Harris Maxiva ULX COFDM Series, Technical Manual

Page: 166 / 308

4-30 888-2629-200 10/6/10
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation
Maxiva ULX COFDM Series
Figure 4-10 Predriver Module Photo (module removed from Predriver assembly)
The predriver assembly holds two predriver modules. The modules are redundant and
hot swappable. See photo in Figure 4-10 on page 4-30 to aid in identification of
predriver module components.
The single rack unit predriver assembly has one RF input and two RF outputs, see
Figure 4-11 on page 4-31 for a schematic orientated block diagram of the predriver
assembly. It features two predriver trays (modules), each of which drives its own IPA.
The RF input to the predriver assembly feeds a two way splitter, the output of which
feed the two predriver trays. The assembly is designed so that one predriver tray can be
removed for servicing while the transmitter operates from the other predriver tray.
It should be noted here that only one IPA drives the PA, the other is terminated in a load.
The IPA outputs feed a coax switch, which is controlled by the power supply monitor
board in the TCU assembly. This allows either IPA to drive the PA assembly.
The interconnect board is the interface between the transmitter cabinet wiring and each
predriver tray. Each predriver tray has a connector, mounted on its interface board,
which mates with a connector on the interconnect board. The interface board connects
to the four boards of the predriver tray.