a. Turn off power to the upconverter and turn on
and the LNA output levels of steps n through q above.
t. The gain should be within the limits of 39 + 2.0
power to the LNA. Allow one hour for warm-up.
b. Remove the screw fasteners on the front panel
dB. If such is the case, proceed to the overall receiver
of an upconverter drawer and pull the drawer forward on
u. Plot the power output reading vs. frequency on
c. Disconnect cable W5 going from the synthesizer
a graph. It is desireable to have a flat or slightly positive
slope of the LNA gain characteristic.
of the upconverter at J2 on module A4 and connect the
v. The LNA gain/slope may be adjusted by
same to the hard limiter test assembly (SM-A-934943)
removing the access covers and weatherproofing plugs
through the test cable assembly (SM-C-935488-1), and
on the side of the LNA as shown in figure C-2. A special
the SMA adapter provided in the test kit.
d. Remove the screw fasteners on the front panel
thin wall socket nut driver is required to loosen the
locknut on the screwdriver adjustment for the LNA pump
of the LNA control/translator drawer and pull the drawer
power and bias controls which affect the gain/slope of
forward on its slides.
e. Disconnect connector A2P53 going to recepticle
A CW rotation of the adjustment screw
produces a negative slope and vice versa; the
J8 (SHF OUT) at the rear of the LNA control/translator
adjustment sensitivity is approximately 5 dB/quarter turn.
drawer, and connect it to the output of the hard limiter
The bias control mainly affects the low frequency gain;
test assembly (SM-A-934943).
however both controls interact and therefore may require
f. At the AME assembly, disconnect the terminal
alternate repeated adjustments.
loop test cable (W15P2) from the bulkhead connector
w. If the gain of the LNA at the four frequencies is
and connect the cable to the RF power meter with low
not within + 2 dB of 39 dB adjust the bias control until
power head (HP-8484A) using a UG-29B/U adapter.
such is achieved. It also may be necessary to adjust the
g. Configure the shelter for normal operation and
pump control slightly.
To expedite the adjustment
turn the power ON except that the power amplifiers are
procedure, calculate and record the output level range
left on STBY.
limits in dBm for each frequency by adding 37 and 41 dB.
h. Tune the upconverter synthesizer test signal
For example an input level of 64 dBm will have an LNA
source to 8399.000 MHz and measure and record the
output range of 27 to 23 dBm.
x. The adjustment should be performed in
i. Repeat step h above at 8300.300 MHz.
accordance with conditions and procedures shown in
j. Repeat step h above at 8200.000 MHz.
k. Repeat step h above at 7950.000 MHz.
l. Disconnect the loop test cable from the RF
It may be necessary to perform the
power meter and connect same to the waveguide switch
adjustment procedures several times 'to
test input through the 14 dB and 6 dB series attbnuators
obtain the correct limits. It is better to
provided (SM-A-937237-1, and -3).
make several slight adjustments to the
m. Disconnect the output cable from the LNA to be
controls instead of attempting one large
tested and connect the HP-436A power meter with HP-
8484A power head using a UG-27D/U adapter to the
y. After the gain is correctly adjusted, lock the
LNA-1 or LNA-2 output port as the case may be, as
controls in accordance with the following:
selected at the LNA control/translator.
(1) Set the synthesizer at 8399 MHz and note
the reading on the power meter. This reading must be
With the test signal applied to the LNA
maintained when locking the controls.
test port of the W/G switch, the signal is
(2) Insert the screwdriver into the handle of
input to LNA-2 with selector switch on
the nut driver such that the screwdriver can be applied to
the LNA-1 on the LNA control/translator.
the pump power adjustment screw while the nut driver is
engaging the locknut.
n. Tune the synthesizer in the upconverter drawer
(3) While observing the power meter, gently
to 7950.000 MHz. Read and record the output level on
rock the adjustment screws back and forth very lightly
the HP-436A power meter.
and slowly tighten the locknut. Keep the gain at the
o. Repeat step n above at 8200.000 MHz.
desired level while performing this step.
p. Repeat step n above at 8300.000 MHz.
(4) After the locknut has been tightened,
q. Repeat step n above at 8399.00 MHz.
gently tap the adjustment screw with the tip of the
r. Calculate and record the LNA input level for
screwdriver to relieve internal stress in the locking
each frequency by decreasing the measured levels of
steps h through k above by 20 dB.
s. Calculate and record the LNA gain by taking the
algebraic difference between the levels of step r above