TM11-5895-846-14
Table 5-10. Accessory Items Required for
(25) Restore the normal terminal cabling to the
Downconverter Receiver Gain Adjustment
unit front panel connectors. Return the special test
cables and devices to their respective stowage areas.
No
Item
Comments
(26) On the downconverter, remove the
1
Power Meter
HP 436A
terminal cable from the front panel SHF IN connector.
2
Adapter, UG-29
Type N adapter
(27) Connect the male end of the 4 dB test
3
Limiter Assy
P/n SM-A-934943
cable W403 to the downconverter SHF IN connector.
4
Test cable W401
P/n SM-C-935488-1
Connect the cable W404 to the loose end of cable W403
6 feet, low loss
and the downconverter TEST SIGNAL connector.
5
Test cable W403
P/n SM-C-935481-1
(28) Place the downconverter MONITOR
4 dB, 6 feet
switch to the TEST position and extend the unit from the
6
Adapter test cable P/n SM-C-935482-1
W404, 12 inches
locations. Place RCVR FAULT switch to 70.
7
Power Sensor
HP-8481A
(29) Observe the RCVR FAULT indicator. On
8
Power Sensor
HP-8484A
downconverter module A2, adjust control R3 (spectrum
9
Attenuator 6 dB
SM-A-937237-3
test) until the indicator just illuminates from an off
10
Adapter, BNC/N
UG-349 A/U
condition.
The MONITOR meter should indicate
11
Adapter, SMA
P/n SM-A-937679
approximately 15 units.
(female-to-female)
(30) Place RCVR FAULT switch in 700 position
and observe the RCVR FAULT indicator.
On
adjustment control locations. Observe the power meter.
downconverter module A3, adjust control R2 (spectrum
On downconverter module A2, adjust gain control R5
test) until the indicator just illuminates from an off
and R6 to obtain 10.6 dBm of output or 50 dB above
condition.
The MONITOR meter should indicate
level measured in step (12) above. The controls are
approximately 15 units.
interacting. It is suggested, therefore, that one control
(31) Disconnect the adapter test cable W404
(R5) be set to approximately midrange and the other
from the 4 dB test cable W403 and the TEST SIGNAL
(R6) adjusted to obtain the reference level. Try to keep
connector.
the settings away from the extreme ends of rotation.
(32) Connect the loose end of the 4 dB test
(19) Connect the HP 436A power meter with
cable W403 to the terminal SHF input cable.
the HP8481A power head to the 700 MHz IF output J3 of
(33) Place the downconverter MONITOR
downconverter.
switch to the IF OUT position and RCVR FAULT switch
(20) Read and record the 700 MHz output level
to 70.
of the downconverter. The output level now may or may
NOTE
not indicate the reference level of step (18) above.
The terminal antenna shall be pointed
Regardless of the indication, proceed to step (21) below
toward a quiet place in the sky during
and adjust the gain controls.
the next adjustment steps.
(21) See
downconverter
adjustment control locations. Observe the power meter.
(34) Observe the RCVR FAULT indicator.
On downconverter module A3, adjust gain controls R8
On downconverter module A2, adjust control R2
and R9 to obtain step (18) above level. The controls are
(operating noise) until the indicator just illuminates from
interacting. It is suggested, therefore, that one control
an off condition.
(R8) be set to approximately midrange and the other
(35) Place RCVR FAULT switch in 700 position
(R9) adjusted to obtain the reference level. Try to keep
and observe the RCVR FAULT indicator.
On
the settings away from the extreme ends of rotation.
downconverter module A3, adjust control R1 (operating
(22) Remove all special test cables and
noise) until the indicator just illuminates from an off
devices from the downconverter, upconverter, and LNA
condition.
control/translator. On the latter two units, restore the
(36) Disconnect the test cable from the
normal module and rear panel cable connections,
downconverter and the terminal SHF input cable. Return
respectively.
both test cables to their respective stowage areas.
(23) Close and secure all four of the above unit
(37) Close and secure the downconverter
drawers except do not secure the captive fasteners on
drawer. Connect the terminal SHF input cable to the
the downconverter.
front panel SHF IN connector. If necessary, dress and
(24) Check that the downconverter is tuned to
secure loose terminal cables in the rack cable troughs.
7500 MHz. (Refer to the above steps in this paragraph.)
5-50