fish finder interference

[b.gagnon]

Is there anything that can be done to stop the interference to a fish finder from a trolling motor? The motor is mounted at the front of the boat and the transducer at the back (12' boat), and run on separate batteries?

 

[cuzner]

Re: fish finder interference

Do you have ff on a totaly seperate wires going to your battery? If not that may be the easiest way solve your problem. I got lazy and wired to a common set of wires, worked fine with the motor off, but was useless when it was running. After I re-wired have not had a problem.<br /><br /> Jim

 

[Boatist]

Re: fish finder interference

If you have each unit on a seprate battery and the wires do not run close to each other then you can try fish finder on a LC power filter from radio shack or try a ferrite bead and wrap the + 12 volt line around the the ferrite bead several times near the fish finder. If the Fish finder is close to trolling motor control then move it away and see if it gets better. Most good fish finder try and sheild the electronic head to prevent external signals form affecting the fish finder and to stop the fish finder from interfeering with VHF Radio.

 

[waterone1@aol.com]

Re: fish finder interference

I gave someone the same advice a week or two ago about the noise filter...it didn't work for them. I still think this is a noise issue that is getting into the FF power line, but in the last case the standard radio shack noise filter did not work. I do not have a trolling motor on my boat, it would be helpful if there is a tech that has one to put a scope on it and see at what frequency the power supply is operating at. I am starting to think that the variable speed control of the trolling motor is much higher in frequency than a standard auto alternator (which the radio shack noise kit is tuned for).

 

[Boatist]

Re: fish finder interference

I think it is not power related at all. Since he is useing 2 seperate batteries and two seperate lines. Also I have seen many units run on the same battery and the transducer on the trolling motor and they work fine. Both units are running on 12 volt dc power supplies.<br /><br />My best guess is the interference is from the trolling motor control box useing a pulse power saving, and poor sheilding on the Fish finder head unit.<br /><br />Moving the foot control box away from the fish finder head would be a good start or moving the fish finder head away.<br /><br />Another thing that may be worth trying is running the trolling motor on full power and see if it gets better.

 

[kesso]

Re: fish finder interference

Can you describe the sort of 'Interference' that you are seeing?<br /><br />ie. Whole display (including text, numbers, FF reciever display(picture from transducer to ocean floor)); or is the interference limited to the FF receiver display only.<br /><br />Just trying to establish if its a Power or a Transmitter/Receiver interference problem.

 

[jimr]

Re: fish finder interference

I am the "other" problem i think Mine messes up with the TM on lower setting and when i turn it up it clears up. with mine the depth goes to the max. i seperated the wires and i guess i need to move the finder head it used to be up on top about 1 foot further away from the foot control for the TM. I am using it tomorrow night and will move it back to the top if it doesn't work out.

 

[Silvertip]

Re: fish finder interference

I have a 55PD on my boat with a PinPoint sonar transducer mounted on the motor. The motor, sonar, and marine radio are all fed interference free by the same battery. My stereo system does have a little interference from the Eagle sonar on the console but its located real close to the radio antenna. As someone else pointed out, I think there is a shielding problem with the locator.

 

[kence]

Re: fish finder interference

If your screen goes black when you are using the trolling motor at a lower power level and it works fine on full power, this is caused by the power modulation at the lower power levels and has been a problem with many trolling motors. I have never heard of a solution for this problem as it is caused by the way the lower speeds are attained.

 

[waterone1@aol.com]

Re: fish finder interference

From the above posts, I think we have eliminated the idea that the motor is inducing noice through the power lines to the fish finder. That would mean that the source is either the motor or the footswitch ( I don't know where the switch mode power supply board is located)and is being transmitted through the air to either the fish finder head or to the transducer or transducer wiring. I doubt if any of us has any lead sheets or screen grid laying around.....so ( I know this sounds cheezy) how about wraping the back and sides of the fish finder in aluminum foil and attaching a ground wire to it....just for a trial to see if it makes a difference.

 

[Boatist]

Re: fish finder interference

I agree sounds like problems are coming form the battery saver pulse circuits in the trolling motor control box. See if can move units farther away. If the trolling motor control box has a metal outer cover try attaching a heavy braided ground wire back to the battery. Try and add any type of sheild to both units.