4-52
888-2586-001
9/15/06
WARNING: Disconnect primary power prior to servicing.
Platinum Z16HD+
Section 4 Overall System Theory
Whenever a defective PA is to be shut off or MUTED, all of the PAs will be MUTED
for 120mS while the defective PA is disconnected from the combiner by the isolation
switch. The rest of the PAs are then turned back on.
4.8.5.2
Control Distribution and Controller Failure
Each PA Controller controls (8) of the PAs on either Z-Planes A and B or Z-Planes C
and D, see table 4-1. Note that each PA Controller Board controls two PAs on each
foursome. This pattern of control distribution allows for maximizing of power output if
one of the PA Controller Boards fails. Keep in mind, that if a PA Controller fails,
another PA Controller will detect this, MUTE the system, and switch the isolation
relays associated with the PAs controlled by the failed PA Controller Board. This is
called a “Crossover”. This means that 8 of the PAs will be shut off and cannot be turned
back on until the PA Controller is operational. Once the system is crossed-over, the
remaining PAs will be turned back on.
Loss of one PA Controller will cause the transmitter to foldback due to the system level
imbalance. The most likely cause of foldback in this condition will be the temperature
of the ISO_ABCD isolation load on the ABCD hybrid.
NOTE:
The Power Supplies, PS1, PS2, PS3 and PS4, each power the PAs associated with
one PA Controller. This means that the loss of one power supply will create the
same scenario as loss of one PA Controller.
4.8.5.3
Metering
The PA Controllers are responsible for the metering of the following parameters:
•
PA Current - The current draw of each PA is monitored by measuring the voltage
drop across 0.01 ohm resistors, R11-R18, on the Z-Planes. The resistors show up as
part of the Divider Schematic. This allows the current of each individual PA to be
available on the Diagnostics Display. To check the PA currents press [METERING,
B, B then selecting the desired Z-Plane].
•
PA Supply Voltage - The Voltage of PS1 and PS2 are monitored individually with
fused samples also from the Z-Plane Dividers. To check the PA supply voltages press
[METERING, C, C].
•
PA Gate Voltage - Each individual PA gate voltage can be checked on the Diagnostics
Display by pressing [METERING, C, D then selecting the desired Z-Plane].
•
PA Temperature - There is a temperature sensor on each PA which sends a tempera-
ture sample voltage to one of the PA Controllers. The temperature of each individual
PA can be checked by pressing [METERING, D, B then selecting the desired Z-
Plane].
Summary of Contents for Platinum Z16HD+
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