Nautel VX150, Operation & Maintenance Manual

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VX150 TO VX2 OPERATIONS & MAINTENANCE MANUAL DESCRIPTION
PAGE 2.1.4 VERSION 1.0 2022-12-08
RF Stage
The RF power stage accepts the RF drive input and generates the final RF output.
For VX150 to VX1 transmitters, it consists of Exciter PWB (A1), IPA PWB (A6), PA PWB (A7), PA Low
Pass Filter PWB (A9) and Directional Coupler PWB (A11).
For VX1.5 and VX2 transmitters, it consists of Exciter PWB (A1), IPA PWB (A6), Splitter PWB (A12), two
PA PWBs (A7 and A8), two PA Low Pass Filter PWBs (A9 and A10), Combiner PWB (A13) and Directional
Coupler PWB (A11).
IPA PWB
The IPA PWB amplifies the RF drive signal from the Exciter PWB to the proper level required to drive the
RF amplifier(s) in the PA PWB(s).
For VX150 to VX1 transmitters, the IPA’s output RF drive signal is applied to the System Interface PWB,
where the PA Bias dc voltage is coupled onto the RF drive signal, then it is applied to the PA PWB.
For VX1.5 and VX2 transmitters, the IPA’s output RF drive signal is applied through the System Interface
PWB to the Splitter PWB, where the PA Bias dc voltage is coupled onto the RF drive signals, then they
are applied to PA PWBs.
Splitter PWB
Used in VX1.5 and VX2 transmitters only. The Splitter PWB splits the RF signal from the IPA PWB into
two equal amplitude signals for the two PA PWBs. Two bias signals are coupled to the RF signals to
provide RF + Bias drive signals to the two PA PWBs.
PA PWB(s)
The PA PWB(s) accepts the RF + Bias drive from the System Interface PWB (for VX150 to VX1) or from
the Splitter PWB (for VX1.5 and VX2), and PA volts input from the Power Supply Interface PWB. The RF
output of the PA PWB(s) is controlled by a combination of gate bias set point, RF drive and PA volts. At
low power levels, the RF drive level must be reduced to reduce power below the minimum possible
level at minimum PA volts.
PA Low Pass Filter PWB(s)
The PA low pass filter PWB(s) (A9 and A10, as applicable) is connected to the output of the PA PWB(s)
to reject harmonics prior to being applied to the Directional Coupler (A11) (via the Combiner PWB for
VX1.5 and VX2 transmitters).