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Each operating state is described in greater detail in the following
text.
5.6.1
POST
The microprocessor-based controller performs a list of tests that
establish its ability to control and monitor the amplifier. Some
areas covered by POST include checking validity of information in
the battery-backed RAM, EPROM checksum, and other controller
specific aspects. During this test the amplifier will accept no user
inputs that affect the beam state.
If there is no POST failure, the amplifier starts the heater time delay
cycle (HTD).
If there is a POST failure, the system halts at the failed test and
reports the error (FAULT LED lights).
5.6.2
Heater Time Delay (HTD)
HTD (Heater Time Delay) allows the TWT heater to warm the
cathode to its operating point. HTD is nominally 3 minutes, but
can be a shorter period after a prime power failure as follows:
HTD proportional time delay:
Heater Reduce is off during this time.
If the TRANSMIT state is commanded during the HTD cycle, the
amplifier will automatically transition to the TRANSMIT state
when the cycle is complete (if there is no fault).
If a fault occurs during HTD, the unit will transition to the Fault
state. The HTD countdown clock continues after a fault occurs.
5-6
If time off <5 seconds, no HTD.
If 5 seconds<time off<1.5 minutes, HTD =
1.5 x time off.
If time off >1.5minutes, HTD = 3 minutes.
O P E R A T I O N
Installation and Operation Manual
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