NorthStar Navigation GM1708 961XD - Manual (Page 34)

SECTION TWO - Installation
Page 24 961 INSTALLATION MANUAL Revision A
Figure 16: Correct AN150 and 8410 wiring
RF grounding
The grounding system is an equal partner with the antenna in producing
quality differential beacon signals for the 961 differential receiver. Lack of
proper grounding can adversely affect differential signal strength, as well
as SNRs, and is the most common source of problems with differential
antenna installations. The same grounding techniques that have worked
well for loran systems will work equally well for differential antenna sys-
tems. Essentially, the ground system provides a secure connection to a
large electrical mass; ideally, the earth itself. On a vessel, this means
establishing electrical contact with “seawater” ground. On a steel vessel, a
good connection to the hull or steel pilothouse is sufficient. Wood or
fiberglass vessels require a metal ground plate or a thru-hull fitting. If the
metal ground plate is impractical, the engine block or the negative (–)
battery terminal can sometimes be used, but only as a last choice due to
stray electrical noise that may be present at these locations.
NOTE:
This connection must be made before the ACU is screwed into
its base.