Parts List

Table Of Contents
VHF Amplifier Instruction Manual VT-3 132 - 174 MHz
3-1
3
VT-3/150 AMPLIFIER ALIGNMENT
3.1
General
Connections to the power
supply,
alarm
and
transmit
enable
lines
(ENA),
are
clearly
marked on the
amplifier
case. The
amplifier
is
enabled
when the
enable
line (ENA) is grounded.
If the
amplifier
is
installed
in the
transmitter,
alignment
is
simplified
by using an SR-3
Subrack,
SM-3 System
Monitor,
and RF
extender
cable
to
provide
transmitter
power and signal
interconnection
(see the
Transmitter
Main Board Manual for
details).
For
complete
transmitter
alignment,
the
Transmitter
Main
Board,
Synthesizer,
Amplifier,
and Audio Processor should be
tuned in the
aforementioned
order. Please refer the corresponding manuals for each module.
If the input RF
level
is not chan
ged,
adjustments
to the output power and
alarm
thresholds may be
made
without
removing
the
amplifier
cover.
However,
in the case of a
complete amplifier
alignment,
the
amplifier
should be
separated
from the
Transmitter
Main Board and the
amplifier
cover
re
moved
to expose all
amplifier
circuitry.
All
jumpers and test points are
clearly
marked.
3.2 Repair Note
The
VT-3/150
Amplifier
is
mainly
made up of surface mount
devices
which
should not be
removed
or
replaced
using an ordinary soldering iron.
Removal
and
replacement
of surface mount
components should be performed only
with
specifically
designed surface mount rework and repair
stations
complete
with
ElectroStatic
Dissipative
(ESD)
protection.
When
removing
Surface Mount Solder Jumpers, it is
recommende
d to use solder braid in
place
of
manual
vacuum
type desoldering tools when
removing
jumpers. This
will
help
prevent
damage
to
the
circuitboards.
3.3 Recommended Test Equipment List
Alignment
of the
transmitter
requires the
following
test
equipment
or its
equivalent.
Dual Power Supply:
Regulated
+9.5
Vdc at 0.1 A.
Regulated
+13.8
Vdc at 2 A -
Topward
TPS-4000
Oscilloscope /
Multimeter:
Fluke 97
Scopemeter
Current Meter: Fluke 75
multimeter
Radio
communications
test set : Marconi Instruments 2955R
VSWR 3:1
mismatch
load:
JFW
50T-035-3.0:1
coaxial
test
cable
set three 50 cables of
incremental
length 20 to 40 cm
Alignment
Tool:
Johanson 4192