Nautel VX150, Manual

Page: 27 / 105

VX150 TO VX2 TROUBLESHOOTING MANUAL RESPONDING TO ALARMS
VERSION 0.1 2020-12-01 PAGE 3.1.19
Power Amplifier PWB Replacement
See Figure 3.1.5 on page 3.1.21 of this section, and MD-1 and MD-9 in the Mechanical Drawings
section of this manual.
1. Turn RF off and disconnect the ac power from the transmitter.
2. Before replacing a suspect Power Amplifier PWB, verify the fault is with the suspect Power
Amplifier PWB by performing the continuity and resistance checks detailed in
“PA Resistance
Checks” on page 3.1.22 . If you are prompted to replace a Power Amplifier PWB, return to Step 3 of
this procedure.
3. Remove the MCX RF drive connector from J1 on the Power Amplifier PWB.
4. Remove and retain the M3 screw securing the PA volts at E1.
5. Remove and retain the M3 screw securing the jumper connecting the Power Amplifier PWB to the
Low Pass Filter at E2.
6. Remove and retain the two M3 screws securing the FET on Power Amplifier PWB.
7. Remove and retain the four M3 screws securing the Low Pass Filter cover. Remove the cover to
access the jumper described in
Step 5 . Loosen the M3 screw and move the jumper off to the side to
allow the Power Amplifier to be removed.
8. Remove and retain the eleven M2.5 screws securing the Power Amplifier PWB to the heat sink.
9. Remove the Power Amplifier PWB.
10. Obtain the replacement PA Replacement kit (Nautel part # 235-5046) from the Station Spare kit
(Nautel part # 235-5043).
11. Obtain the new NAPA40 PA, thermal pad (Nautel part # HAK77C) and thermal compound (Nautel
part # HAG80) that is supplied with the PA Replacement kit. Spread a small amount of thermal
compound thinly and evenly on the pad.
NOTE
: FETs are static sensitive and must be handled in a static protected manner.
CAUTION! The thermal compound is electrically conductive, so care must be take
to ensure it is only on the thermal pad.
CAUTION! When installing FET securing hardware, you can damage the FET case if
you fully tighten one screw while the other is loose. Avoid this by alternately
tightening the two screws.