TECHNICAL NOTE – OPERATION OF MT4000 TWTA
10/24/03
TN4000-3
MCL, INC.
28 of 46
4.4.5 Fault & Alarm Trip Levels Set on the Front Panel
Some fault & alarm trip levels associated with an analog display are adjustable by the operator at
the HPA front panel (see the Adjustment Menu Screen paragraph of this document), and through
the Remote or Computer interfaces. These parameters are listed in the table below.
PARAMETER
RESOLUTION
LIMITS
TUBE OV DR FLT LVL
0.1 mW
00.0-FSTD
TUBE OV DR ALM LVL
0.1 mW
00.0-FSTD
RF LOW ALM LVL
NOTE 1
1 Watt
0000-FSFP
RF HIGH ALM LVL
NOTE 1
1 Watt
0000-FSFP
REFLD PWR FLT LVL
1 Watt
000-FSRP
REFLD PWR ALM LVL
1 Watt
000-FSRP
TUBE TEMP ALM LVL
1º C
000-140
PS TEMP ALM LVL
1º C
000-99
FIL U CUR FLT LVL
0.01 A
0.00-5.10
NOTE 1: For these parameters if the encoder is adjusted passed the upper limit OFF
will be displayed on the HPA front panel and the trip level will be disabled.
FSFP =
Full Scale of RF Forward Power meter.
FSRP =
Full Scale of RF Reflected Power meter.
FSTD =
Full Scale of Tube Drive Power meter.
4.4.6 Tube Fault Counter Operation
If the MT4000 is to be left in an unattended earth station, or during a degassing operation, or if
the tube is nearing the end of it’s life the Fault Counter may be turned on to allow the HPA to
automatically reset the tube faults and return to Transmit. When the tube fault counter is enabled
it will count tube electrode faults. If any fault other than those listed in this paragraph were to
occur at any time in the Fault Counter sequence, the fault counter timer would be disabled and
the timer reset. After a tube fault is counted and displayed it will be reset, then after the power
supply has been off for 5.0 seconds the HPA will be commanded back into Transmit. After the
fault is reset & before the HPA is put into Transmit, the HPA will be in the Transmit Selected
mode for about 3 seconds. The fault counter delay time is 5.0 seconds, which allows the power
supply and tube time to cool down. Each time a fault is counted a fault event, reset event, and
transmit event will be placed into the event log.
Faults that will be counted are:
High Voltage Under Volt fault
High Voltage Over Volt fault
Helix Surge Current fault
Helix Run Current fault
