TM11-5895-846-14
Light shall illuminate when pressed in. Note that all BITE
(20) If either or both indications are incorrect,
lights are operated from a + 24 Vdc PS1 line.
remove and replace the downconverter module A2 (para
(10) Fine tune the FREQ TUNE control to
obtain a midscale indication on the MONITOR meter.
and perform the gain adjustment.
(11) If midscale indication cannot be obtained,
(21) Remove the low-loss jumper cable from
proceed to step (14) below.
the front panel connector and replace the SHF cable
(12) Place SYNTH MON switch to each of the
before performing the gain adjustment.
b. Testing the Frequency Synthesizer Module.
following positions and observe MONITOR meter for a
correct indication.
Position
Indication (Meter Units)
testing of the frequency synthesizer module.
∅ Err
5-30. Downconverter, Receiver Gain Adjustment
15-35
NOTE
SHF LO
15-35
The receiver gain is calibrated using
630 MHz
15-35
SP Gen
15-45
signal sources within the terminal in
1 MHz
15-42
conjunction
with
precision
1 kHz
15-35
attenuators and a low level SHF hard
125 kHz
15-35
10 kHz
15-35
signal at the local receiver frequency
Freq. Std
15-35
is obtained from the SHF local
IF
10-45
(13) If any indication in step (12) above is
synthesizer in the upconverter
incorrect, proceed to step (14) below. If all indications
drawer.
The output level of this
are correct, proceed to step (15) below.
signal is between the limits of + 6 and
(14) Test the frequency synthesizer module A1.
+ 12 dBm and is passed through the
SHF hard limiter and attenuator to
testing of the frequency synthesizer module.
provide a -52 dBm signal at the 20 dB
(15) Remove the SHF cable from the SHF IN
coupler on the AME subassembly,
connector and connect low-loss (SM-C-937321) cable
which gives a nominal -72 dBm signal
between SHF IN and TEST SIGNAL connectors.
at the LNA input.
(1) Remove the feed-tube from the antenna
SELECT MHz and FREQ TUNE controls to a frequency
center section and replace it with a dust cap or aim the
within +20 MHz (IF passband) of 7500 MHz.
antenna at a quiet spot in the sky.
(17) Place the RCVR FAULT switch in 700
(2) Loosen the screw fasteners on the front
position and place the MONITOR switch to the TEST
panel of the upconverter drawer and pull the drawer
position. Observe that the MONITOR meter indicates
forward on its slides.
greater than 17 and the RCVR FAULT indicator is
(3) Disconnect cable W5 going to J2 of the
extinguished.
upconverter A4 module and connect the input of the hard
(18) If either or both indications are incorrect,
limiter test assembly (SM-A-934943) through test cable
remove and replace the downconverter module A3 (para
assembly (SM-C-935488-1) and the SMA adapter
provided in the test kit.
and perform the gain adjustment. Proceed to step (19)
(4) Loossen the screw fasteners on the front
below if indication is normal.
panel of the LNA control/translator drawer, and pull the
NOTE
drawer forward on its slides.
A3 module provides SHF MX/IF
(5) Disconnect the connector A2P53 going to
preamp sections also for the 70 MHz
receptacle J8 (SHF OUT) at the rear of the LNA
channel. If these sections develop
control/translator drawer and connect it to the output of
faults, both A3 and A3 BITE
the hard limiter test assembly, SM-A-934943.
indicators
will
show
incorrect
(6) At the antenna mounted assembly,
readings. Only A3 module has to be
disconnect the terminal loop test cable from the LOOP
investigated further, however.
TEST coupler and connect the cable to the RF power
(19) Place the RCVR FAULT switch in 70
meter and low power head HP-8484A using a UG-29B/U
position and place the MONITOR switch to the TEST
adapter.
position. Observe that the MONITOR meter indicates
(7) Configure the shelter for normal operation
greater than 17 and the RCVR FAULT indicator is
and turn the power ON.
extinguished.
5-47