User's Guide

VHF Transmitter Amplifi er Instruction Manual
IM21-VT3150AMP
1
GENERAL
INFORMATION
Introduction
The VHF Transmitter Amplifi er provides the
fi nal stage of RF amplifi cation and fi ltering for
the entire VHF Transmitter VT-3 132 - 174
MHz family and the VT-4 P25 Digital VHF
Transmitters. The amplifi er has two distinct
frequency ranges: 132 to 150 MHz, and 150 to
174 MHz with continuously adjustable 2.0 to 8.0
Watts output power. This Amplifi er is housed in a
machined aluminum case that ensures optimum
RF shielding, provides a good ground, and also
acts as a heatsink.
Additionally, the VHF Transmitter Amplifi er is
equipped with output power and VSWR sensing
lines that can be individually confi gured as open
collector or linear outputs. The internal VSWR
sensor protects the amplifi er from high antenna
VSWR by approximately halving the amplifi er’s
RF gain when a VSWR overload condition is
present.
The Lowpass Filter Board provides output
fi ltering for the VHF Transmitter Amplifi er.
The Lowpass fi lter assembly is mounted in a
separate compartment of the amplifi er case
in order to provided maximum attenuation of
harmonic and other spurious signals.