# Trolling Motor Transducer interference



## Maisch4077

Im looking for suggestions on eliminating interference Im getting on my bow mounted Lowrance HDS 8 Gen 2. It has to be partially due to the trolling motor because i get blue lines on the screen when the trolling motor blade is running and they disappear when I take my foot off. The crazy thing is I also have an HDS 5, First Generation on the bow and no interefence shows on that screen. I have two transducers mounted to the trolling motor and have tried switching on both units. The HDS 5 shows no interference, the HDS 8 Gen 2 lights up with blue lines when I run the trolling motor. Any suggestions would be appreciated?


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## crappiedude

I have and HDS 7 & 8 gen 1 and a Mtorguide Tour TM. I had quite a bit of interference from the TM and eliminated most of it by wrapping my TM wires 2x around 2 RF chokes. I added the chokes near the TM plug. See Radio Shack catalog # 273-104 this is a 2 pack so I just used them both.

I found lot of ueful info on another web site. I'm crappiemax over there.

http://www.crappie.com/crappie/fishing-electronics-trolling-motors/196928-rf-interference.html

Getting rid of the interference isn't that hard but some times just figuring what causes it can be tough. 1 thing I did find out was that not everything worked the same for everyone. I by no means am an electronics genious so anyone can do it.
If you have any questions I'll be glad to help anyway I can, just ask.


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## Fishman2025

Make sure the fishfinder is wired direct to your main battery. Not your trolling motor batteries or to accessory connections on boat. Also make sure the wired run a different route then the tripping motor power wires. This fixes a lot of issues. 

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## Maisch4077

After reading your comments and the additional info on that crappie website, I realized the issue maybe the location of the power cable for my HDS 8. Its on a RAM mount and the power cable comes out of the floor from under the RAM mount which is close the the in floor mounted foot control for the trolling motor. The HDS 5 that works fine in mounted down in-dash in the bow and further away from the trolling motor foot control. I'll try relocating the power cable for the HDS 8 first and go from there. Thanks!


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## crappiedude

Are you running a transducer on your TM?
My problems started when I added a 2d ducer to the TM. They ended when I added the RF chokes. My original intent was to only share info from the rear ducers via ethernet and LSS-1. I then disconneced the ducer and found I still had interference. I tried additional grounds to the TM and it did nothing. I added smaller RF chockes to the powerlines going to the head unit (HDS7) and it didn't help at all.
Someone somewhere posted those RF cokes I originally posted and it seemed to do the best job so far. If I get a chance I'll try to post a pic later.


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## Maisch4077

I have two transducers on the bottom of my trolling motor. One ran to my HDS 5, the other to my HDS 8 Gen2. The HDS 5 is merely a backup unit that I have rigged up in case the transducer on on the bigger unit goes out. I fish for Erie smallmouth a lot and its not uncommon to have a transducer go out on you. I have no interference on the HDS 5, its only on the HDS 8 Gen2. Ive even switched the transducer cables on the units and its still only the 8 that has the interference. The power cable to the HDS 8 comes out of the floor underneath the mount its on which is pretty close to the trolling motor foot control so Im thinking that is where my interference is coming from. Im going to mess with it this weekend. I'll try taking some pics and uploading them too.


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## crappiedude

Now, I am jealous...Lake Erie smallies. My unit almost made me crazy. I thought, I'm going back to my old Silent 60 flasher for the front DF and just use the ducers for the HDS units on the back.
I like having the GPS and DI on the bow. I switch between having the 7 or the 8 up front. Most of the time, who ever is in the back of the boat don't really know what they are looking at anyway.


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## Silver Fox

The TM foot switch and the related cabling can be very noisy electrically. In my experience its best to keep the fish finder power cables and the units themselves at least 8 to 12 inches away from the foot pedal or the control cable that goes to the TM. I know in some cases this is not possible, but I think you will find that providing as much separation as possible between these components will help reduce in reducing the interference. The power line chokes, TM grounding and battery wiring also are part of the solution but as pointed out, every boat will be slightly different depending upon hull type and how it is actually wired. Unfortuneately, there is no magic bullet solution just elbow grease persistance and a methodical application of potential fixes yields results.


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## Maisch4077

I tried moving the power cable away from the TM foot control on saturday but still getting interference on the screen. Whats crazy is that the interference only shows up on the HDS 8 Gen2 on the bow. I have an HDS 5 also on the bow and it shows absolutely no interference.


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## crappiedude

Do you have a ducer on the trolling motor?
The Gen 2 is probably even more sensitive than the Gen 1.
I forgot about the pics on my RF chokes, I'll try and add tonight. Best thing I did.


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## Silver Fox

If the cable separation is there then I would certainly try installing toroid chokes or something simular. Make sure the choke is installed on the power cable as close to the back of the unit as possible and get at least two full turns of the wiring wrapped through the center of the choke. The more turns, the better. Also check the menu settings for interferance rejection and make sure that they are enabled. If you have done any unit resets, the software defaults for some of these units is to have them turned off.


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## crappiedude

You have to excuse the poor quality of the pics. i used my cruddy phone ca,era and the boat was in the garage but you should be able to get the idea.

Here's a pic of #273-104 chokes wrapped around the TM power cords. This is what really made the difference for my unit.









This next pic is where I used another type of rf choke #273-105 and I wrapped it around the hot wire going to the HDS plug. Actually (again) I used 2 chokes. You can not actually see the choke in this pic because they are wrapped in electric tape. This is what Silver Fox is refering to. This had no effect on my unit. If I were to do it again, I would use the #273-104 and wrap both the hot and ground wires around the choke(s) as many times as possible. As noted earlier all these units are different so it may work for you.










Here's the results









Here is one other option I saw awhile back over on BBC (Bass Boat Central) 
http://store.humminbird.com/products/323062/TMC_1 
A lot of Low guys have had good success with this. It was going to be my next step. Just don't tell the Bird guys you had to use it to fix a Low problem LOL

Keep us posted.


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