TECHNICAL NOTE – OPERATION OF MT4000 TWTA
10/24/03
TN4000-3
MCL, INC.
45 of 46
Never activate transmit unless an RF load is connected to the RF output.
Avoid operating the system in standby for more than 60 minutes; use
the Filament Off control for long periods of Standby. See 46A0009
Extending Tube Life Information this document is include as an
appendix to TN4000-5 Preventative Maintenance for MT4000.
6.
Insure that the RF input to this system is at the desired frequency and that it is a frequency
within the TWTA operating frequency band.
7.
Depress the Transmit switch (HV On) to activate the high voltage. The “Transmit”
switch will illuminate.
8.
Set the RF On/Off control to the On position.
9.
Set the exciter output to RF On.
10.
Go to the Gain screen very carefully increase the TWT RF input drive until rated RF
Forward Power is obtained (Consult the MT4000 test data for the rated output power to
be expected) from the amplifier system while staying within the TWT current and voltage
limitations. Monitor the output reflected RF power to insure that the transmission line is
reflecting less than 10% of the output forward power.
11.
If the system reaches rated output before reaching maximum gain, it will be necessary to
further reduce the RF output of the exciter.
12.
If the system reaches maximum gain before reaching rated output power, slowly increase
the exciter output until the system reaches rated output power.
Under no circumstances should the TWTA be driven to an output of greater
than the system’s rated output. This will result in degradation or permanent
damage to the TWT.
13.
Once the exciter output has been set so that the system reaches full rated output with the
MT4000 gain control set to maximum gain, the exciter output should be locked in place
by mechanical means or by way of a tamper proof seal. The MT4000 gain control should
then be used in the future to make adjustments to the system output power.
CAUTION
CAUTION
