Harris Maxiva ULX, Техническое руководство

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WARNING: Disconnect primary power prior to servicing.
Section 1 Introduction
Maxiva ULX COFDM Series
e.
Splitter Board - The splitter board equally divides the RF signal between four (4)
power amplifier pallets. The splitter is broadband (covers TV band IV/V). The
splitter board also delivers a detected RF sample to the monitor board to indicate
input power level and provide protection from excessive input drive power.
f.
Signal Distribution Board - Signal Distribution Board serves to route analog and
digital control and monitoring data between four (4) PA module board subassem-
blies, monitor board, PA pallets, connector I/O board, and 4-way splitter board.
g.
LDMOS Amplifier Pallets - There are four (4) single stage amplifier pallets
operating in parallel in the PA module. When combined, they provide up to 800
watts of average power at the output of the module.
h.
Combiner Board - The board combines the RF outputs of the four (4) amplifier
pallets, and delivers the combined signal to the output port. The combiner is
broadband (covers the entire TV Band IV/V) and requires no tuning. The com-
bining of the signals is accomplished using hybrid combiners in series. The first
stage is a 2-way 3dB hybrid, the second stage a 2-way 4.77dB hybrid, and the 3rd
stage is a 2-way 6dB hybrid. The use of reject loads in conjunction with the
hybrids allows continuous operation of the PA Module in the event of a PA Pallet
failure. The combiner contains Forward and Reflected signal directional couplers
at its output. Detector circuits deliver the forward and reflected output samples to
the Monitor Board, which indicates the forward power level in dBm and uses the
reflected signal for VSWR monitoring and VSWR fault protection for the mod-
ule. Another directional coupler provides an attenuated sample of output RF sig-
nal to an optional coaxial port at the front of the PA module.
Each Maxiva COFDM PA Module is a self-contained 550W transmitter including the
power supply with its own internal control, monitoring and protection.
The modules
only receive basic On/Off, Mute, & Restart commands from the transmitter control
system. This means that each module will protect itself without relying on the TCU.
1.2.6.1 Module Control
The primary method for control and monitoring of the PA Modules is via the individual
50 conductor ribbon cable bus to one of the two TCU assembly PA Interface boards.
These busses are called Drive A (for preamp A and IPA A), Drive B (for preamp B and
IPA B), and BP 1 through BP 4 (for PA backplanes A5, A6, A8, and A9 respectively).
Each module contains a CPLD based monitor board that is responsible for reporting
faults back to the TCU and for taking action when the ON/STBY command is issued
from the TCU. The cabinet bus connects to each PA and IPA Module backplane, but it
is only used for the PA_voltage_select line, which sets the DC output voltage of each of
the eight AC to DC converters in the IPA and PA modules. The output can be switched
between 44, 46, 48, or 50 VDC, depending on the operating frequency.