3-2
Operation
Series XT-50, XT-80, and XT-100 Amplifiers
In this mode, the TWT is ready for high voltage to be applied. The Timer Complete
status line is active (low) and the High Voltage ON status line in not active (high).
High Voltage ON Mode
When high voltage is ON (applied to the TWT) RF input signals are amplified and
the High Voltage ON line is active (low). If the High Voltage ON control line is
activated (set low) before the Heater Delay is complete, high voltage will remain off
until the delay is complete.
Fault Mode
This mode exists anytime a condition detrimental to the TWT is detected by the
power supply fault detection circuitry. Any of the following conditions trip the
fault detection circuitry:
•
Excessive Helix Current Fault
. When the power supply detects a Helix
Current fault, it turns OFF high voltage and then tries to turn the high voltage
ON. If the fault persists for three OFF-ON cycles, the fault circuit latches and
the power supply stops automatically recycling. The Helix/Arc Fault line will
remain active (low) at this point. Once the Helix/Arc Fault circuit latches, the
Fault Reset control line must be activated briefly or the High Voltage ON
control deactivated to clear the fault.
•
High Voltage Fault
. The high voltage fault circuit will latch immediately
when a fault occurs. A high voltage fault may be cleared by setting the Fault
Reset control line low or by setting the high voltage ON control high.
•
TWT Over-Temperature Fault
. A TWT over-temperature fault will clear itself
once the temperature of the TWT's collector is reduced to a safe operating level.
High voltage will automatically be enabled when the over-temperature fault
clears (if High Voltage ON control signal is active).
An over-temperature fault should be cause for immediate
maintenance action as it is an indication of a fan failure or
blocked air passage(s).
•
Fan Lock Fault
. This fault indicates that fan rotation is restricted or the fan
has failed.
A fan lock fault should be cause for an immediate maintenance action
as it is an indication of a foreign object jamming the fan or a fan
failure.
•
Interlock Fault
. If the amplifier's cover is removed, an interlock will prevent
high voltage from being applied.
WARNING:
EXTREME CAUTION SHOULD BE USED ANY TIME THE
COVER IS OFF THE UNIT. A SAFE PRACTICE IS TO ASSUME THE HIGH
VOLTAGE IS ALWAYS ON.
