Return the cable to the proper channel. No action
required at the amplifier/mixer. If the indication is correct
After replacement of module A1, A2,
when the cable is connected to a different channel or to
power amplifier, the problem is in the SHF combiner
and perform the gain adjustment
module. Replace the SHF combiner module Al (para 5-
steps associated with the replaced
36 and perform the gain adjustments.
(10) On the amplifier mixer, place the STATUS
(12) Place the SHF MONITOR channel
MONITOR switch to the following positions and observe
selector switch to the SHF OUT position.
the STATUS MONITOR meter for a correct indication. If
(13) Observe the SHF MONITOR meter for a
an indication cannot be read in any position proceed to
reading of 14 to 18. If the indication is incorrect, the
step (11) below. If an indication cannot be read in the
operator may adjust A2AT1 to obtain the correct reading.
IPA MA position only, proceed to step (12) below. If all
If the correct reading cannot be obtained by adjusting
indications are normal, proceed to step (13) below.
A2AT1, perform steps b(l) through b(9) below.
b. Troubleshooting the Amplifier/Mixer.
+ 30 V
(1) If the indication in step a(13) above is not
+ 15 V
correct but the FAULT lamp is not illuminated proceed to
- 15 V
step (2) below to correct the SHF output fault, and then
attempt to adjust the fault threshold in accordance with
(11) Disconnect the leads from the rear of the
STATUS MONITOR meter. Set the multimeter to the
and then repeat the adjustment.
200 ohm range. Observe polarity and connect the
(2) If the fault still exists, replace A3 module
and observe for deflection on the STATUS MONITOR
36), and return to step a(1l) above.
meter. If there is no deflection, replace the STATUS
(3) If the indication in step a(13) above is
MONITOR meter. If there is deflection replace the
incorrect and the fault indication is illuminated, turn off
amplifier/mixer drawer and refer it to the next higher level
POWER switch and disconnect all drive cables to the
of maintenance. Return to step a(l) above.
inputs of the SHF channel combiner.
(12) Replace the transient suppressor module
(4) Turn off drawer. Disconnect output cable
A4. Return to step a(1) above.
W6 from the FET/TWT amplifier, select one of the input
(13) On the amplifier/mixer, place the SHF
cables to the amplifier/mixer drawer, and connect this
MONITOR switch to the X10 position and set the SHF
cable (via the appropriate adapter) to output cable W6.
MONITOR channel selector to each of its positions while
Terminate the TWT amplifier with a 50-ohm load. Turn
observing for an indication. Each (channel) position that
on POWER switch.
has an upconverter input applied as well as the SHF
(5) If the SHF MONITOR meter now indicates
OUT position, should give an indication on the SHF
power is present at the SHF output position,
MONITOR meter. If no readings can be obtained,
(approximately 5 to 10), the problem is most likely in the
proceed to step (14) below. If readings can be obtained
A2 module or A3 module.
only in certain individual positions of the SHF MONITOR
(6) Replace module A3, perform the gain
channel selector replace the amplifier/mixer drawer and
return it to the next higher level of maintenance. If all
(7) If fault remains, replace module A2 and
indications can be read, proceed to step (16) below.
(14) Replace the power head A7 in the
amplifier/mixer and observe for indications on the SHF
(8) If fault still remains, replace the
MONITOR meter. If indications return, return to step
a(1) above. If indications still cannot be read, proceed to
step (15) below.
(9) If no output power is indicated in the SHF
(15) Disconnect the leads from the rear of the
output position of the SHF MONITOR meter, replace
module A6. Perform the gain adjustment steps in
ohm range. Observe polarity and connect the multimeter
to the SHF MONITOR meter terminals and observe for
deflection on the SHF MONITOR meter. If there is no
deflection, replace the SHF MONITOR meter.