TM11-5895-846-14
(6) If the indication is correct, proceed to step
5-24. Upconverter Gain Adjustments
(7) below. If the indication of step (5) above is not
The gain of the upconverter must be adjusted upon
correct, the problem is in the frequency standard;
replacement of the 70/700 MHz upconverter module A2,
remove and replace the standard Y1 (refer to para 5-
the 700 SHF mixer module A4, or the SHF filter/detector
26d). If indication is still incorrect, replace synthesizer.
module A5.
This is necessary to accommodate
(7) Rotate the SYNTH MONITOR switch to
individual gain variations. It is assumed here that a
630 position and observe for an indication between 15
module has just been replaced, the front panel cables
and 35 on the meter. Rotate the switch to SP GEN
are disconnected, the upconverter is extended from the
position and verify an indication between 12 and 38.
rack, and the AC power is turned off. Proceed as
(8) If indications are correct, proceed to step
follows:
(10) below. If one or both indications in step (7) above
NOTE
Refer to table 5-9 for accessory items
defective; proceed to step (9) below.
required to perform the gain
(9) Remove and replace the fixed frequency
adjustment procedure. Unless noted
generator module Al (refer to para 5-26a).
otherwise, these items are stowed in
(10) Rotate the SYNTH MONITOR switch to
the shelter in an auxiliary test items
the 1MHz position and observe for an indication between
bag.
Refer to table 2-1 for the
15 and 42 on the MONITOR meter.
stowage location.
(11) If the indication in step (10) above is not
correct and/or the FAULT 1 MHz LOOP lamp is
a. Initial Condition.
illuminated, the problem is in the one MHz step module
(1) Close the upconverter drawers and
A2; remove and replace it (refer to para 5-26e). If the
partially tighten one of the front panel captive screws.
indication is correct, proceed to step (12) below.
(2) Place the front panel POWER circuit
(12) Rotate the SYNTH MONITOR switch to
breaker to the ON position and tune the upconverter to a
the 1 kHz position and observe for an indication between
midband frequency between 8100 and 8200 MHz (para
15 and 35 on the MONITOR meter.
(13) If the indication is correct, proceed to step
b. System Using 700. MHz Modem and 70 MHz
(14) below. If the indication is not correct and/or the
Modem.
FAULT 1 kHz LOOP lamp is illuminated, the problem is
(1) On the rack cable through to the left side
in 1 kHz STEP module A3; remove and replace it (refer
of the upconverter, loosen the captive screws and open
to para 5-26e).
all the cable access covers.
(14) Rotate the SYNTH MONITOR switch to
(2) Free the modem 700 MHz drive cable
the 125 kHz position and observe an indication between
from the cable trough. Also free the SHF cable up to the
15 and 35.
amplifier/mixer. Do not remove this cable from the
(15) If the indication is correct, proceed to step
amplifier/mixer.
(16) below. If indication is not correct remove and
(3) Connect the amplifier/mixer cable to the
replace 1 MHz step module A2.
front panel SHF OUT connector on the upconverter.
(16) Rotate the SYNTH MONITOR switch to
(4) At the IF patch panel, remove one of the
the 10 kHz position and observe an indication between
c/kt test cables from its c/kt attenuator connector. If
15 and 35.
necessary, open the appropriate cable trough access
(17) If the indication is correct, proceed to step
cover to free the cable.
(18) below. If indication is not correct remove and
(5) Connect one end of the c/kt test cable to
replace the 1 kHz step module A3.
the upconverter 700 MHz IF IN connector. Turn IF IN
(18) With the OUT OF LOCK lamp illuminated,
switch to 700 MHz position.
(indicating the synthesizer cannot be locked by fine
tuning FREQ TUNE) rotate the SYNTH MONITOR
Table 5-9. Accessory Items Required for Upconverter
switch to the IF position and observe an indication above
Gain Adjustments
15.
No Item
Comments
(19) If indication is not correct, remove and
1
Step attenuator 1-12 dB
P/N SM-A-939970
replace YIG Filter module FLI. (refer to para 5-29c).
2
c/kt cable, low loss, 3'
P/N SM-C-775834-19
(20) If indication is correct or if step (19) above
P/O IF patch panel
did not fix the problem, remove main loop module A4
(refer to para 5-27b).
(21) If the unit still will not lock-up, problem is n the
switch assembly. Return the frequency synthesizer to
the next higher level of maintenance.
5-39
