Comtech EF Data HPCST-5000 - Manual (Page 120)

TWT Amplifiers High-Power TWTA Satellite Terminals
4–2 Rev. 1
4.1 Operation and Control
4.1.1 Control and Status Interface
TWTAs are externally controlled. The TWTAs do not include any control switches or
status indicators for operator use. Refer to Chapters 5 and 6 for information on external
control and status indicator interfaces.
Optional remote control panels, the HPC-1200 (used for single thread systems) and the
HPC-1110 (used for 1:1 redundant systems), includes all switches necessary to operate
the amplifiers. For details, refer to Chapter 5 and 6, respectively.
An external control and monitor unit should be used to operate the TWTAs. Control and
status signals are accessed via a 32-pin interface connector (J1).
Note: It is recommended that operating time (standby and beam on), operating
conditions (power level), and maintenance actions be recorded in a power amplifier log.
4.1.2 Operating Modes
There are five amplifier operating modes:
•
Heater Delay
•
Heater Standby
•
Standby
•
High Voltage ON
•
Fault
4.1.2.1 Heater Delay
When power is first applied to the amplifier, voltage is applied to the TWT heater. The
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 is not active. When the heater delay is complete, the Timer
Complete status line becomes active (low).
If there is a power failure, the high voltage is kept off for a period proportional to the
prime power off-time. At the end of this period, the high voltage is automatically applied
(assuming that the High Voltage ON control line is active).