AIS Class B Transceiver
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As the range of VHF signals are governed by line of sight, the antenna should
be placed as high as possible, while remaining clear of any metallic objects.
Long whip antennae are generally recommended for larger boats, although the
most popular antennae for marine use is 1m (3ft 3in) long. On sailboats these
are usually mounted on the masthead, where the length of the antenna keeps it
clear from the navigation lights and wind vanes. This type of antenna can also
be mounted on the cockpit roof or powerboat garages.
For maximum range, it is recommended that a VHF antenna specifically
tuned for use with an AIS is used, and mounted away from the standard
VHF antenna. Vertical separation is preferred, but where this is not
practical, at least 5 metre horizontal spacing is recommended
WARNING
The antenna coaxial cable and any connectors used must
be rated at 50Ω. Under no circumstances should standard
domestic TV cable and connectors be used. Incorrectly
rated cabling and connectors could result in power not
reaching the antenna, but also power could be reflected
back into the AI50 unit, damaging it in the process.
The quality of any connections and integrity of the cable will directly affect
the performance of the radio. Poor soldering or corrosion of the terminals
can impair performance. We recommend that screw or crimp terminal
type connectors are not used for any through deck fittings - a good quality
waterproof solder terminal connector will be less susceptible to poor
connection due to corrosion of the contacts.
To ensure the best performance of the radio, the antenna cable should be
routed where it is least likely to interfere with, or receive interference
from other electronic equipment, such as echo sounder transducer cables
and high current carrying cables.
The antenna cable should terminate in a standard marine PL259 plug
fitting. Connect the antenna plug to the socket on the back of the AI50
and screw the retaining collar down Fig. 2.3.
Note To avoid possible water damage to the transceiver, it is recommended that all
cables are looped to provide a drip path.