Comtech EF Data PCB-4000 - Manual (Page 17)

PCB-4000 1+1 Phase Combiner Revision 2
Introduction MN/PCB4000.IOM
1–3
The block diagrams shown in Figure 1‐2 depict the major components of the 1:1 phase combined
system. (These diagrams employ Comtech EF Data HPODs – High Powered Outdoor Amplifiers – as
the designated SSPAs.)
The PCB‐4000 1+1 Phase Combiner Control Box (PCCB) contains a microprocessor‐based 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.
• It is also through this connection that the PCCB receives it 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. Monitor and Control (M&C) communication with the PCCB is accomplished via
the “SYSTEM COM | J1” connector.
Note: In order 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 1 OUT | J9” and “SSPA 2 OUT | J10”
output connectors.
o
The RF path to the “SSPA 1 OUT | 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. INSTALLATION, STARTUP,
AND TROUBLESHOOTING PROCEDURES for
further information.
o The RF path to the “SSPA 2 OUT | 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). You should not alter any RF cable inside (or outside) of the
box that is part of the RF signal path.