User Manual
Table Of Contents
- 1GENERAL
- 1.1Introduction
- 1.2Performance Specification
- 2THEORY OF OPERATION
- 2.1Amplifier Operation
- 2.2Power Requirements
- 2.3RF Circuitry
- 2.3.1VT-3/150 Lowpass Filter
- 2.4Power Control Circuitry
- 2.5Power Sensing Circuitry
- 2.5.1Output Power Sense
- 2.5.2VSWR Sense
- 2.5.3VSWR Overload
- 3VT-3/150 AMPLIFIER ALIGNMENT
- 3.1General
- 3.2Repair Note
- 3.3Recommended Test Equipment List
- 3.4Printed Circuitboard Numbering Convention
- 3.5Standard Factory Settings and Jumper Configuration
- 3.6VT-3/150 AmplifierAlignment
- 3.6.1General
- 3.6.2VT-3/150 Amplifier Adjustment
- 3.6.2.1General Set-Up
- 3.6.2.2Output Power Alarm (Forward Power)
- 3.6.2.3Output Power
- 3.6.2.4Antenna VSWR Alarm (Reverse Power)
- 3.6.2.5Antenna VSWR Overload
- 3.6.2.6Procedure Verification
- 4ILLUSTRATIONS AND SCHEMATIC DIAGRAMS
- 4.1VT-3/150 VHF Amplifier Component Layout
- 4.2VT-3/150 VHF Amplifier Schematic Diagram
- 4.3VT-3/150 VHF Lowpass Filter Component Layout
- 4.4VT-3/150 VHF Lowpass Filter Schematic Diagram
- 5PARTS LISTS
- 5.1VT-3/150 Amplifier Electrical Parts List
- 5.2VT-3/150 Low Pass Filter Electrical Parts List
- 5.3VT-3/150 Amplifier Mechanical Parts List
- 6REVISION HISTORY
DE
DANIELS
ELECTRONICS
VHF Amplifier Instruction Manual VT-3 132 - 174 MHz
1-1
1
1
GENERAL
1.1 Introduction
The
VT-3/150
Amplifier
provides the final stage of RF
amplification
and
filtering
for the
entire
VHF
Transmitter
VT-3 132 - 174 MHz family. The
amplifier
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.
The
VT-3/150
Amplifier
is housed in a
machined
aluminum
case that ensures
optimum
RF
shielding, provides a good
ground,
and also acts as a heatsink.
Additionally,
the
VT-3/150
Amplifier
is equipped with output power and VSWR sensing lines
which can be
individually
configured as open
collector
or
linear
outputs. The
internal
VSWR
sensor protects the
amplifier
from high
antenna
VSWR by
approximately
halving the amplifier's
RF gain when a VSWR overload
condition
is present.
Output
filtering
for the
VT-3/150
Amplifier
is provided by the
VT-3/150
Lowpass
Filter
Board.
The lowpass
filter
assembly is mounted in a
separate
compartment
of the
amplifier
case in order to
provided
maximum
attenuation
of
harmonic
and other spurious signals.
Refer to Section 4 for the VT-3 132 - 174 MHz VHF
amplifier
and lowpass
filter
component
layouts and
schematic
diagrams
1.2
Performance Specification
Type: MT-3 series VHF
Amplifier
module.
Compatibility:
MT-3 series
Transmitter
Main
Board.
Frequency Range: 132 MHz to 150 MHz or 150 MHz to 174 MHz.
RF Power
Output:
adjustable
2.0 to 8.0 Watts
RF power Input:
nominal
level
adjustable
from +4 dBm to +10 dBm,
held within +/- 2 dB of nominal.
Ouput
Impedance
and
VSWR:
50 Ω, Type N
connector;
3:1 max. VSWR.
Input
/Output
Isolation:
> 60 dB
Duty
Cycle:
100%: Continuous
operation
from -40˚ C to
+60˚C.
Harmonic Emissions: Less than -80 dB
c
.