Appendix C: Grounding and RF protection
TT-98-129218-A
Alternative grounding for aluminum hulls
62
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.
Grounding the terminal
The terminal must be grounded with the short antenna cable and the 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.
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 bushes and washers - see page 67. 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 62.
Alternative grounding for aluminum hulls
Antenna
Terminal
Heavy Gauge Wire
RF Ground
(Capacitive OR
seperate ground plate)
-
+
Terminal Grounding Kit
