Comtech EF Data PCB-4000A, Installation And Operation Manual

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PCB-4000A 1+1 Phase Combiner
Revision 2
Introduction 1–3 MN-PCB-4000A
The block diagrams shown in Figure 1-2 depict the major components of the 1:1 phase combined
system. (These diagrams employ High Powered Outdoor Amplifiers (HPODs) as the designated
SSPAs.)
The Phase Combiner Control Box (PCCB) contains a microprocessor-based Monitor and Control
(M&C) circuit board to control the system. Interconnection is as follows:
•
The PCCB communicates with each SSPA via control cables that are attached from the
PCCB “
SSPA COM 1 | J2 ” and “ SSPA COM 2 | J3 ” connectors to each SSPA.
•
Through this connection, the PCCB receives its prime power to operate. A +24V signal
from each SSPA is diode OR’ed to provide redundant operating power for the PCCB.
•
A “Y” cable connects to the “ SSPA SW OUT | J5 ” connector for control of the waveguide
switches. M&C communication with the PCCB is accomplished via the “ SYSTEM COM |
J1 ” connector.
To avoid ambiguities, all communication to each SSPA is also accomplished via
the PCCB M&C.
The PCCB provides a weatherized housing for the necessary input RF components. System
interconnection is as follows:
•
An input RF redundancy switch, controlled via the “ RF INPUT SWITCH | J6 ” connector,
selects which RF path is directed to the output.
•
The output RF signal is fed into an in-phase divider, which equally splits the signal in
phase and amplitude to the “
SSPA OUT 1 | J9” and “ SSPA OUT 2 | J10”
output connectors.
o
The RF path to the “ SSPA OUT 1 | J9” output connector contains a manually
adjustable phase shifter. This phase shifter is used to equalize the phase difference
of each SSPA signal path to achieve maximum system output power. It is accessible
via a small cover panel. This critical component is factory set and should only be
adjusted, if needs arise, by carefully following an appropriate alignment procedure.
See Chapter 3. OPERATION and ADJUSTMENT PROCEDURES for
operational and alignment information.
o
The RF path to the “ SSPA OUT 2 | J10” output connector contains a length of
coaxial cable that is factory manufactured to provide equal phase length paths from
the RF input to each PCCB output when the adjustable phase shifter is set to its
midpoint. This provides a maximum adjustable phase range.
There are also several isolators inside the PCCB that maintain good system Voltage Standing
Wave Ratio (VSWR). Do not alter any RF cable inside (or outside) of the box that is part of the
RF signal path.
•
The RF signals from the PCCB are fed to the RF input of the respective SSPA via a set
of phase-matched cables. Again, the phase length (and matching) of these cables is
essential to system operation and no substitutes should be used. The routing should not
be such to cause extreme bends.
•
The output waveguide combining system consists of balanced waveguide lengths, two
waveguide transfer switches, a “Magic-Tee” combiner with termination, and couplers for
test and alignment.