TM 55-1510-215-10
NOTE
3-9. UHF Command Set (AN/ARC-51BX) (If installed).
No traffic will be passed if the
interrupted tone is still heard from
provides two-way amplitude modulated (AM) voice
pressing
and
releasing
the
communication within the frequency range of 225./0 to
microphone switch.
399.95 MHz for a distance range of approximately 50
miles line-of-sight. Channel selection is spaced at 50
5. Microphone switch - Press (do not
kHz intervals.
Additionally, a separate receiver is
talk). Wait until beep is heard, then
incorporated to provide monitoring capability for the UHF
speak into microphone.
guard frequency (243.0 MHz). The audio output of the
UHF set is applied to the audio control panel where it is
(5) Homing operating procedure.
made available to the headsets. Power for the UHF
command set is fed through the 50-ampere AVIONICS
NOTE
NO. 1 and AVIONICS NO. 2 circuit breakers on the
copilot's circuit breaker panel. The set is protected by a
Accuracy of the FM liaison set has
15-ampere circuit breaker, placarded UHF, located on
been verified on the following
the copilot's subpanel.
frequencies only: 32.00, 34.50, 38.90,
and 39.50 MHz.
b. Controls and Functions.
1. Mode selector (FM COMM control
(1) Preset channel indicator. Indicates the
panel) - HOME.
preset channel in use when the mode selector is in the
PRESET CHAN position.
2. Frequency selectors (FM COMM
(2) SQ DISABLE switch.
Turns squelch
control panel) - Select.
circuit on or off.
3. VOL control (FM COMM control
(3) VOL. Control. Adjusts volume.
panel) - As required.
(4) Function switch. Selects type of operation
4. Pilot or copilot's COURSE IND
and turns set off.
switch (instrument panel) - HOME.
(5) Manual frequency selector. Selects the
operating frequency when the mode selector is in the
NOTE
MAN position.
FM homing steering signals can be
(6) Frequency.
Indicates the operating
displayed only on one course
frequency of the UHF receiver and transmitter when the
indicator-selector) at a time.
mode selector is in the MAN position.
(7) Mode selector.
Determines operation
5. Course deviat ion indicator (pilot or
mode.
copilot's course indicator-selector) -
(a) PRESET CHAN. Permits selection
Read lateral deviation from horning
of one of 20 preset channels.
course.
(b) MAN. Permits frequency selection
6. Glideslope
indicator
(pilot
or
by means of manual frequency selector controls.
copilot's course indicator-selector) -
(c) GD XMIT. Automatically tunes to
Read relative signal strength.
the guard channel frequency.
Indicator will deflect towards the
bottom for a weak signal and move
toward the center position as the
(8) PRESET CHAN selector.
Selects the
signal strength increases.
desired preset channel when the mode selector is in the
PRESET CHAN position.
(6) Shutdown procedure.
c. UHF Command Set Operation. The function
1. Mode selector (FM COMM control
switch must be ON for the following procedures.
panel) - OFF.
(1) Receive operating procedure.
2. POWER ON switch (CIPHONY
control-indicator) - OFF.
1. Mode selector - As required.
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