Furuno 851 MARK-2 - Manual (Page 7)

1-1
1. MOUNTING
1.1 Mounting Methods for Antenna Unit
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The antenna unit is generally installed either on top of the wheelhouse or on
the radar mast on a suitable platform. Locate the antenna unit where there is a
good all-round view. Any obstruction will cause shadow and blind sectors.
A mast for instance, with a diameter considerably less than the width of the
radiator, will cause only a small blind sector, but a horizontal spreader or
crosstrees in the same horizontal plane as the antenna unit would be a much
more serious obstruction; you would need to place the antenna unit well above
or below it.
•
It is rarely possible to place the antenna unit where a completely clear view in
all directions is available. Thus, you should determine the angular width and
relative bearing of any shadow sectors for their influence on the radar at the
first opportunity after fitting.
•
If you have a radio direction finder on your boat, locate its antenna clear of the
antenna unit to prevent interference to the direction finder. A separation of
more than two meters is recommended.
•
To lessen the chance of picking up electrical interference, avoid where possible
routing the signal cable near other onboard electrical equipment. Also avoid
running the cable in parallel with power cables.
•
A magnetic compass will be affected if placed too close to the antenna unit.
Observe the following compass safe distances to prevent deviation of a
magnetic compass: Standard compass, 1.00 m, Steering compass, 0.75 m.
•
Do not paint the radiator aperture, to ensure proper emission of the radar
waves.
•
When this radar is to be installed on larger vessels, consider the following
points:
! The signal cable run between the antenna and the display comes in lengths
of 10 m (standard), 15 m, 20 m and 30 m. Whatever length is used it must
be unbroken; namely, no splicing allowed.
! Deposits and fumes from a funnel or other exhaust vent can adversely
affect the aerial performance and hot gases may distort the radiator portion.
The antenna unit must not be mounted where the temperature is more than
70°C.