TECHNICAL NOTE – OPERATION OF MT4400 TWTA
08/10/2004
TN4400-3
MCL, INC.
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4.11.2 Procedure to Limit RF Input to the HPA
1.
Rate Power No Attenuation
With the HPA attenuation at minimum, measure the amount of power required to drive
the MT4400 system to rated power (this is also shown on the data sheet sent with the
equipment).
2.
Exciter Adjustment
Set the exciter at this level, and lock all exciter output adjustments permanently. Use
devices that must be removed to readjust output. Alternately, set exciter at maximum and
insert attenuation in the line to limit power available at the TWTA.
3.
MT4400 Trip Levels
The Tube Overdrive Fault and the Tube Overdrive Alarm levels were set by MCL to
protect the TWT. If the Tube Overdrive Alarm occurs, this is an indication to the
operator that the tube drive level is approaching the Tube Overdrive Fault. Once the tube
drive level has exceeded the Tube Overdrive Fault level, the HPAs RF switch and high
voltage power supply will both be turned off until the RF drive level is backed down.
To change the Tube Overdrive Fault level from the factory set level
may result in degradation or permanent damage to the TWT.
CAUTION
