AR 10012510, Руководство по эксплуатации и обслуживанию

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Model 200T8G18A/250T8G18
6 Rev D
Amplifier gain is determined by the solid state preamp (SSA), which has a voltage-controlled attenuator. The
control head determines the output of a digital-to-analog converter (DAC) on the HPA interface board. The
output of the DAC controls the SSA attenuator. The remote control board (A24369-000) mounted behind the
front panel is provided with a circuit that increases the attenuation so that reverse power is limited to a safe
level (on the order of 20 to 50 watts). In emergency bypass operation (see section 3.7) the attenuator signal is
provided locally on the remote control board. The foldback circuit remains on line in emergency bypass
operation.
2.3 DESCRIPTION OF THE POWER SUPPLY
The TWT power supply is of modular construction. Low voltage power for logic and control of the entire
power supply assembly, the preamplifier, and the HPA interface board is provided by the low voltage power
supply module (A23687-001). Control logic and TWT protection circuits are contained in the HPA logic and
Control Assembly (A16485-000).
The Heater Power Supply Module (A10010-000) powers the TWT DC heater. Bias and pulse top voltage for
the TWT grid are provided by the Modulator Assembly (A21422-101).
The high voltage power supply consists of the following: the Power Factor Correction module (A23683-000)
converts line voltage to DC for the high voltage switching supply. Switching is controlled by the Pulse Width
Modulation (PWM) Board (A10017-500). The high voltage transformer and rectifiers are contained in the
High Voltage Diode/Cap Assembly (A22818-002). The high voltage DC is filtered in the HV Filter Assembly
(A21461-000).
Interconnects between the power supply modules are through a motherboard. It is installed in a finned heat
sink assembly to which the modules are bolted. The heat sink is cooled by the incoming cabinet air. The Heat
Sink/Motherboard assembly is A24357-000.