9/15/06
888-2586-001
4-13
WARNING: Disconnect primary power prior to servicing.
Section 4 Overall System Theory
Platinum Z16HD+
The IPA modules plug into the IPA Backplane Boards. This board interfaces all inputs
and outputs for the IPA module. It is also responsible for:
•
Main/Alternate IPA switching (active with standard, dual IPA configuration) For IPA
Status press [STATUS A,B]. This screen can also be used to manually switch IPAs.
•
Monitoring of IPA temperature, voltage, current and forward power.
•
Splitting of the IPA output into 2 equal amplitude signals 90 degrees out of phase, by
way of a 3dB hybrid, to drive the Z Plane dividers.
•
Air flow sensing
•
Ambient temperature sensing
•
IPA interlocking
4.4.2.5
Main/Alternate IPA Switching
Selection of IPA_AB1 or IPA_AB2 (both input and output) is done via RF switches K2,
K3 and the IPA DRIVER SELECT control signal from the Master Controller via the
Life Support Board.
K2 switches the input RF drive from the Exciter Divider Board to IPA_AB1 or
IPA_AB2 while K3 selects the active IPA RF output. The control signal, IPA DRIVER
SELECT, is normally low which places K2 and K3 in the IPA_AB1 position as shown
on the schematic. If IPA DRIVER SELECT goes high, K2 and K3 will be energized and
switch to the IPA_AB2 position. If the Master Controller detects a loss of RF output
from the active IPA it will automatically switch to the second IPA. IPA switching can
also be done manually via the Diagnostics Display.
4.4.2.6
IPA Monitoring
Each IPA Backplane Board provides for monitoring and/or interfacing of 4 main IPA
parameters:
•
IPA temperature (VTEMP_IPA1 and/or VTEMP_IPA2). If the temperature exceeds
100°C, the controller will mute the transmitter and/or switch to the alternate IPA. The
sensor is actually located on the IPA board, but is interfaced through the IPA Back-
plane.
•
IPA supply voltage (Vd_IPA_SAMPLE). A monitoring sample is sent to the control-
ler through fuse F2. The Supply voltage for each IPA is diode or’ed from 2 PA sup-
plies for redundancy. IPA_AB1 and AB2 are powered from Power Supplies 1 and 2
while IPA_CD1 and CD2 are powered by Power Supplies 3 and 4.
•
IPA current (Id_IPA). IPA current is measured by measuring the voltage drop across
the series resistor R1. The IPA current fault threshold is set at 14.0 amps via software
on the Master Controller.
Summary of Contents for Platinum Z16HD+
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