Harris Platinum Z2 CD, Manual

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3-10 888-2406-002
WARNING: Disconnect primary power prior to servicing.
Operator Guide
3.5 Emergency Operating Procedures
!
WARNING:
THE PA MODULES ARE DESIGNED TO HANDLE VERY HIGH TEMPERATURES
AND MAY BE EXTREMELY HOT. DO NOT TOUCH THE MODULES WITH BARE
HANDS AFTER THE TRANSMITTER HAS BEEN RUNNING, ESPECIALLY IN HIGH
AMBIENT TEMPERATURE ENVIRONMENTS.
3.5.1 Multiple PA Failures in a Foursome
If two PAs were to fail in a single group of four or Foursome, the resulting system
imbalance would result in a power foldback to approximately 50% of nominal
power output. Since a single PA failure in a foursome does not create an imbalance
severe enough to cause foldback, one of the PA modules with a bad PA should be
taken out and swapped for one of the modules on the opposite side of the
transmitter, placing the PA in a different foursome. For example, if PA amplifiers
B1 and B2 have failed (these are in the front of the transmitter), pull out the B2 PA
module, and swap it with any of the PA modules in the rear of the transmitter such
as B5. There are still 2 failed PAs, B1 and B5, but now each one is in a different
foursome. This will restore balance to the system and the transmitter will still be
able to operate at near full power output by automatically increasing the drive to the
remaining PAs (via the APC voltage).
For more information on Foursomes refer to Section IV, Overall System Theory,
under the heading “8-Way Combiner”.For quick reference, the foursome groupings
are as follows:
(See Figure 4-5 and Figure 4-5 on page 4-11, in Section IV)
•
B1, B2, B3 and B4 - Front Foursome
•
B5, B6, B7 and B8 - Rear Foursome