KVH Industries TracPhone F55, Installation Manual

Page: 136 / 157

Appendix G: Grounding and RF protection
114 Alternative grounding for aluminum hulls
G.6 Alternative grounding for aluminum hulls
The following guidelines assume a two-wire, isolated grounding
arrangement; that is no part of the circuit, in particular the battery negative, is
connected to any ground potential or equipment.
G.6.1 Grounding the BDU
The BDU must be grounded by means of the Antenna Pigtail Cable and the
Grounding Kit (accessories, TT-403088A-930). Further, the BDU must be
grounded at its grounding stud in order to ensure a proper grounding if the
pigtail is disconnected.
The ground connection must be established at a dedicated RF ground (either
capacitive or electrical coupled). Bear in mind that the ADU ground connection
is to be made at the
same electrical ground potential as the BDU (see
Grounding the ADU ).
The BDU provides galvanic isolation (as required) from its input power
terminals to the chassis/grounding stud. This way the isolated grounding
arrangement is maintained.
G.6.2 Grounding the ADU
If the mounting base of the antenna is electrically connected to the hull (or
any other ground potential than the BDU), the ADU must be isolated at its
mounting bolts by means of shoulder bushes and washers - see page 123. This
is done in order to prevent DC currents flowing in the hull thus causing
electrolytic corrosion.
However, a ground connection must be established via one of the mounting
bolts using a separate ground cable. The ground cable must be routed parallel
and in close proximity to the shielded coax cable hence connecting the ADU to
the BDU Grounding Kit. A tinned heavy gauge wire (min. 6 mm
2
) can be used
for this purpose - see page 115.