AR 10013130, Руководство по эксплуатации и обслуживанию

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Model 2000TP2G8B
Rev - 21
Allow the heater warm-up delay to expire. Line three will indicate OFF/READY.
CAUTION:
Do not allow the TWTA to remain in STANDBY for extended periods of
time. If the TWTA will not be used in the OPERATE mode within an
hour, shut the TWTA off. The reason for this precaution is that in the
STANDBY mode, the TWT’s cathode runs very hot since it is not cooled
by electrons boiling off the surface, and small amounts of out-gassing are
not cleaned up by the electron beam. Extended operation in Standby can
result in irreparable damage to TWT!
Push S4 (MORE) three times to go to MENU 4. Verify that the heater voltage and current for TWT #1 are
near their nominal levels. The values of these parameters at the time the TWTA left the factory are logged
on the test data sheet.
Push the OPERATE push-button. You will now see the cathode and the collector voltages rise. Verify that
the grid, collector, and cathode voltages are near nominal. The helix current should be near the nominal value
for no RF drive. Then push MORE or EXIT to go back to MENU 1.
Set the TWTA gain to maximum. Adjust the RF generator to slowly increase the RF drive toward
0 dBm to reach the desired FWD peak power on the display and power meter (connected to sample port). The
forward power reading will become active and reach a maximum reading when peak power output is
achieved. Best performance is obtained when the input RF drive is set at or just below the level that causes
the highest level of peak power output. Do not set input drive above 0 dBm (Input drive above +13 dBm may
damage the unit). The reverse power level should remain below 10% of the forward power, assuming that the
load is properly matched.
An alternate procedure is to pre-set the TWTA gain to minimum, set the RF generator to 0 dBm and then
slowly increase the TWTA gain to set the desired RF output level.
Observe that the helix current is sensitive to the RF drive level of the TWT. It is at a minimum with no RF
drive. The helix current with no drive and with rated RF power output mid-band are logged on the test data
sheet for a specific set of pulse input drive conditions. The value of the helix current under these drive
conditions is a good qualitative indicator of RF and video pulse drive input present.
To shut the system down, turn down the RF generator level below -50 dBm and press STANDBY. Allow the
TWTA to cool down until the TWT temperatures drops below 70°C, and then turn off main power.
3.7 REMOTE IEEE-488 OPERATION
The TWTA is provided with an IEEE-488 interface that permits remote emulation of OPERATE,
STANDBY, and RESET push-buttons as well as access to parameter measurements, system faults, gain
adjustment and control unit status. The Power Save mode (Sleep Mode) provides
remote capability to control
the TWT heater (filament) and to lower the amplifier standby power consumption during non-operational
intervals.
The following tables summarize the commands and the return codes.