CHPA SERIES
1-8
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1.4.7
Control and Display Modules
The Control and Display modules are designed to assure correct operation of the power
amplifier with minimal operator training. These microprocessor-based modules provide
automatic sequencing of CHPA operation and monitoring and control of all critical parameters
via both the front and rear panel interfaces. Flash RAM allows firmware updates to be made
without opening the unit.
The Display Module communicates to the user all necessary information required to monitor
and control the amplifier. Measured readings such as reflected RF power, helix voltage, helix
current, attenuator setting, and forward RF power are all available via the alphanumeric
display. Status LEDs are also included on the panel.
Detailed fault information and user-settable interface parameters are available to the user
through a menu system.
The Control Module is central to the CHPA. All control, input/output, and decision making,
with the exception of critical module, level decisions, is done by the Control Module. All rear
panel user interfaces are also communicated to via the Control Module. To survive AC power
loss, all user settings and operating parameters such as RF trips, TWT operating voltages, serial
port baud rate, and PIN diode attenuation setting, etc., are stored in the battery-backed random
access memory (RAM).
1.5 LRU Philosophy
The maintenance concept employed in the CHPA series is to localize a malfunction or circuit
failure down to the level of an LRU (line replaceable unit), extract the LRU, and replace it with
an equivalent part provided in the spares kit. This procedure can be completed in the field
without resorting to the costly practice of returning the entire CHPA to the depot for servicing.
The philosophy is to configure the LRUs as building blocks with a specific function that can be
monitored by sensors and fault indicators on a real-time basis.
The CHPA contains circuitry to protect itself from operational damage caused by abnormal AC,
DC, RF faults, or insufficient cooling.
Personnel safety is of utmost importance and is safeguarded by proper grounding and also by
access interlocks and covers that prevent physical entry into the high-voltage sections.