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WARNING: Disconnect primary power prior to servicing.
Maintenance and Alignment
5.4 Routine Annual Tests
These tests should be used as part of a routine maintenance program at least once a
year. It should also be done if major combiner components are removed and/or
replaced, such as a Z-Plane or Isolation Board or if cabling is disconnected and re-
connected to the Z-Planes or Isolation Boards.
5.4.1 System Level ISO/Reject Load Ohmmeter Test
The ISO/Reject loads for the Z-Plane can be physically tested using an ohmmeter.
Shut off the transmitter and disconnect primary power at the wall breaker. Remove a
PA module to allow access to the Z-Plane connectors. Connect the common lead of
the meter to the chassis and check pins 14 or 15 on the Z-Plane connector. The
resistance should be 50 ohms +/- 3 ohms for Z-Plane B. This is checking ISO_AB,
the 50 ohm reject load on the 3dB hybrid which is combining the 2 Z-Plane outputs.
Z-Plane A will read a short due to the static discharge choke L1 at the bottom of the
harmonic filter. Figure 5-1 shows the connector numbering and lettering for the Z-
Plane connectors. This diagram will work when looking at the front or back of the
transmitter on any power block, or PA slot.
Figure 5-1 Z-Plane Connector Pinouts for any PA Module
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