Nautel VS1, Operation And Maintenance Manual

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VS1 Operations and Maintenance Manual Description
Page 1-2 Issue 3.1 2013-10-01
Power supply module
See also electrical schematic Figure
SD-1
. Power supply module U2 converts the ac input voltage to a
regulated dc supply (PA volts) for the PA PWBs (A6 through A9) in the RF power stage. The power
supply module is rated for a nominal 2000 W and provides an output voltage between 7 and 53 V
(typically 48 V). The module regulates the output voltage based on a
PA Volts Control input from the
exciter/control PWB (A1). The module has a built-in cooling fan, senses excessive temperature
conditions, and applies a
PS Temp alarm signal to the exciter/control PWB. The module also senses
out-of-regulation on the ac input and dc output, and applies PS Ac Fail and PS Fail alarm signals to
the exciter/control PWB. All three alarm conditions cause the power supply to shut itself down, thus
inhibiting the transmitter's RF output.
+48 V power supply
See also electrical schematic Figure
SD-1
. The +48 V power supply module (U3) converts the ac input
voltage to a reg48 V dc supply for the pre-amp/IPA PWB, cooling fans, and the dc-dc
converters on the power supply distribution PWB, which p5 V and +15 V to circuitry
throughout the transmitter.
PS distribution PWB
See also electrical schematics Figures
SD-1
and
SD-3
. The PS distribution PWB (A2) interfaces
between the dc power supplies (power supply module and +48 V supply) and the rest of the
transmitter. It distributes the power supply module output to the PA PWB, and distributes the +48 V
output to the pre-amp/IPA PWB and the cooling fans.
Dc current samples of the PA, pre-amp and IPA power supplies are measured on the PS distribution
PWB and provided to the exciter/control PWB over an SPI bus.
Status and alarm outputs from the power supply module (U2), consisting of PS Present , PS Ac Fail , PS
Temp and PS Fail , are applied to the PS distribution PWB and provided to the exciter/control PWB
over an SPI bus.
A fan enable circuit on the PS distribution PWB controls the application of +48 V to the cooling
fans. The exciter/control PWB (A1) provides a
Fan Enable signal that enables or disables the fan
voltage when the RF power stage is on or off, respectively.
Dc-dc converters on the PS distribution PWB convert the +48 V provided by the +48 V supply to
+5 V and +15 V, which is then distributed to circuitry throughout the transmitter