9/15/06
888-2586-001
4-21
WARNING: Disconnect primary power prior to servicing.
Section 4 Overall System Theory
Platinum Z16HD+
hybrid, just above the Z-Planes. These reject loads are called ISO_AB and ISO_CD to
note which Z-Planes they are attached to. These are considered System ISO loads and
their temperature is monitored by both the Master Controller and the PA Controllers.
The Master Controller monitors these for power foldback purposes while the PA
Controllers monitor for protection if the Master Controller is not operational.
4.4.7
"10kW" Final Hybrid Combiner
The outputs of the two Power Blocks are connected to yet another 3dB hybrid combiner
in the bottom of the transmitter just above the power supplies for the total combined
output (in slang terms we call it the “Pizza Box” due to the shape and size). The output
of this combiner is connected to the transmission line Harmonic Filter in the rear of the
cabinet. The reject load for this hybrid is mounted on the large heatsink on top of the
hybrid enclosure in the power supply compartment. The reject load is called
ISO_ABCD since this hybrid is the output of all four Z-Planes combined. ISO_ABCD
has a temperature sensor for monitoring and protection. This is considered a System
ISO load and its temperature is monitored by both the Master Controller and the PA
Controllers. The Master Controller monitors for power foldback purposes while the PA
Controllers monitor for protection if the Master Controller is not operational.
4.4.8
Harmonic Filter
The vertical transmission line in the back of the cabinet contains the Harmonic Filter.
The Directional Couplers are mounted on the side of the filter.
4.4.9
Directional Coupler Assembly
The directional coupler assembly is installed directly before the output from the
transmitter. It consists of 3 directional couplers with two of the couplers adjusted to
produce a sample of the forward output power, and one coupler arranged to provide a
sample of the reflected output power. The isolation, or directivity, of the couplers is
better than 30dB, with 40dB typical. One of the forward couplers is left open for
customer use. The coupling ratio for each of the couplers is given below:
NOTE:
The reflected coupler cannot be interchanged with the other 2 couplers due to the
different coupling ratio for the forward and reflected samples.
•
Forward Coupler - 48.8dB @ 88MHz to 47dB @ 108MHz.
•
Reflected Coupler - 43.8dB @ 88MHz to 42dB @ 108MHz.
(Typical tolerance is +/- 0.1dB @ 108MHz but is not guaranteed since any minor
variation can be factored out by using the calibration procedures).
Summary of Contents for Platinum Z16HD+
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