98-175666-A
Appendix E: Grounding and RF protection
E-3
Grounding Recommendations
contact to the hull. Use serrated washers when securing the mounting bolts and seal the
joint with protective coating to avoid corrosion.
It is always recommended to establish the shortest possible grounding path e.g. on steel
hulls the ADU should be grounded directly to the hull
3
. However, due to the fact that this is
not possible on e.g. fiberglass hulls (nor is it preferable on aluminium hulls) a number of
alternative grounding methods are suggested in the following paragraphs.
E.2.3 Alternative grounding for steel 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.
To ground the BDU
The BDU should preferably be grounded to the ship with the short cable. Further, the BDU
must be grounded at its grounding stud in order to ensure a proper grounding if the short
ADU cable is disconnected.
The ground connection can be established either at the hull (recommended) or at a
dedicated RF ground if available (alternative).
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.
Figure E-2: Grounding the ADU
Note
For optimum grounding use the mounting bolt located closest
to the ADU cable plate, see
3. Please note that the ADU ground connection is made at the same electrical ground
potential as the BDU.
Antenna bottom
Mounting base
M12 bolt
Serrated washer
(stainless steel)
(stainless steel)
Important
However, bear in mind that the ADU ground connection
is to be made at the
same electrical ground
potential as the BDU
