refer to Figure 3-2.
(1) Active Frequency Display. Displays the
active frequency (frequency to which the transceiver is
tuned) and diagnostic messages.
(2) Transfer/Memory Switch. This switch is a
three-position spring-loaded toggle switch placarded
XFR / MEM, which, when held to the XFR position,
causes the preset frequency to be transferred up to
the active display and the transceiver to be returned.
The previously active frequency will become the new
preset frequency and will be displayed in the lower
window. When this switch is held to the MEM position,
one of the six stacked memory frequencies will be
loaded into the preset display. Successive pushes will
cycle the six memory frequencies through the display
(...2, 3, 4, 5, 6, 1, 2, 3...).
(3) Store Button. This button, placarded
STO, allows up to six preset frequencies to be
selected and entered into the control unit's memory.
After presetting the frequency to be stored, push the
STO button. The upper window displays the channel
number of available memory (CHAN 1 through CHAN
6) while the lower window continues to display the
frequency to be stored. For approximately 5 seconds,
the MEM switch may be used to advance through the
channel numbers without changing the preset display.
Push the STO button a second time to commit the
preset frequency to memory in the selected location.
After approximately 5 seconds, the control will return
to normal operation.
(4) Frequency Select Knobs. Two concentric
tuning knobs control the preset or active frequency
displays. The larger knob changes the three digits to
the left of the decimal point in 1-MHz steps. The
smaller knob changes the three digits to the right of
the decimal point. The knob is Rate Aided. The
faster the kHz knob is turned, the more channels will
be skipped. A single click of the kHz knob will either
increase or decrease the channel by a single channel.
(5) Active Button.
placarded ACT, enables the tuning knobs to directly
tune the VHF transceiver, when pressed and held for
2 seconds. The bottom window will display dashes
and the upper window will continue to display the
active frequency. Pushing the ACT button a second
time will return the control unit to the normal two-
(6) Test Button. This button, placarded
TEST, initiates the transceiver self-test diagnostic
routine. Self-test is active only when the TEST button
(7) Light Sensor. This built-in light sensor
automatically controls display brightness.
(8) Volume Control. The volume control is
concentric with the power and mode switch.
1. Active Frequency Display
2. Transfer/Memory Switch
3. Store Button
4. Frequency Select Knobs
5. Active Button
6. Test Button
7. Light Sensor
8. Volume Control
9. Power and Mode Switch
10. Annunciators (MEM TX)
11. Preset Frequency Display
12. Compare Annunciator
Figure 3-2. VHF Communications Transceiver