Comtech EF Data PCB-4300 - Manual (Page 17)

PCB-4300 1:2 Phase Combiner Revision 2
Introduction MN/PCB4300.IOM
1–3
Figure 1-2 provides block diagrams depicting the major components of the 1:2 phase combined
system. (These diagrams employ Comtech EF Data HPODs – High Powered Outdoor Amplifiers –
as the designated SSPAs.)
The PCB-4300 1:2 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 J2, J3, and J4 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.
• Control of the waveguide switches is accomplished via a “Y” cable at the J5 connector. The
user communicates with the control box via the J1 System Comm connector.
Note: In order to avoid ambiguities, all communication to each SSPA is also accomplished via the
control box 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, SSPA OUT 2 J10, and SSPA OUT 3 J11 output
connectors.
o The RF paths to the SSPA OUT 1 J91 and SSPA OUT 3 J11 output connectors each
contain a manually adjustable phase shifter; these phase shifters are used to equalize the
phase difference of each SSPA signal path to achieve maximum system output power.
They are accessible via a small cover panel. These critical components are factory set
and should only be adjusted, if needs arise, by carefully following an appropriate
alignment procedure – refer to Chapter 3. OPERATION
AND ADJUSTMENT
PROCEDURES for further information.
It is also important for the user to install the individual SSPAs in the correct position
(as aligned at the factory). For installation examples, see Appendix A. ASSEMBLY
KITS.
o The path to 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). The user should not alter any RF cable inside (or outside)
this 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.