TM 11-5841-287-12
Table 2-2 Uhf Radio Control Controls and Indicators-Continued
Table 2-2 Uhf Radio Control Controls and Indicators-Continued
Control or indicator
Function
Control or indicator
Function
Hundreds switch
selects operating frequency in 100-
(Set to WB at all times )
MHz steps
SQ-MN switch
Not operable (NOTE Squelch
Ten switch
Selects operating frequency in 10-
adjustment is performed
MHz steps
using the SQUELCH-MAIN
Units switch
Selects operating frequency in 1-
control on the uhf receiver-
MHz steps
transmitter front panel )
Tenths switch
Selects operating frequency in 0.1-
SQ-GD switch
Not functional
MHz steps
PRESET switch
Stores selected frequency in
Hundredths/thousandths
Selects operating frequency in 0.025
selected preset channel
switch
MHz steps
Indicator lamp display (red)
LED display of preset
BW (NB/WB) switch
Used to select wideband or narrow-
channel frequency
band selectivity of main receiver
Volume control
Not functional
Section II. OPERATION UNDER USUAL CONDITIONS
2-3. Preliminary Starting Procedure
dure must be performed with the data link
Before operation, set the data link control controls and
control POWER switch set to STBY. It should
uhf radio control controls as shown in table 2-3.
be noted that in STBY, only the encoder will
Table 2-3 Preliminary Control Settings
be tested during the AIRBORNE BITE test.
Component
Control
Setting
(2) After warmup of 3 minutes, set data link
Data link control
POWER
OFF
control POWER switch to XMT.
Uhf radio control
MANUAL/PRESET
MANUAL
(3) On data link control, depress the AIR-
Preset channel
Not operative
BORNE BITE switch. Observe that the BITE IN PRCS,
selector SWITCH
Manual frequency
Set to assigned
ENCODER FAULT and RT FAULT indicators come on for
frequency
3 seconds. This indicates successful lamp test
selector switches
(4) After the indicator lamp test sequence is
2-4. Initial Checks and Adjustments
completed, observe that the ENCODER FAULT and RT
WARNING
FAULT indicators go off and the BITE IN PRCS Indicator
Extreme danger from the aircraft propellers
remains on for an additional 3 seconds, after which it goes
exists when aircraft power is used to
off. This indicates that the AIRBORNE BITE test was
preflight the equipment. Use an auxiliary
successful. If reillumination of the ENCODER FAULT and/
power unit (APU) to provide equipment
or RT FAULT indicator occurs, the AIRBORNE BITE test
power whenever possible.
was not successful.
a. Visual Inspection.
NOTE
(1) Inspect equipment for cleanliness. Clean
Following initial observation of an ENCODER
as necessary with a clean cloth dampened with
FAULT or RT FAULT indication, recycle the
denatured alcohol or distilled water.
data link control POWER switch several
(2) Check all components for loose cable
times between XMT and OFF in an attempt to
connectors. (Refer to paragraph 3-10 for access hatch
clear the fault indication. Wait approximately
door opening and closing procedures.)
30 seconds between switch transitions
(3) Check to see that applicable aircraft circuit
NOTE
breakers are on (pushed in).
Disregard steps (5) and (6) when performing
(4) Check to see that mechanical action of
the AIRBORNE BITE test with the data link
each control listed in tables 2-1 and 2-2 is normal.
control POWER switch set to STBY.
b. Equipment Starting
(5) Set the uhf radio control MANUAL/PRESET
(1) Apply auxiliary power to aircraft and turn
switch to PRESET.
on inverter per applicable aircraft technical manual.
(6) Repeat steps (3) and (4) for each preset uhf
(2) Set data link control POWER switch to
receiver-transmitter channel, using the CHAN selector
STBY.
switch on the uhf radio control for channel selection.
c. Preflight Checkout Procedure.
NOTE
(1) Set uhf radio control manual frequency
If the preset channel frequencies have not
selector switches to assigned frequency.
been selected or if it is desired to change any
WARNING
one or all of the frequencies, follow the
When the data link control POWER switch
procedure given in steps (7) through (11)
is set to XMT, rf radiation through the
below. Otherwise, proceed to step (12).
(7) Set manual frequency selector switches to
is not given, the Preflight checkout proce-
2-3
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