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5.3 Normal Shutoff
When transmission is completed and no other activity is planned for an hour or so, the CHPA's
AC power should be switched off to conserve electricity and prolong TWT life. The following
procedure describes normal shutoff:
1. Press the STANDBY button to place the CHPA in Standby state. Verify that Line 2 of the
display indicates STANDBY.
2. Leave the CHPA in Standby approximately 10 minutes to allow the TWT collector to cool.
3. Switch off the Main circuit breaker.
Note: Repeated cycling of AC power (more than 3 times per minute or 8
times per minute or 8 times per 5 minute period) will result in excessive
inrush current and may trip circuit breaker.
5.4 Basic CHPA Operation
Basic CHPA operation, which requires little interaction with the CHPA, includes features that
are directly available via front panel buttons: user-chosen CHPA states, Control modes, and RF
modes. Refer to Table B-1 in Appendix B for button definitions. Most CHPA features require a
more sophisticated user interface; these features are described in "Special CHPA Functions"
later in this chapter.
5.5 CHPA States and Description
The operation of the CHPA may be divided into several states and sequences. They are as
follows:
•
POST (Power-On Self-Test)—Initial power on.
•
HTD (Heater Time Delay)—Beam-off state while cathode heats to operating temperature.
•
Standby—Normal beam-off state.
•
BONS (Beam On Sequence)—Transition from Standby (beam off) to Transmit (beam on).
•
Transmit—Beam on state (in this state, the CHPA may transmit).
•
BOFS (Beam-Off Sequence)—Transition from Transmit to any beam off state.
•
Fault (Non-latched)—Beam-off malfunction state; the CHPA will recycle to the state prior to
the fault.
•
Fault (Latched)—Beam off malfunction state. Only user intervention will return the CHPA
to a normal operating state.
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