5-30 888-2595-001 12/20/11
WARNING: Disconnect primary power prior to servicing.
Section 5 Maintenance and Alignments
ZX Series
chassis reading may increase, while others decrease, but total level
remains roughly constant. If both reverse power levels increase
dramatically, PA imbalance should be suspected. Perform these checks:
a.Verify both PA chassis have similar PA AMPS readings to within +/- 10
A.
b.Verify drive cables to PA chassis have not been replaced with an
incorrect length cable.
STEP 9 Switch transmitter off and reconnect load input cable.
STEP 10 Procedure complete
5.5 Special Part Replacement Notes
This section contains a collection of notes addressing certain aspects of the replacement
of major ZX subassemblies. For additional information consult Section 1 - Introduction
for aid in identifying the major subassemblies.
5.5.1 PA Module (992-9992-041G or otherwise)
• See PA module swap procedure earlier in this section.
• Verify that P/N of new module matches old module.
• Do not mix different P/N modules within same transmitter.
• No user adjustments.
• Modules are hot-pluggable; they can be removed and replaced while
transmitter is in operation.
• Modules are symmetrical; they can be inserted into transmitter with either
side facing up (they cannot be inserted wrong).
5.5.2 PA Amplifier Assembly (PWA, PA) (992-9992-021G
or otherwise)
In the event of an RF power MOSFET failure, field replacement of a single transistor is
not practical due to the cost of components, time, and test equipment involved in repair
and alignment of phase, gain, and response. This is a highly critical area, and if not
done correctly, improper module and transmitter operation will occur. Instead, a single
amplifier board (1/2 of module) may be replaced by following the procedure given
below. The piece to be replaced is illustrated by item [003] in Figure 5-3 below.
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