TM 11-5895-846.14
e. Measure the gain with the
(b)
Insert the screwdriver into the handle of
synthesizer set at 7950, 8200,
the nut driver such that the screwdriver can be applied to
8300 and 8399 MHz.
If
the pump power adjustment screw while the nut driver is
satisfactory, adjustment is
engaging the lock nut.
complete; if not satisfactory,
(c)
observe
conditions
and
While observing the power meter gently
compare with this table.
move the adjustment screws back and forth very
Proceed accordingly.
lightly and slowly tighten the lock nut. Keep the gain at
3.
a. Response has a
a. Set the synthesizer to
the desired level while performing this step.
negative tilt.
8399MHz.
(d)
After the lock nut has been tightened,
b. Adjust the gain by
b. Gain is low for all
rotating the pump
gently tap the adjustment screw with the tip of the screw
readings.
power control CCW to
driver to relieve internal stress in the locking mechanism.
reach the desired level.
(e)
Tighten the BIAS voltage control in a
c. Measure the gain with the
similar manner.
synthesizer set at 7950, 8200,
8300 and 8399 MHz.
If
(f)
Replace the weatherproof access caps,
satisfactory, adjustment is
remove all test cables and attenuators, restore all
complete; if not satisfactory,
drawers to normal and return the terminal to normal
observe
conditions
and
operation.
compare with this table.
Proceed accordingly.
Table 3-18. LNA Response Adjustment
4.
a. Response is relatively
a. Set the synthesizer to
flat
8399MHz.
Condition
Corrective Action
b. Reduce the gain by
1.
a. Gain relatively flat
a. Set the synthesizer to
slightly rotating the
for all
8399 MHz.
b. Gain is high at all
pump power control
frequencies.
frequencies.
CW until the correct
b. Gain below
b. Adjust the gain upward
level is reached.
minimum for
by rotating pump power
c. Set the synthesizer to
all frequencies
control slightly CCW
7950 MHz.
until the gain is within
d. Use the bias voltage
the required level (39 2
control to set the gain at
dB)
the same level
c. Set the synthesizer to 7950
measured in step b above.
MHz.
e. Repeat steps a and b
d. Using the BIAS voltage
above and adjust the
control adjust the gain up
gain to the same level
(CW) or down (CCW) to the
as first time.
same level as that in step b
f. Measure the gain with
above.
the synthesizer set at
e. Repeat steps a through d as
7950, 8200, 8300 and
necessary to obtain the
8399 MHz.
desired level.
If satisfactory, adjustment
f. Measure the gain with the
is complete; if not
synthesizer set at 7950, 8200,
satisfactory, observe
8300 and 8399 MHz.
If
conditions and compare
satisfactory, adjustment is
with this table. Proceed
complete; if not satisfactory,
accordingly.
observe
conditions
and
5.
a. Set the synthesizer to
compare with this table.
is within limits
8399MHz.
Proceed accordingly.
b. Adjust the pump power
2.
a. Set the synthesizer to
control in a CW direction
within limits. 8399 MHz.
is higher than limits
b. Slightly adjust the pump
to reduce the gain to
b. High frequency
power control CCW so
that measured for the
gain below limits.
that the gain equals that
low frequency
previously measured
(synthesizer at 7950 MHz)
with the synthesizer set
c. Measure the gain with
at 7950 MHz.
the synthesizer set at
c. Remeasure the gain
7950, 8200, 8300, and
with the synthesizer set
8399 MHz. If
at 7950 MHz; if
satisfactory, adjustment
necessary adjust the
is complete; if not
bias voltage and pump
satisfactory, observe
power controls to obtain
conditions and compare
the desired gain.
with this table. Proceed
d. Repeat steps a, b and c
accordingly.
as necessary.
3-36