Series XT-50, XT-80, and XT-100 Amplifiers
Operation
3-1
C
HAPTER
3: O
PERATION
General
An external control and monitor unit must be used to operate the XT-50 and XT-
100 series amplifiers. Control and status signals are accessed via a 32-pin
interface connector (J1).
It is recommended that operating time (standby and beam on),
operating conditions (power level) and maintenance actions be
recorded in a power amplifier log.
Operating Modes
There are five amplifier operating modes:
•
Heater Delay (FTD)
•
Heater Standby
•
Standby
•
High Voltage ON
•
Fault
Heater Delay Mode
When power is first applied to the amplifier, voltage is applied to the TWT's
heater. The TWT's heater must be at operating temperature in order for the tube to
function properly. The typical warm-up period is three minutes. During this
warm-up period, the Timer Complete status line will not be active. When the
heater delay is complete, the Timer Complete status line will go active (low).
If there is a power failure, the high voltage will be kept off for a period proportional
to the prime power off-time. At the end of this period, the high voltage will be
automatically applied (assuming that the High Voltage ON control line is active).
Heater Standby Mode
Heater Standby is enabled when the Heater Standby control line is set low. When
prime power is first turned on, full heater voltage is applied during the Heater
Delay mode. At the end of the Heater Delay mode, the heater voltage is reduced if
the high voltage is OFF, and Heater Standby is enabled. The heater voltage
reduction feature enhances tube life when the amplifier is the backup unit in a
redundant configuration. In this mode, the TWT is ready for high voltage to be
applied. Heater voltage will return to normal when High Voltage ON is enabled or
Heater Standby is disabled (set high).
Standby Mode
