888-2408-002 4-43
WARNING: Disconnect primary power prior to servicing.
Overall System Theory
4.7.4.2 Metering
The PA Controllers are responsible for 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 A,B then B or C (to check Z-plane A or B)].
• PA Supply Voltage - The Voltage of PS1 and PS2 are monitored individually with
fused samples also from the Z-Plane Divider. To check the PA supply voltages
press [METERING B,C].
• PA Gate Voltage - Each individual PA gate voltage can be checked on the Diag-
nostics Display by pressing [METERING B,D then C or D (to check Z-Plane A
or B)].
• PA Temperature - There is a temperature sensor on each PA which sends a tem-
perature sample voltage to one of the PA Controllers. The temperature of each
individual PA can be checked by pressing [METERING C,A then C or D (to
check Z-Plane A or B)].
• PA ISO Resistor Temperatures - VTEMP PA1 through VTEMP PA8 -Each ISO
resistor has a thermistor, used as a temperature sensor, attached to it for metering
and fault monitoring. To check the ISO resistor temperatures press [METERING
C,C then B or C to check Z-Plane A or B]. A rise in the ISO resistor temperature
indicates an imbalance in the phase or amplitude of a PA output.
NOTE:
The temperature of the different PA ISO resistors (A1-A8 and B1-B8) can
vary quite a bit, but are considered okay if they are under Ambient + 75°C.
Az and Bz, which also show up in these screens, are the temperature indications for
the 2.5kW, 2 way combiner isolation load resistors. A rise in this temperature would
indicate an imbalance between the outputs of the two foursomes on that Z Plane.
ISO_AB_LOAD is the temperature of the reject load on the 3dB hybrid which
combines the outputs of the Z Planes.
To Next Page
Loading...