SG-231 MANUAL
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
© 11/00 SGC, Inc.
P.O. Box 3526, 98009 Fax: (425) 746-6384 Tel: (425) 746-6310
E-Mail: [email protected] Website: www.sgcworld.com
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5.3.1 Vehicle Grounds
Connect the coupler directly to the frame of the vehicle. Ensure that a heavy strap is
used from the coupler ground lug and that the connections are cleared of all paint and
dirt so that the shiny metal is exposed. SGC always recommends that two grounding
bolts with star washers be used to ensure no ground resistance is encountered. Make
sure that the grounding point is not insulated from other parts of the vehicle by non-
metallic couplings, bushings, fiberglass panels, etc. Modern vehicle assembly
techniques that use spot welding may not always adequately connect various body
parts. Use an ohmmeter and insure your vehicle is electrically bonded.
Another area to watch is trunk lids and hoods. Because many body parts are dip
painted, they may float above the RF ground when assembled. Use of short heavy
braid to insure all doors and hatches are grounded is good installation practice.
Although this is tedious work, the benefit is that once completed you will have a much
superior radiated signal and lower noise floor on receive.
5.3.2 Marine Grounds
A metal hull vessel in salt water provides an almost ideal ground. The coupler should
be connected directly to the hull using the shortest possible ground strap or 2 to 3 inch
wide 2 mil copper foil. Make sure that the contact point is free from paint and dirt.
Ensure a good contact area for minimum resistance.
Wooden and fiberglass hulled vessels present more of a grounding problem. It is
normally necessary to bond all large metallic parts such as the stove, fuel tanks, engine,
and propeller shaft; sometimes an external grounding plate should be connected to the
hull. The bonding and grounding plate should be chosen with consideration for the
problems of electrolysis. Severe damage may result if dissimilar metals are connected
together.
Our experience is that sacrificial zinc's, which double as radio grounds, may help, but
are not by themselves a complete solution. If you use one (or more) of these devices,
remember to provide for a large physical counterpoise in addition.
In a sailboat installation, we generally place the Smartuner in the aft lazaret and then
run at least three runs of foil forward. One runs up the port chine, just below the
waterline, another up the starboard chine below the waterline, and the third up the
center of the vessel.
The center foil is generally connected to the rudderpost, transmission, engine, and keel
bolts. The chine foils are attached to through hulls, the stove, tankage and so forth. The
idea is to get as much metal inside the vessel connected as possible. Metal toe rails and
lifelines work well as do keel coolers on motorized craft.
Here is a tip for attaching foil to keel bolts. When a large keel bolt is exposed, drill into
the keel bolt and tap the hole for a suitable stainless steel machine screw. Attach with
suitable copper washers for a solid electrical connection.