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Where is the RF ground point?

Old 08-27-2014, 06:14 AM
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Default Where is the RF ground point?

I am installing a Raymarine a67 MF GPS in my 2005 Chaparral Sunesta 274. In addition to the positive and negative lead leads in the power cable there is an RF (drain) wire. The instructions say to attach it to the boat's RF ground point. I don't know where that is.

The positive and negative buss bars are easily accessible under the helm station. Can the ground wire be tied into the negative buss on a boat or is there a separate point that ties in elsewhere?
Old 08-27-2014, 06:31 AM
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Technically (and hopefully) the negative buss is grounded to the motor, and the motor is properly grounded to saltwater. This is assuming all the connections were made properly and haven't corroded. The RF ground point should be to one point on the motor with saltwater contact. So, yes, ground it to the negative buss. But make sure you have a clean path to water.

On boats with SSB radios, they will have a ground-plane plate in direct contact with the water. Your Ray system is not the application for that type of marine grounding.
Old 08-27-2014, 06:55 AM
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The recommendation from Raymarine is to connect RF ground directly to the negative battery terminal using a relatively thick wire for boats without dedicated RF ground plate mounted on the outside of the hull.
Old 08-27-2014, 07:07 AM
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Thanks a million. The electrical system is very clean (no corrosion) and I was able to follow the wiring back to the engine compartment.

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