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HARRIS
888-9058-001
WARNING: Disconnect and lockout AC primary power prior to servicing
25
60 kW Systems, 10% Aural (standard)
The AGC module output feeds a phase and gain module. In high band systems, the
two outputs are then fed to two preamps. In low band transmitters, the preamps are
not necessary.
Each of the two outputs feeds a driver module. The driver outputs are each split in
four-way dividers, for a total of eight outputs, and the outputs drive an array of eight
PA modules. The PA outputs pass to four-way power combiners, whose outputs are
combined in a 3 dB quadrature hybrid used as a two-way combiner. The combined
output passes through a harmonic filter before being sent to the optional diplexer.
1.2.11 Transmitter Output Networks
The transmitter output network performs three functions: filtering harmonics from the
outputs, removing color subcarrier remnants from the vestigial sideband, and combining
the aural and visual outputs into a common antenna feed for transmission. Two common
configurations exist:
10 kW Systems
A combination color notch filter/notch diplexer (optional) receives the aural and
visual outputs and combines them. The output then passes through a harmonic filter
to the antenna system.
15-60 kW Systems
Two harmonic filters are used: one in the visual path, and one in the aural path. The
output of the visual harmonic filter feeds a color notch filter. The outputs of the aural
harmonic and visual color notch filters feed a notch diplexer (optional),whose output
passes to the antenna system.
1.3 Transmitter System Theory of Operation
1.3.1 Control System
The transmitter uses a distributed architecture control system. This means that some
transmitter sub-systems include self monitoring and protection and report to the Main
Controller for display on the GUI (Graphical User Interface) and to a remote interface.
The heart of the system is the 376 Micro Module and the XC95288XL CPLD which is
used for control and monitoring interface.
1.3.1.1 Main Controller Board
This board is responsible for transmitter control and monitoring. The Main Controller is
responsible for system level control (multiple sub-systems) since it is the only part of the
control system which can monitor the entire transmitter. This printed wiring board is
mounted just below the top of the cabinet and also serves as the customer and system Input