AR 10044005, Operating And Service Manual

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Model 5000A225A
2 Rev B
1.3 POWER SUPPLIES
The Model 5000A225A is a modular design with each section having self-contained power supplies. These
power supplies are self-contained, regulated switching units.
The Main Power Amplifier (MPA) unit has a supply pro42V as the main source of power for the
amplifier circuitry. Also included in this unit is a +5V supply for logic and control functions and a +24V
supply that runs the coolant pump, heat exchanger fans and main combiner fan.
The Driver/Control (DCU) section contains a +37V supply providing DC power for the power amplifier
module and for the A8 Regulator assembly. It also contains one other power supply: a unit pro5,
+15, and -15V for control and logic.
1.4 PROTECTION CIRCUITS
Features incorporated into this unit include RF output level protection circuits, thermal protection circuits,
output device current monitoring and limiting of individual power amplifier modules. There is a main system
AC circuit breaker and secondary AC circuit breakers in the Driver/Control unit (DCU) and the main power
amplifier (MPA) unit. Both main switching supplies are short circuit protected. Reaching a threshold of
either of the RF forward (incident) or reverse (reflected) power limit adjustments, which are adjusted to
approximately 5500 watts and 2500 watts respectively, will initiate limiting, or smooth drive level fold-back,
in a low-level stage of the amplifier chain. If the limiting circuits cannot keep the amplifier’s levels below the
limit threshold, the protection circuits will invoke a shutdown of the main power supplies and low-level driver
in the amplifier. Power amplifier modules are monitored for both over-current and under-current. A
RESET
function is provided to permit re-powering of the amplifier in case of transient or temporary activation of the
amplifier’s protection circuitry. The low-level driver and output amplifier subassemblies are thermally
monitored.
The cooling system is monitored and protected. Each power amplifier module incorporates a thermal switch
which will shut down the power supplies in the event of an over-temperature condition. Liquid coolant is
monitored for temperature, flow, and level. Over-temperature of the fluid or low coolant level will shut down
the amplifier and send a notification to the front panel display.
The digital control panel monitors all fault signals, stores and displays any that are invoked and asserts the
required action.