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HARRIS
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WARNING: Disconnect and lockout AC primary power prior to servicing
175
Figure
8-1
High
Band
Quarter
Module
8.2 RF Amplifier Modules Theory of Operation
RF amplifier module assemblies are made from quarter modules, each quarter module
has four RF field effect transistors (FETs). Two pairs of push-pull transistors are
operated in parallel. The push-pull operation reduces distortion.
Quarter modules can be connected in various series and parallel combinations. This and
class A or AB bias are utilized to make different types of RF modules:
•
Driver modules - multistage gain units used to amplify a low level signal to the drive
levels needed by the subsequent amplifier stages.
•
525 Watt drivers for analog service. These are used as a high power driver.
•
1000 Watt PA modules - single-stage high power amplifiers which use four parallel
quarter module stages to achieve output powers of 1050 W peak (280 W average).
Different transmitter configurations will utilize one or more of these types of modules.
New Platinum-i transmitters will use the same modules as analog transmitters.
A multi-pin connector, J2, on the rear of each module supplies RF drive, 50 Volts DC,
and ENABLE commands to the module, and returns a fault status signal back to the
transmitter controller. RF output is passed through a separate coaxial connector. The
