Advanced Amplifiers AA-1218G-3.5KW-PT Manuale d'uso - Pagina 10
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Operation
Terminate TWTA RF input and output. Connect external Interface as desired. Apply prime power.
Caution: The TWTA must never be placed in Operate without proper RF termination. This can lead
to TWT oscillations which can permanently damage the TWT.
Power TWTA On:
Press the manual WARM UP button to power the TWTA. The manual WARM UP button will
illuminate. Front panel display will show "Warm up" and the remaining warm-up time in the status
area.
At initial power-up, heater voltage will be less than nominal to limit excessive current drawn by a cold
filament. As the filament warms it will draw less current and the filament voltage will increase until
nominal voltage is reached. Negative Bias voltage is applied to the Grid. Body and Collector supplies
are off. The standard warm-up period is 5 minutes.
Standby from Warm-up:
After the warm-up period has elapsed the TWTA is placed in STANDBY by the main microprocessor.
High voltage supplies and Grid voltage remain unchanged from the WARM UP state. The manual
STANDBY button is illuminated and the WARM UP/OFF button is extinguished. The front panel
display will indicate "Standby" on the status area. The TWTA can be now placed in OPERATE.
Operate:
Press the OPERATE button to place the TWTA in OPERATE state or send the OPERATE command
from the remote computer. The OPERATE button is illuminated and the STANDBY button is
extinguished. The front panel display will indicate "Operate" on the status bar and the background
color will change to green.
The Main microprocessor engages the Collector voltage soon after the OPERATE command is received
and the Body voltage 500 ms after the Collector voltage stabilizes. Then it waits up to 3 seconds for the
Collector voltage to stabilize before going to OPERATE. Both STANDBY and OPERATE buttons are
illuminated during the High Voltage on sequence. The amplifier goes to RESET if the voltages don't
reach the nominal values within allowed time. 8 s after the high voltages have reached their nominal
values, pulses are passed unaltered to the Floating Deck where they are subject to PRF (Pulse
Frequency) and PW (Pulse Width) limiting. The TWT beam current will be present within up to 13.5 s
after the TWTA OPERATE command is sent.
If RF and video pulses (pulsed units) are supplied, the TWTA will produce an amplified RF output.
Standby from Operate:
When placed in STANDBY by user command, the main processor sequentially interrupts video pulses
to the Floating Deck, disengages the Body and Collector supplies and returns the TWTA to STANDBY.
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