TM 11-5895-846-14
(1) In the PA, place the REFL WATTS/FWS
f).
WATTS switch to the FWD WATTS position and the
MONITOR switch to the appropriate range position and
f.
HV ARC and BODY OVLD Fault and HV
record the output power as indicated on the MONITOR
INHIBIT Status Indicators. In addition to the indicators,
meter.
the HV MAIN fuse may have blown and its indicator will
(2) Place the REFL WATTS/FWD WATTS
be illuminated.
switch to the REFL WATTS (hold) position and record
(1) On the power supply place the
the reflected power as indicated on the MONITOR meter.
OPERATE-STANDBY switch to the STANDBY position.
(3) If the power recorded in step (2) above is
(2) Place the FAULT CKT/RESET switch to
over 10% of that recorded in step (1) above the problem
the RESET position and then release it.
is in the waveguide and connections between the SHF
(3) If necessary, replace the HV MAIN fuse.
(4) Place the power supply OPERATE-
NOTE
STANDBY switch to the STANDBY position.
A spare fuse is located in the SPARE
(5) Carefully examine the waveguide, the
holder to the left of the HV MAIN fuse.
connections and the feedhorn for damage. Remove and
(4) Place the OPERATE-STANDBY switch to
replace damaged items, as necessary.
the OPERATE position.
(6) If the power recorded in step (2) above is
(5) If all fault lamps are extinguished after
not over 10 % of that recorded in step (1) above and the
step (3) above the failure was a random are and no
fault lamps are still illuminated, position the transmit
further action is required.
waveguide switch so this PA is connected to the dummy
NOTE
load (not on-line).
If a high voltage arc occurs at turn-on
(7) Again measure the power as in step (1)
(STANDBY to OPERATE), the HV ARC
and (2) above.
indicator will not illuminate but the
(8) If the reflected power is more than 10% of
BODY OVLD indicator will illuminate
the forward power, the problem is in the waveguide
and the HV MAIN fuse will blow.
between the SHF OUT flange and the dummy load.
(6) If the fault lamps remain illuminated after
Carefully examine the waveguide for damage and
step (4) above, remove the primary power from the
remove and replace, as necessary.
power supply by placing the associated PA/AUX circuit
(9) If the reflected power is less than 10% of
breaker to the OFF position on the power distribution
forward power and the fault lamps are still illuminated,
panel. The AC POWER indicator on the power supply
the problem is in the internal waveguide; return the PA to
must be off.
the next higher level of maintenance.
(7) Loosen the eight captive screws on the
e. BODY OVLD Fault and HV INHIBIT Status
power supply front panel.
Indicators.
(8) Pull on the two handles to extend the
(1) On the power supply place the MONITOR
power supply from the rack.
switch to the BODY MA X5 position.
(9) Disconnect the cable from connector J3
(2) On the power amplifier (PA) reduce the
on the rear panel of the unit.
RF drive to the klystron by turning the OUTPUT LEVEL
(10) Place the OPERATE-STANDBY switch in
control several turns counterclockwise.
the STANDBY position.
(3) On the power supply place the
(11) If necessary, replace the HV MAIN fuse.
OPERATE-STANDBY switch to the STANDBY position.
(12) Remove fuses HV1 and HV2.
(4) Place the FAULT CKT/RESET switch to
(13) On the power distribution panel place the
the RESET position and then release it.
associated PA/AUX circuit breaker to the ON position.
(5) Place the OPERATE-STANDBY switch to
(14) Wait approximately 5 minutes until the FIL
the OPERATE position and observe the MONITOR
INHIBIT indicator turns off and then place the
meter on the power supply.
OPERATE-STANDBY switch to the OPERATE position.
(6) If the fault indicators are extinguished and
(15) If the BODY OVLD and HV INHIBIT
the MONITOR meter indicates less than 10 ma, the fault
indicators are still illuminated, the problem is in the power
was only a momentary one.
supply. Remove the unit (para 5-21) and return it to the
(7) If the fault indicators remain illuminated
next higher level of maintenance.
and the MONITOR meter fluctuates, the problem' is in
NOTE
The HV MAIN fuse indicator may also
be illuminated if the fuse has blown.
5-13