Rf Combining; Control System - Harris Platinum Z16HD+ Preliminary Manual

Section 1 Introduction/Specifications
modules are "hot-pluggable" and can be removed and inserted into an operating
transmitter without removing plugs and cables.
The IPA consists of 2 standard PA Modules, with only one side active at a time to
provide the required drive for the two PA Power Blocks. This means that each power
block has a backup IPA. The transmitter contains sensing, logic and switching circuitry
which will automatically switch from a failed IPA to the remaining one. For even
further redundancy, any PA module can also be used as an IPA module, without
modification.
1.3.3
Each Power Amplifier or PA (one half of a PA module) is combined first in groups of
eight in a compact, "Z plane" isolated combiner. True isolation means that each module
will continue to work into a nominal 50 ohm load regardless of the number of active
amplifiers, for almost zero stress to the amplifiers during fault conditions. There are two
8 way combiners in each "Power Block". The outputs of the 8 way combiners are then
combined in a compact 3dB hybrid. The outputs from the two Power Blocks is
combined in another 3dB hybrid for the full RF output. The 3dB hybrid provides
improved load conditions for the RF modules and tends to absorb power received by the
antenna. This can reduce the amount of RF intermodulation generated by the transmitter
when co-sited with other FM transmitters.
1.3.4
A microprocessor based controller monitors over 100 operating functions of the
transmitter and makes intelligent operating decisions based on operating conditions.
Detailed system information is available using the front panel diagnostic display. The
controller is designed for direct connection to standard parallel remote control systems.
The Controller provides automatic power control, VSWR overload protection,
automatic VSWR foldback, RF power soft start, AC restart and diagnostics. It also
includes built-in logic and controls for automatically switching to the reserve IPA
section, backup BoostPro, or backup exciter if installed. Basic control functions
available even without the main controller are VSWR protection, PA and IPA
protection, transmitter on/off, failsafe and interlock.
The control system for the transmitter is modular and is centered on the backplane
which is also the control panel for the transmitter. Various control printed circuit boards
are plugged into the backplane to fit the transmitter for the configuration being
supplied.
The control system front panel includes an output metering LCD display which can be
used to view Forward power, Reflected power or VSWR, APC (Automatic Power
Control) voltage, PA voltage and PA current. A second LCD window, the Diagnostics
1-6
WARNING: Disconnect primary power prior to servicing.

RF Combining

Control System

888-2586-001
Platinum Z16HD+
9/15/06