User's Manual

AIS Class B Transceiver

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.