RF ground..

[POINTER94]

Boats out of the barn and the work begins. Ah the exploration of a new to me boat. <br /><br />I am 3/4 of the way finished mounting my new depth finder but I have come across something that confuses me a bit. The power cable includes a bare unshielded wire for a RF ground. I have a power strip in the console and a grounding strip with plenty of open terminals but I don't want to do this twice.<br /><br />Where do I run the RF ground? To the grounding plate or to someplace away from electrical interferance? And in a 25ft boat where might that be?

 

[Boatist]

Re: RF ground..

Pointer94<br /> I never seen a RF Ground on a depth finder but it is a good idea. A true RF Ground would be a large braided wire with very fine wire. Like the braid on the outside of a coax cable. In the Large Mainframe computer business every thing is grounded with RF Grounds. We use a braided tube like a very large coax sheild. It is large enough to put your thum inside. <br />Best grounds on a boat, I/O engine block, Grounding plate, Battery Negitive cable.<br /><br />I have a 1985 Lowrance depth finder and when it was very new found it was getting RF out of depthfinder that interfeered with VHF channel 72. I wrote Lowrance and they said that they were aware of the problem and were working on a fix. They said they would notify me when found a cure. After 3 months I gave them a call and then they said never herd of that problem. I offered to send a copy of the letter they sent me telling what they were trying to fix the problem, but they did not want a copy of there support persons letter.<br />This is where I lost all respect for Lowrance products and there support. The support person said in his letter they were adding a RF ground wire, coating the inside of the plastic case with a metal/conductive paint, but that they were pretty sure the screen it self was the main source of the RF radiation.

 

[ThomWV]

Re: RF ground..

All models of depth finder made by Furuno have a static ground. Its not an RF ground, as you'd find used to establish a ground plane for a radio receiver, its just there to disapate the potential caused by static. Very few folks connect them to anything at all and most of the folks who do hook them up do more damage than good because they connect them directly to an engine mount. That provides a direct link to any stray currents caused by bad spark plug wires, bad alternators, and a host of other electrical gremlins that might be found in the motor.<br /><br />If you do decide to connect it to something you could go directly to a metal thru hull but even this is to be avoided if your boat has a bonding system. The best bet is to use something like a Dynaplate (a small plate that attaches to the bottom that is made from sintered (sp?) bronze made just for this purpose). <br /><br />The real point is that unless you find the depth finder has a lot of strange little blips and streaks on the screen, particularly if you find that they flicker, the thing really isn't needed. In fact even in those cases you will almost always be better off by filtering the power supply, something you can do for about $6 with a DC power conditioner straight from you local Radio Shack.<br /><br />That help any?<br /><br />Thom

 

[POINTER94]

Re: RF ground..

Boatist and Thom,<br /><br />Thanks guys. I arrived at the decision that unless interferance in an issue I would not hook it up. If it does, I think I will run it to the new brass through-hull I am installing for the washdown system..<br /><br />The unit is a Raymarine, fishfinder..... Got me wondering if they too have a problem Boatist otherwise why add it????

 

[ThomWV]

Re: RF ground..

Gosh, I hope this doesn't make a lot of people mad.<br /><br />No, its not an indication that you have a second rate fish finder. Actually its an indication that you have moved up from second rate fish finders. Now don't get me wrong, I'm no fan of <br />Raymarine fish finders (though I love their radars), but its a better fish finder than a lot of the ones on the market.<br /><br />Thom

 

[POINTER94]

Re: RF ground..

Thom,<br /><br />No offense taken in the first place, and the greatest fish finder in the world wouldn't help my fishing prowess. <br /><br />But I have been a fan of Raytheon/Apelco products since I was a kid. I know there are probably better brands but I have had nothing but good luck with the product offerings from them and some bad luck with some of the favorite brands mentioned here. (Eagle, Lowrance, Garmin)<br /><br />I installed an acetal plate (1/2")on the transom to allow me mounting flexability and additional equipement without drilling new holes or more than the four needed to secure the plate. Adjustments are far easier....<br /><br />Kind of tough to offend me, and thanks again for the information..

 

[Boatist]

Re: RF ground..

Pointer<br />Just interested if your fish finder has a zoom greater than 4 times?

 

[POINTER94]

Re: RF ground..

Yep,<br />x2, x4, x6, x8

 

[Boatist]

Re: RF ground..

Pointer<br />That times 8 will be a big help if you fish deep water. Bottom lock or bottom track also very good for deep water.