Beechcraft C-12C Operator And Technical Reference Manual page 295

(2) Receiver Operating Procedure.
1. Function switch – As required.
2. Frequency
frequency
channel
frequency selector controls.
The PRESET channel selector and manual
frequency selectors are inoperative when
the Mode Selector switch is set to GUARD.
3. VOL – Adjust.
4. SQUELCH – As required.
(3) Transmitter Operating Procedure.
1. Transmitter select switch located on
the audio control panel, Figure 3B-1 –
UHF position.
2. Microphone switch – Press.
(4) Shutdown Procedure. Function switch –
OFF.
d. Emergency Operation.
Transmission on emergency frequencies
(guard channel) shall be restricted to
emergencies only.
frequency of 121.500 MHz is also available
on the VHF command radio set.
1. Transmitter select switch located on
the audio control panel, Figure 3B-1 –
UHF position.
2. Mode selector switch – GUARD.
3. Microphone switch – Press.
3B-8. VHF COMMUNICATIONS TRANSCEIVERS
(VHF-22D).
a. Introduction. The VHF communications
transceivers are an 8.33 kHz channel spacing cable
system. The operation between the 25 kHz and 8.33
kHz modes is seamless. Within the space occupied by
each 25 kHz frequency exist three 8.33 kHz channels.
The 8.33 kHz "frequency" is referred to as a "channel"
not the actual frequency tuned. The channel scheme
avoids possible confusion associated with shared
25 kHz and 8.33 kHz frequencies. This method
– Select required
using either
selector or manual
NOTE
NOTE
An emergency
ensures that the equipment will always be operating in
the proper spacing mode and occurs automatically as
the user tunes the controller. Provides airborne VHF
communications from 118.000 through 151.975 MHz
and is operated by two CTL-22C transceiver control
units. Refer to Figure 3B-3.
preset
The solid-state transceiver includes capture-
effect automatic squelch to help prevent missed radio
calls, plus audio leveling and response shaping to
ensure audio quality.
from detected transmitter signal, and is therefore a
reliable check of transmission quality.
transceiver is powered through its respective circuit
breaker, placarded VHF 1 or VHF 2, located on the
circuit breaker panel.
b. VHF
(VHF-22C). All operating controls for the transceivers
are located on the CTL-22 transceiver control units.
Refer to Figure 3B-3.
(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
XF/MEM, which, when held to the XF position, causes
the preset frequency to be transferred up to the active
display and the transceiver to be returned.
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.
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.
TM 1-1510-218-10
Transmitter sidetone comes
Transceiver Operating
This button, placarded
Each VHF
Controls
The
3B-5