Harris Atlas DVL400, Technical Manual

Page: 22 / 180

1-8 888-2473-001 2/25/03
WARNING: Disconnect primary power prior to servicing.
Section 1 Introduction ATLAS Series™
1.2.4 PA Module
The Atlas Series™ PA Module utilises LDMOS amplifiers to produce up to 460W
average power output. Each module weighs approximately 20.5kg and can be un-
plugged while the transmitter is running. A single cabinet Atlas Series™ transmitter
can have 1, 2, 3, 4, 6 or 8 PA modules to achieve the various power levels shown in
Table 1-1. The 2 cabinet version will have either 6 or 8 modules per cabinet. A
block diagram of the PA module is shown in Figure 1-4.
Each PA module consists of the following components:
a.
PA Module Controller Board - Responsible for all monitoring and protection
of the module. Reports to the transmitter Main Controller via the CAN bus
but is also connected to the parallel control lines in case the CAN bus is not
operational.
b. Phase and Gain Board - Provides for module phase and gain adjustments to
minimise module combiner reject power. Also provides for cabinet phasing
for the 2 cabinet transmitters to minimise cabinet combiner reject power.
c. DC Distribution Board - Provides FET switching of the +32Vdc and sensing
of driver and pallet currents.
d. Pre-driver Pallet - Provides enough power to drive the 2 way splitter and the 2
driver pallets.
e. Two (2) LDMOS Driver Pallets - Provide enough power to drive the 4 way
splitters and the inputs to the power amplifier pallets.
f.
Pallet Splitter and Combiner - Actually two 4-way splitters and one 8-way
combiner.
g. Eight (8) LDMOS Amplifier Pallets - When combined, they provide up to
460 watts of average power at the output of the module.
h. Liquid Cooled Cold Plate - Mounted directly to the 8 LDMOS power ampli-
fier pallets for cooling.
i.
RF Output Directional Coupler - Samples both Forward and Reflected power
for metering, module ALC and module VSWR protection.
Each Atlas Series™ PA Module is a self-contained 460W transmitter (except for the
power supply) with its own internal control, monitoring and protection. The
modules only receive basic On/Off, Mute, Restart, Phase and Gain commands from
the transmitter control system. This means that each module will protect itself
without relying on the system controller.