TM 11-5895-846-14
(5) Tighten the bias voltages control in a
similar manner.
(6) Replace the weatherproof
access
caps, remove all test cables and attenuators, restore all
drawers to normal and return the terminal to normal
operation.
Table C-1 LNA Response Adjustment
Condition
Corrective Action
1. a.
a.
Gain relatively flat
Set the synthesizer to 8399 HMz.
b.
Adjust the gain upward by rotating power pump control slightly CCW until
for all frequencies
b.
Gain below minimum
the gain is within the required level (39 + 2 d B)
c.
Set the synthesizer to 7950 MHz.
for all frequencies
d.
Using the bias voltage control adjust the gain up (CW) or down (CCW) to the same
level as that in step b above.
e.
Repeat steps a and b above as necessary to obtain the desired level.
f.
Measure the gain with the synthesizer set at 7950, 8200, 8300 and 8399 MHz.
If satisfactory, adjustment is complete; if not satisfactory, observe conditions
and compare with this table. Proceed accordingly.
2. a.
a.
Low frequency gain
Set the synthesizer to 8399 MHz.
b.
Slightly adjust the pump power control CCW so that the gain equals that
within limits
b.
High frequency
previously measured with the synthesizer set at 7950 MHz.
c.
Remeasure the gain with the synthesizer set at 7950 MHz; if necessary adjust the
gain below limits
bias voltage and pump power controls to obtain the desired gain.
d.
Repeat steps a, b and c above as necessary.
e.
Measure the gain with the synthesizer set at 7950, 8200, 8300 and 83 99 MHz. If
satisfactory, adjustment is complete; if not satisfactory, observe conditions and
compare with this table. Proceed accordingly.
3. a.
a.
Response has a negative
Set the synthesizer to 8399 MHz.
b.
Adjust the gain by rotating the pump power control CCW to reach the
tilt
b.
Gain is low for all
desired level.
readings.
c.
Measure the gain with the synthesizer set at 7950, 8200, 8300 and 8399 MHz.
If satisfactory, adjustment is complete; if not satisfactory, observe c onditions
and compare with this table. Proceed accordingly.
4. a.
a.
Response is relatively
Set the synthesizer to 8399 MHz.
b.
Reduce the gain by slightly rotating the power pump control CW until the
flat
b.
Gain is high at all
correct level is reached.
c.
Set the synthesizer to 7950 MHz.
frequencies
d.
Use the bias voltage control to set the gain at the same level
measured in step b above.
e.
Repeat steps a and b above and adjust the gain to the same level as first time.
f.
Measure the gain with the synthesizer set at 7950, 8200, 8300 and 8399 MHz. If
satisfactory, adjustment is complete; if not satisfactory, observe conditions
and compare with this table. Proceed accordingly.
5. a.
a.
Low frequency gain
Set the synthesizer to 8399 MHz.
b.
Adjust the pump power control in a CW direction to reduce the gain to that
is within limits
b.
High frequency gain
measured for the low frequency (synthesizer set at 7950 MHz)
c.
Measure the gain with the synthesizer set at 7950, 8200, 8300 and 8399 MHz.
is higher than
limits
If satisfactory, adjustment is complete; if not satisfactory, observe conditions
and compare with this table. Proceed accordingly.
6. a.
a.
Response has a
Set the synthesizer at 8399 MHz.
b.
Adjust the pump power control in a CW direction to decrease the gain to the
positive tilt
b.
Gain is higher at
desired level.
c.
Set the synthesizer at 7950 MHz and adjust pump power and bias voltage
all frequencies
controls to obtain the same gain as obtained in step b above.
d.
Measure the gain with the synthesizer set at 7950, 8200, 8300 and 8399 MHz.
If satisfactory, adjustment is complete; if not satisfactory, observe the conditions
and compare with this table. Proceed accordingly.
C-4
