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BARRETT PRC-4090 TACTICAL HF SDR TRANSCEIVER - INSTALLATION
Marine Installations
The Barrett 911 automatic antenna tuner is designed for use in land base station
and maritime HF services. Primarily designed for operation with end-fed unbal-
anced antennas such as whips and long wires, the tuner is built in a waterproof
impact resistant, moulded ABS plastic enclosure.
Antenna Selection
The 911 automatic antenna tuner will operate into almost any end-fed antenna
with a length exceeding 2.5 metres, providing an effective ground (earth) is
used. The antenna efficiency will be proportional to the length of the antenna
and will be maximum when the length of the antenna approaches ¼ wave-
length. It is advisable to limit the wire antenna to ¼ or ¾ wavelength at the
highest frequency to be used.
Antenna
On sailing vessels the antenna can either be an insulated backstay or a whip
antenna mounted vertically, usually on the stern. Best performance will be
achieved by using an insulated backstay as the radiating length will be longer
than that available when using a whip. The top insulator on the backstay should
be approximately 300 mm from the mast and the bottom insulator should be
at eye level above the deck. The distance between insulators should be greater
than 10 metres and less than 35 metres. A whip antenna is generally used on
small to medium sized power vessels. There are different length whips to suit
the vessel length.
Transceiver and Tuner Mounting
Select a suitable position in the vessel to mount the transceiver. It should be a
position that is out of the weather and easily accessible to the operator, whilst
as close as practical to the 13.8 V DC power source. Mount the transceiver to a
solid fixing point using the mounting cradle. Make sure there is sufficient space
at the rear of the transceiver to connect the power and antenna cables.
The antenna tuner should be mounted as close to the antenna feed point as
possible. In metal vessels the length of the feeder from the antenna tuner to
the feed-through insulator, inside the vessel, should be kept less than 1 metre.
The antenna feed cable should be a suitable high voltage cable. Care should
be taken to avoid sharp points when terminating the cable to prevent corona
discharges.
The interconnect cable supplied with the antenna tuner should be routed away
from other cables back to the transceiver and connected as indicated in the
diagram on page 182.
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