Comtech EF Data PCB-4300 - Manual (Page 19)

PCB-4300 1:2 Phase Combiner Revision 2
Introduction MN/PCB4300.IOM
1–5
The gains of the three amplifiers are also equalized at the factory to provide optimum system
performance. The PCB-4300 software has a command that reads the stored factory gain of each
SSPA and adjusts “offsets” to equalize the gains between the three SSPAs. These Amplitude
Offsets – AOF1, AOF2, and AOF3 – are often further fine-tuned at the factory to provide
optimum system performance (see test datasheet for specific system offsets).
It is important to reiterate that these offsets, adjusted at the factory and stored in non-volatile
memory, are transparent to the user; they should not need further adjustment in end user
applications unless an amplifier has been replaced.
1.3.2 System Switching
The possible combinations of which two SSPAs are “online” and directed to the system waveguide
combiner output, versus which SSPA is offline, are as follows:
• 1+2 online (SSPA #3 offline);
• 1+3 online (SSPA#2 offline);
• 2+3 online (SSPA #1 offline).
There are two software modes that control which two SSPAs are online versus which SSPA is
offline: “automatic” and “manual”. Either mode is invoked by the state of the FoRCe (FRC=)
command (see Appendix B. REMOTE CONTROL). Note the following:
• FRC=00 – This command is the factory default and executes “automatic” mode, whereby
the two SSPAs that are online and combined will generally be the first two that “clear” their
faults; i.e., the first two SSPAs that are powered on. (Refer also to the PRF setting
description below.) Should a fault occur in an online unit while FRC=00, the offline unit
will automatically switch in place of the faulted unit, maintaining full system output power.
• FRC=XX – Where FRC=00 is the automatic mode, when it is desired to force two specific
SSPAs online, executing this command puts the system in “manual” mode and combines
the output of the two selected SSPAs. This is accomplished by sending this command,
where XX = 12 (1+2), 13 (1+3), or 23 (2+3).
Manual mode also implies that, if one of the online units fail, a switchover to replace the
faulted unit with the offline unit will NOT occur automatically.
(Note that the FRC command is also useful, should system re-alignment be needed – i.e.
the command indirectly directs one SSPA to the offline port for easy characterization and
measurement.)
The recommended and default setting is FRC=00.
PRF=XX – The PReFerred command, where XX = 00, 12, 13, or 23, affects the possible
online/offline states. Note the following:
• If the setting is PRF=00, there is no “preferred” condition, and the first two SSPAs without
faults detected by the PCB-4300 will be directed online.
• If PRF is something other than 00 – e.g., PRF=13 – then, if at any time both units 1 and 3
have no faults, they will be switched online.
The recommended and default setting is PRF=00.