VS300 Operations and Maintenance Manual
Description
Page 1-2
Issue 8.0 2016-03-01
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 PWB 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.
LVPS module
See also electrical schematic Figure
SD-1
. The LVPS module (U3) converts the ac input voltage to the
regulated low voltage dc supplies. The +5 V and +15 V regulated outputs of the supply are applied
throughout the transmitter.
+48 V power supply
See also electrical schematic Figure
SD-1
. The +48 V power supply module (U4) converts the ac input
voltage to a reg48 V dc supply for the pre-amp PA PWB, and the cooling fan.
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, +48 V supply and LVPS) 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 PWB and the cooling fan.
Dc current samples of the PA and pre-amp 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 fan.
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.
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