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Upgrading Electronics - Where is my ground?

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SamR

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Dumb question. My new GPS/Sounder should be connected to a ground. Where would I find one on my 1800?
 

DaleH

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They're meaning "earth ground". Less having one already installed, which usually means having a large "Dynaplate" installed on the hull, most people leave them [earth grounds] off.



A Dynaplate is a large piece of sintered bronze affixed to the outside of the hull, in full contact with the water, used to (1) reduce RF interference and (2) offer the best path for hull bonding, i.e., reduce/eliminate electrolysis and galvanic corrosion due to the electrical differential between dissimilar metals.

Whereas the intent is to have a "clear path to ground", if you end up with severe "noise", e.g., vertical lines or other clutter, on your GPS/sounder unit (I highly doubt you will have any ...) you could also add a clear single-run ground wire from the unit's earth ground post and straight back to the battery. From my experience with OB-powered boats, you'll be fine. Also make sure you check your GPS/sounder operation when your VHF mic is keyed to transmit.

There are other methods available to preventing/minimizing stray RF that could otherwise cause interference ... you can add ferrites to the sounder leads or twist the power/ground leads going to the unit, at least a few (2-3) twists per inch is what's usually recommended. Note this does limit the usable length of the "existing" unit's power leads.
 

JWL

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There are two simple ways to ground your GPS. You can run a ground wire from the unit to the battery or an easy way to run a ground from the unit to a ground of the power block. I have my GPS run from the power block to the GPS and back to the negative of the power bloc. Be sure to have an in line fuse for the GPS unit.
 

SamR

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DaleH":4ak5h9t6 said:
you could also add a clear single-run ground wire from the unit's earth ground post and straight back to the battery. From my experience with OB-powered boats, you'll be fine.
Thanks Dale as always :) Would you mind spelling this out for me though Dale. 101 version for a non gearhead :oops:
 

DaleH

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SamR":h4k308tb said:
DaleH":h4k308tb said:
you could also add a clear single-run ground wire from the unit's earth ground post and straight back to the battery.
Would you mind spelling this out for me though Dale. 101 version for a non-gearhead ...
Try in this order ...

1) First off, try the unit as is with the power (12+) and ground (12-) taken from whatever power/ground busses/strips you already have up at your existing helm station, i.e., those that power/ground everything else up there. 99% of the people doing such don't have any noise/RF issues.

2) When some have noise issues when connecting to the power source(s) at the helm, separation (VHF from GPS/sounder) of wires and/or the twisting of the power/ground leads usually solves most/all of it.

3) If you still get serious stray noise, put a dedicated earth ground lead (I'd use green or black wire) from the unit's earth ground terminal and run it through your wire chase and connect to the negative post of your battery.

4) Or, I have some spare ferrites you could install ...
 

SamR

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That clears it up for me Dale, thanks. I'll post pics of the set-up once I get the rest of my parts in.
 

Hard Core

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I installed a Weather Fax on my Furuno system, and couldn't get any reception without the earth ground. I ran a heavy gauge cable to a thru-hull. Granted not as good as a dyna-plate, but got the job done without putting more stuff on the hull.

You won't need to worry about this for GPS, but for SSB reception a stable ground plane is critical.

The black bus in your console is not an earth ground, that is on a current carrying path back to your batteries/engines (negative side). The earth ground is designed to be a dedicated path to the water that does not carry any current. It is DC electrically the same thing, but very different for high frequency stuff that is depending on that ground plane being stable for signal reception.
 

pelagic2530

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hey dale, im experiencing one of those problems that you highlighted. my sounder shows a line for the time that the radio is transmitting. what causes this, and what might i do about it? thanks :D
 
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