User's Manual Part 3

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be required it is recommended that a low loss coax such as RG-213 or RG-8 be
used.
It is recommended that the transceiver chassis is connected to ground using the bolt
on the rear panel to stop pick-up of unwanted noise from local power supplies and
electrical equipment.
Power Supply
All Barrett transceivers require a supply voltage of 13.8 VDC. In most vehicles or
vessels this is available from the battery, in the case of vehicles with a 24V system a
24V to 12V converter rated at 25 amps should be used (Barrett P/N 2090-06-02). In
fixed station installations where mains power between 88VAC and 256VAC is
available, a Barrett power supply (P/N 2090-06-01) should be used.
In base station installations where no mains supply is available a Barrett solar power
supply is available.
Note:- Some installations use an AC battery charger to float charge the supply
battery. Battery chargers can produce electrical noise from the rectifier diodes. This
noise causes a static type of interference in the receiver. It may be necessary,
therefore, to switch off the battery charger whilst the transceiver is in use. If float
charging of batteries is required for installations with unreliable AC power supply, it
is recommended that a Barrett power supply (P/N 2090-06-01) be used as this
provides a boost and float charge facility to maintain a battery without the noise
problem described above.
Voltage Drop
The average current consumption of the transceiver is low but during transmission of
voice peaks, high current is needed for short intervals. This means that the power
supply cable must be heavy enough to supply these short duration current peaks
without excessive voltage drop. Preferably use only the power cable supplied with
the transceiver. If extra cable is required use a cable with a conductor square area
of no less than 8mm. Unwanted voltage drop will also occur if incorrect wiring
techniques such as poor choice of connection points and incorrect use of terminal
lugs are used.
Protection Fuse
The transceiver is provided with adequate internal protection. However, the fitting of
an external fuse is considered necessary, not for protection of the transceiver itself,
but to ensure that in the event of damage to the cable, a fire risk does not exist. The
fuse used must be installed in the active wire as close as possible to the battery, and
must be of a type which has a low voltage drop at the peak currents expected.
Note:- in-line 3AG glass fuses are not suitable. An ATC automotive blade type
fuse rated at 25A with a suitable high current ATC fuse holder rated at 30A or more
should be used. These type of fuses and holders are contained in our standard
installation kit (Barrett P/N BCA20004) or are available individually (Barrett P/N
BCA20021)