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WARNING: Disconnect and lockout AC primary power prior to servicing
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7.7.7 RF Trouble Shooting Divider and Combiner
7.7.7.1 Power Divider
The output power of any divider can be verified by power measurement. An analog
average power meter can be used to compare outputs but does not accurately measure
the power.
7.7.7.2 Combiner
High Output VSWR Fault (1 blink) The cause for this fault is often external to the
module. First, check the system VSWR on the display panel, and check for a VSWR
foldback or VSWR overload condition on the transmitter. Check the other modules in
the same cabinet for VSWR faults as well. If either is found, suspect a problem in the
system outside the cabinets.
If not, then the problem is either in the suspect module or its cabinet. The swap test is
the easiest way to isolate the problem. Swap the VSWR faulting module with a properly
working one from another slot. If the problem remains in the same slot, check the RF
output cable, connector, and 50 ohm combiner reject load for that module slot. Inspect
the RF cables for poor shield crimp. Disconnect each end of the cable and inspect for
center pin heating. Verify that the center pins concentric and have not pulled back from
the end. Any part of one Gysel network loop may be interchanged with a similar section
of another loop. The part numbers of the cable is stamped on shrink tubing at each end
of the cable.
If the problem follows the module, use the information in the RF module section to
troubleshoot. The location of the directional coupler is just before the output connector,
the only true VSWR in the module would be a bad connection between the directional
coupler and the output connector.