Nautel XR12, Troubleshooting Manual, Page: 68 / 283

XR12 Troubleshooting Manual Responding to alarms
Page 1-48 Issue 3.0 2009-07-28
RF amplifier assembly replacement
1. Remove the RF amplifier assembly from RF power module. Use the hex screw driver
(Nautel part # HAZ65) from the ancillary kit to remove the RF amplifier assembly’s
attaching hardware (four M3 hex head screws) at the rear of the RF power module's heat
sink.
2. Discard or repair the defective RF amplifier assembly.
3. Apply a thin film of thermal compound to the RF amplifier assembly’s aluminum heatsink
plate.
4. Install the replacement RF amplifier assembly in the RF power module. Mate the RF
amplifier assembly's connector J1 to the PA input/output PWB's connector in the RF power
module.
5. Secure the RF amplifier assembly to the RF power module's heatsink using the four M3 hex
head screws removed in Step 1 .
CAUTION:
The heat sinks of modulator assemblies and RF amplifiers are coated with a film
of thermal compound. Use care to ensure the film does not become contaminated
with foreign particles.
When installing an assembly, visually inspect the mating surfaces of its heat sink
and the module's chassis. Ensure both surfaces are coated with a thin film of
thermal compound. Ensure foreign particles that may affect thermal transfer are
not embedded in the compound.