Codan Radio Communications VT-3-150-SN User Manual
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.
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 changed, 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 removed
to expose all amplifier circuitry. All jumpers and test points are clearly marked.
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 removed
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.
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 recommended to use solder braid in place of
manual vacuum type desoldering tools when removing jumpers. This will help prevent damage to
the circuitboards.
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
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
Ω
cables of incremental length 20 to 40 cm
Alignment Tool:
Johanson 4192