(1) Remove the feed-tube from the antenna
(17) Repeat the
above steps for other
center section and replace it with a dust cap or aim the
downconverters as required.
antenna at a quiet spot in the sky.
(18) Replace the antenna feed, remove all test
(2) Loosen the captive screws on the front
cables, and restore all normal connections on the
panel of the upconverter drawer and pull the drawer
drawers to return the shelter to normal operation.
forward on its slides.
(3) Disconnect cable W5 going from the
Performing the Transmit-Receive System
synthesizer of the up converters at J2 on module A4 and
connect the same to the hard limiter test assembly (SM-
Accomplishment of this procedure will check the
A-934943) through the test cable assembly (SMC-
continuity and/or performance of the transmit-receive
935488-1) and the SMA adapter provided.
loop through the following on-line units or functions;
(4) Loosen the captive screws on the front
transmit side of transmit-receive modem, upconverter,
panel of the LNA control/translator drawer and pull the
power amplifier (and associated power supply), antenna
drawer forward on its slides.
receiver directional coupler, LNA waveguide switch,
(5) Disconnect the connector A2P53 going to
selected on-line LNA, LNA BITE unit coaxial transfer
receptacle J8 (SHF OUT) at the rear of the LNA
switch, SHF IN cable, receiver power splitter
control/translator drawer and connect it through a 6dB
(downconverter input patch), the downconverter
attenuator to the output of the hard limiter test assembly,
associated with the transmit-receive modem and the
receive side of the transmit-receive modem. Check that
(6) Configure the shelter for normal operation
AC power is applied to all units. The transmitter will drive
and turn the power ON. The power amplifiers are left on
into the dummy load and not transmit to the satellite.
The transmitter group 1 is assumed to be online along
(7) At the antenna mounted assembly,
with transmit-receive modem 1 and associated
disconnect the terminal loop test cable from the LOOP
TEST coupler and connect the cable to the RF power
a. On the alarm monitor, place the AUDIBLE
meter with low power head HP-8484A using a UG-29B/U
SIGNAL/FAULT switch to the OFF position.
b. On the downconverter, place the FREQ
(8) Set the upconverter synthesizer to 8399
SELECT MHz switches to that receive frequency which
MHz and the downconverter to 7699.000 MHz and
is 725 MHz below the on-line upconverter transmit
measure and record the signal level.
frequency (refer to para 3-11 for receiver tuning
(9) Repeat step 8 above at 8200 MHz and
procedure). This frequency setting is temporary only and
in support of this translator loop test and the satellite
(10) Repeat step 8 above at 7950 MHz and
c. On the power distribution panel check that the
(11) Disconnect the loop test cable from the
PA/AIR COND switch is in the (on-line) PA1/AIR
power meter and connect it through the 14 dB attenuator
COND2, PA2/AIR COND2 position. Restart the air
to the LOOP TEST coupler.
conditioner, if necessary.
(12) Calculate and record the input levels for
d. Position the transmit waveguide switch so that
each frequency by subtracting 14 dB from the measured
levels of steps 8, 9 and 10 above.
dummy load (PA2 is set to on-line).
(13) Connect the power meter with the
e. On the PA1 power supply, place the
HP8481A head to the 70 MHz OUTPUT (4) of the
OPERATESTANDBY switch to the OPERATE position.
downconverter to be measured.
J. On the antenna control, place the MODE
(14) Read and record the measured level. The
switch to the MANUAL position and the MONITOR
level should be at least 50 dB above the level calculated
switch to the CARRIER LEVEL position.
in step 12 above.
g. On the LNA control/translator, place the
(15) The output level may be adjusted if
TRANSLATOR switch to the ON position. Observe that
necessary at the 700/70 MHz mixer assembly A2A1 in
the TRANSLATOR indicator is illuminated.
the downconverter drawer, with the receiver gain
h. On the antenna control, set the MGC control to
adjustment control R5 or MDL gain control R6.
the 130 position.
(16) The overall receiver gain may be
On the selected transmit-receive modem, open
measured for receive frequencies of 7250 MHz and 7699
the unit (approx. two inches) and place the XMT and
MHz by tuning the upconverter synthesizer to 7950 MHz
RCVR function switches as follows:
and 8399 MHz respectively. Output levels should be at
(1) Switch S13 to the center position.
least 50 dB above the input at the 20 dB coupler.
(2) Switch S14 to the NORMAL position.