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72 205486 REV F Operations Manual, HPA2, Compact Outdoor SSPA
8.3 1:1 Fixed Phase Combined System with L-Band Input
The basic 1:1 Fixed Phase Combined system topology is very similar to a 1:1
redundant system and is shown in Figure 8-5. When in Automatic mode the waveguide
switches (S1& S2) either direct the each amplifier output to the waveguide phase combiner
or, if lower output power is required, bypass the combiner and send an individual amplifier
output to the system output. The system shown in Figure 8-5 utilizes a chain redundancy in
which the faults for BUC1 and HPA1 are linked, as are BUC2 and HPA2 faults.
If a fault were to occur with either component in the chain, both components would be treated
as faulted, and would cause a switchover to the operational chain. If the system is operating
in phase combined mode and a BUC or amplifier enters a fault condition, the system will
switch to the operational thread. This provides a soft fail mode and results in a power
decrease of 3dB to the system output power.
The BUC switch (SW3) is part of the converter assembly and is not controlled by the FPRC.
This switch is driven by the amplifiers when a fault is detected and will be driven to place the
operational BUC online without user intervention.
The system utilizes a chain redundancy architecture for fault handling. If a fault occurs in a
BUC or SSPA, the system will switch to the operational chain. This offers redundancy in the
L-Band portion as well as the SSPA portion of the system.
This system may also be operated via manual mode. This mode of operation may offer some
benefits over automatic operation. When in manual mode, the amplifiers will not switch out of
Phase Combined Mode or switch to the operational amplifier without user intervention if an
HPA fault occurs.
However, if a BUC fault occurs, the HPAs will direct Switch 3 to place the operational BUC
online. The fault indication will still be present on the front panel of the FPRC, but the system
output would be unaffected by the fault, thus indicating to the user that the failure is with the
BUC and not the HPA.
Figure 8-5: 1:1 Phase Combined System with HPA control of BUC redundancy
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