# Fish finder interference



## Nussy (Jun 26, 2011)

I just got a new pontoon boat and put a 48v electric Parsun motor on it. I wired up the rest of my 12 v stuff to one of the batteries in the series. It all works fine, but my HB 798 c si isn't working right. It has all kinds of interference. If I turn off the 48 v it works just fine. But if even the key is on, there's horrible interference. You guys have any ideas?


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## shawnfish (Jun 26, 2011)

run the 798 to its own battery and keep the transducer cable away from any other wires and the engine and you should be good to go....


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## TNtroller (Jun 27, 2011)

+1 on the seperate battery, a small lawn mower batt will power it for a day or 2 before charging in most cases.


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## fender66 (Jun 27, 2011)

I had the same problem with a HB unit. There is a noise filter setting on it also. I can't remember...might have to turn on the "advanced" option to get to it, but it's in the menu. The different battery might solve it though. If this is a new unit...I recommend registering it on the HB site and calling them about it. Apparently, there are lots of issues with all the units that they don't tell you about unless you call them. (Lowrance has the same deal). When you call, do so early when they first open as there is usually a wait.

Make sure your software is up to date too. It's a free download from HB site (after you register I think ???).

They actually have sent me a new transducer cable and transducer on separate occasions due to problems I've had. Works fine now though.

PM me if you need help finding anything that I've mentioned.


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## FuzzyGrub (Jun 27, 2011)

A small seperate battery would help isolate the issue. If it doesn't clear it up, the noise is most likely being picked up on the transducer, or possibly your external gps. Seperating them as far as possible from the elec outboard and its wiring, is the next thing to try. 

Call HB and make sure you send them info on that elec outboard. They could easily assume it is a "normal" elec trolling motor. They use to send out a "interferance kit", but it might not work on that elec outboard.


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## Nussy (Jun 27, 2011)

Thanks for the input guys. I put it on a small battery and it works fine. I'll have to give HB a call to get ther recommendation. I'd like to keep it on the main batteries if possible since they are on inboard chargers.


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## fender66 (Jun 27, 2011)

Nussy said:


> Thanks for the input guys. I put it on a small battery and it works fine. I'll have to give HB a call to get ther recommendation. I'd like to keep it on the main batteries if possible since they are on inboard chargers.



Good news, but sounds like it's not completely solved yet. So...is this a new unit? They have been good in supporting me with both of mine (actually only one had an issue). They also told me that it is common for interference to happen with the trolling motors that have "digital" features. They specifically mentioned Min Kota too. I have a Motorguide but it does say it has digital monitoring to avoid overheating. I don't think the "digital" was an issue with mine though. My issue was solved with a new transducer. They actually had this same problem with many of the same units and I had to wait for them to redesign, test and make a special transducer for it. Once that was installed (by the way..it was free except for my frustration for 2 months of waiting), the problem was solved. They have even followed up with me to make sure all is well. I'm pretty impressed so far.


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## FuzzyGrub (Jun 28, 2011)

Check to make sure you have the right power cord. The one you should have, has a noise filter choke in it. It is about the diameter of a quarter. Also, if you didn't have it hooked to the 1st battery in the series of four, try that. Otherwise, whatever HB recommends.


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## shawnfish (Jul 3, 2011)

my old 798ci SI HD had the problem until i ran it off its own battery and even then sometimes it would act up,they sent me the trolling motor interferance kit and it still worked the same. come to find out i have a set of wires ran through one of my gunwales for a light and my nav. light and once i removed it i never had an issue. also humminbird did contact me once every week or two to make sure i had no problems and they sent me a bunch of stickers(and minn kota) and some HB patches, i thought it was pretty cool to keep contact with me and make sure i was happy and then the free stuff...best there is, hands down...........


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## Hanr3 (Jul 4, 2011)

The reason teh seperate battery works is because you have seperate wiring.
Run new wire from the Fishfinder to the batteries and that WILL take care of your problem. The interference your getting is no doubt fromt eh negative side. Beting the fishfinder and trolling motor share the negative wire, hence the interference. Run a seperate wrie and taht interfrence will go away. Both wires have to be connected to the battery posts.


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## Nussy (Jul 5, 2011)

Hanr3 said:


> The reason teh seperate battery works is because you have seperate wiring.
> Run new wire from the Fishfinder to the batteries and that WILL take care of your problem. The interference your getting is no doubt fromt eh negative side. Beting the fishfinder and trolling motor share the negative wire, hence the interference. Run a seperate wrie and taht interfrence will go away. Both wires have to be connected to the battery posts.



The are actually wired separately already. The motor has it's own wire going directly from the transom to the batteries. Only probably 6 feet total. All the other 12 v stuff I have run together. Not much in total...radio, nav lights, horn, courtesy lights. Decided just to go with a small battery that I Already have for ice fishing.... Thanks for the ideas, I think I will try to get HB to send the interference kit and try that.


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## krawler (Jul 10, 2011)

Your trolling motor is putting out RF interference which is very common. You can contact the manufacture for a noise kit or build you own. It's basically snap on ferrite chokes which can be purchased at "Radio Shack" or online.

https://www.radioshack.com/product/index.jsp?productId=3012599
https://www.radioshack.com/product/index.jsp?productId=2103222

Simply snap these on the wires close to the unit. You need one on the trolling motor and one on the fish finder.

I had the same problem with my boat, noisy trolling motor causing interference on the fish finder, VHF and radio. I put 5 of these on my boat including one on the main wire harness just before the switch panel. Everything is very quiet now, running the trolling motor and or the outboard with no interference at all.


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## fender66 (Jul 10, 2011)

> I put 5 of these on my boat including one on the main wire harness just before the switch panel.



Why 5? Won't one one the troller and one on the FF do it?


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## krawler (Jul 10, 2011)

Maybe call it overkill but I put one on my radio, VHF, fish finder, power wire to switch panel and trolling motor. Everything is quiet, no noise from trolling motor or the gas outboard. I turned the fish finder noise filter off and still no interference. Before the snap chokes, the fish finder would have weird lines and large thin arches all over the screen.


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## fender66 (Jul 11, 2011)

krawler said:


> Maybe call it overkill but I put one on my radio, VHF, fish finder, power wire to switch panel and trolling motor. Everything is quiet, no noise from trolling motor or the gas outboard. I turned the fish finder noise filter off and still no interference. Before the snap chokes, the fish finder would have weird lines and large thin arches all over the screen.



Good info...thanks.

You shared 2 "choke" links with us. Which one did YOU use?


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## krawler (Jul 11, 2011)

Different size chokes for different sizes of wire.




The largest just fit on the trolling motor






The small one's fit the fish finder and Vhf radio.


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