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TM 11-5820-890-20-2
1-46
1.15.
REMOTE CONTROL UNIT (RCU), C 11561(C)/U. Continued
c.
Self Test. The C 11561(C)/U (RCU) self test is selected by setting the FCTN switch to the TST position.
The COMSEC switch must be set to CT before the self test can be run, if not the RCU will display FAIL 9
or GO PT. The displays and audio should be as shown below.
B
E
E
P
HI
LO
QUIET
LED DISPLAY
10
2
0
AUDIO
BLANK
QUIET
NUMERICAL
SECTION
SIG
SEGMENTS
BLANK
QUIET
TWO TONE
ALARM
12
20
28
HI
LO
HI
LO
HI
LO
HI
LO
The display is the first section tested in self test. The first display is • C". The letter •C" shows that the
COMSEC module in the RCU is present. If this module is absent, its letter in the display is replaced by a
dash ( ). The next display checks the display elements. All the dots in each digit of the display are lit.
The RCV SIG display segments are lit in sequence. The HUB display is also lit.
After the display is checked, the RCU continues its internal self test. If there are failures in the RCU, a
•FAIL 9" will appear on the display. After successful completion of the RCU internal self test, the RT
self test is initiated. The RCU displays the RT self test as described in section NO TAG RT 1523(C)/U
SELF TEST. If no failures occur in the RCU or it's companion RT, testing will terminate with a •GOOD"
display.
d.
Clearing Memory. When the RCU FCTN switch is set to Z FH, all preset frequencies and frequency
hopping data stored in the RT are cleared from memory. RCU COMSEC memory is cleared by setting
the COMSEC switch to Z. The COMSEC switch must be set to Z for 10 seconds in order to clear the
KEK loaded in CHAN position 6. All RCU memory is cleared each time the RCU FCTN switch is set to
OFF. Use the STBY position to retain information stored in memory.
e.
Additional Tests.
The RCU display will read •OPEN" if the RT FCTN switch is not placed in REM, field wire is disconnected
or open, or one of the system units has an open in the two wire path.
RF energy reflected back into the RT is measured by a VSWR detector and compared to the forward
power. When the VSWR goes above the 5 to 1 ratio, the sidetone is turned off at the RT. If this situation
arises the RT sends a control word to disable sidetone at the RCU.
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