View Full Version : interference transducer on trolling motor
I have a problem and can't take it any more. I have a variable speed bow mount 24v motor guide and I mount my Vexilar transducer to the trolling motor but at higher gain settings I get a lot of interference when I run the trolling motor. Apparently the electomagnetic field in the variable speed motor (as compared to the 5 speed models) causes the interference. I have tried running a ground from the shaft of the trolling motor to the negative terminal of the cranking battery and it seemed to cut the interference a bit but not nearly good enough. HELP?
Thanks.
EconGuy
10-01-2002, 08:15 PM
Brad,
Do you have your negative post grounded to the hull? I had a similar problem and grounding to the hull eliminated the problem.
EconGuy
EconGuy,
I have not grounded the negative post to the hull. How do I do it?
I have a Crestliner if owning a metal boat makes any difference. And thanks for the fast response!
Johnnie Candle
10-02-2002, 06:11 AM
Try a noise filter. These are available at Radio Shack and are very inexpensive. They filter the electrical noise from everything in the boat. I will have one for every piece of electronics on next year's boat for sure. They work Great.
EconGuy
10-02-2002, 07:19 AM
Brad,
I not sure how the Crestliner battery compartment is set up(I have a Lund). If you can find a rib or any metal piece that attaches to the hull a small metal screw is all you need to attach the ground wire. Good luck!
EconGuy
Jigging 5
10-02-2002, 08:04 AM
I think you have a ground loop problem. All grounds tied together and connected to one common ground is the best way to correct this problem. Ground loop = When two or more electrical devices have multiple paths to ground this is a ground loop condition. This develops potential or voltages which can cause interferance,noise and can cause damage. Hope this helps.
Erie Adict
10-02-2002, 09:47 AM
I am the guy who several weeks ago had interference problems with the Minkota and the x-85. Here is what I have tried with no success.
1, Radio shack filters, On power lead and Transducer Lead
2, Connected the grounds of all the batteries (2 trolling, 1 Cranking) together. This gave no improvement. In Fact, When the trolling motor was turned on, I would get loud interference through the stereo. diconected common ground
3, Ground all of the batteries to the hull. No improvement. See previous post about galvonic carorsion (sp?) disconnected
4, Tried a seperate transducer from lowrance mounted on the trolling motor, but with the wire ran as far away from the trolling motor as I could get it. Some improvement. But not a long term fix.
Have tried to contact Minkota several times to no avail.
Open to any Ideas.
I contacted Vexilar today about the interference problem. Got through right away I might add. The technician said to try connecting the ground of the cranking battery to the negative post on the battery that the negative trolling motor lead is attached to ( I have two batteries for 24v). I will try that and hopefully see how it works this weekend. This sounds like the ground loop solution that Jigging 5 is referring to?
Thanks.
Steve KS
10-03-2002, 09:51 AM
Here is another suggestion. It sounds like the interference is getting picked up in the signal wire between the transducer and the locator. Try wrapping as much of the transducer wire as you can in aluminum foil to provide a shield for the transducer cable. Most signal cables are shielded internally for noise reduction (coaxial TV cable has a shield like this). Try to wrap the aluminum foil around the transducer and between the transducer and the trolling motor housing. Don't wrap the foil over the sending end of the puck. Try to use one continuous piece of foil to cover everything. I don't know if the vexilar cable is shielded or not. Attach a temporary ground wire to the aluminum foil. Now try the trolling motor and locator and see if the noise is reduced. Granted this sounds pretty goofy but if it works you can find a way to construct a permanent shield around the cable and at least you know how to stop the noise and you have it isolated to one cable.
Paul H
10-03-2002, 01:13 PM
Might also temp rig up something and see how far away from the motor you have to move the transducer before or if it quits picking up the noise. I know there are seperate mounts to mount the xducer rather than just hose clamp it on - maybe a few inches farther away will help.
aplcory
10-03-2002, 02:01 PM
A simple solution for this is to place a thin piece of lead between your transducer and trolling motor. that will fix your problem.
Lots of options to try and I appreciate the input.
Erie Addict-were the Radio Shack filters you installed called toroid chokes? From the on-line illustration it appears that you wrap your power cable around this thing and the transducer cable around another choke and somehow this zaps the interference out of the system?
Since the interference is caused by the stronger than normal electromagnetic field emitted by the motor guide I think sliding a piece of lead between the transducer and motor guide housing makes a lot of sense. After all-lead is used against protection against x-rays. Now, where are those duck decoy weights? Actually, I think the weight off one of my marker buoys will work.
Thanks