Furuno FELCOM251, Installation Manual

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2. INSTALLING THE SYSTEM
2-7
2.2.4 Antenna Unit mast design
Overview
The antenna mast must be designed to carry the weight of the antenna unit, which is
approximately.
• 23 kg for FB-1501 (also add the weight of the mast flange) for the FELCOM501 An-
tenna Unit and
• 3.9 kg (also add 1.1 kg for the mast mount kit) for the FELCOM251 Antenna Unit.
The mast must also be able to withstand onboard vibrations and wind forces up to 108
knots on the radome, even in icing conditions.
The FELCOM501 and FELCOM251 Antenna Units use different methods for mast
mounting. The following sections describe the methods separately.
FELCOM501 Antenna Unit mast flange for FB-1501
1. The top of the FELCOM501 An-
tenna Unit mast for FB-1501
should be fitted with a flange
with holes matching the bush-
ings in the radome. The flange
thickness must be at least 10
mm.
2. Place the supplied insulation
sheets between the flange and
the antenna unit.
3. Drill a hole in the center of the
flange for the antenna cable.
4. Connect the pig-tail cable as-
sembly (NP0.5NJ-SN5DFB) to
the base of the antenna unit.
5. Connect the pig-tail assembly to
the antenna cable.
6. Waterproof the coaxial cable with self-bonding tape.
7. Mount the antenna on the flange with four M10

35 hex. head bolts. The length of
the bolts must be such that they engage into the bushings of the radome with min-
imum 10 mm and maximum 25 mm.
8. Apply marine sealant to the exposed bolts.
9. Protect the cable connection against water ingress by wrapping it with self-amal-
gamating rubber.
For recommended dimensions of the flange, see the outline drawing at the end of this
manual.
Important: Avoid sharp edges where the flange is in direct contact with the radome.
Round all edges as much as possible to avoid damaging the surface of the radome.
Insulation sheets Insulation sheets