KVH Industries FB250, Installation Manual

Page: 174 / 202

Appendix C: Grounding and RF protection
Alternative grounding for aluminum hulls 161
CCCC
Gr
ounding
and
RF
C.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.
C.6.1 Grounding the terminal
The terminal must be grounded with the short antenna cable and a grounding
kit. Further, the terminal must be grounded at its grounding stud to ensure a
proper grounding if the short antenna cable is disconnected.
The ground connection must be established at a dedicated RF ground (either
capacitively or electrically coupled). Remember to make the antenna ground
connection at the
same electrical ground potential
as the terminal (see
Grounding the antenna ).
The terminal provides galvanic isolation (as required) from its input power
terminals to the chassis/grounding stud. This way the isolated grounding
arrangement is maintained.
C.6.2 Grounding the antenna
If the mounting base of the antenna is electrically connected to the hull (or
any other ground potential than the terminal), the antenna must be isolated at
its mounting bolts by means of shoulder bushings and washers - see
page 169. 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
antenna to the terminal Grounding kit. A tinned heavy gauge wire (min. 6
mm
2
) can be used for this purpose - see page 162.