TECHNICAL NOTE – OPERATION OF MT4000 TWTA
10/24/03
TN4000-3
MCL, INC.
38 of 46
4.7 Optional Local Interface Override
The Local Interface Override is an optional CCA which when activated will temporarily provide
rudimentary emergency control of the amplifier in the event of a failure of the VFD display,
membrane panel, or the controller.
Use of the Local Override turns off automatic timing and some protection functions.
Use of the Local Override should only be in the event of a failure.
4.7.1 Status to Other Interfaces During Local Override
When the HPA is switched into Local Override the local panel microprocessor will not be
switched off. As long as the local panel microprocessor did not fail, the local panel will be able
to provide status, however no control inputs will be accepted from the membrane panel. As long
as the local panel microprocessor did not fail, the diagnostic, computer, and remote interfaces
will be able to provide status, but no control will be available through those interfaces.
4.7.2 Local Override Controls
The following controls will be present on the Local Interface Override:
Transmit push button
Standby/Reset push button
RF On/Off switch (two position, latched)
RF Attn. increase/decrease switch (two position, momentary)
Override switch (two position, latched)
4.7.3 Local Override Status
The sample port on the HPA front panel provides forward power status. There is one tri-color
status LED on the Local Override assembly. The indications on the status LED will be as shown
in the table below.
HPA OPERATING MODE
STATUS INDICATION
Delay
Flashing Yellow
Delay with a Fault
Flashing Red
Standby
Continuous Yellow
Fault
Continuous Red
Transmit
Continuous Green
CAUTION
