Topic: 998SI TM Interference

[Rmax]

My front mounted 998 SI won’t work with Minkota 101 Fortrex TW in operation.  Noise filters are on high had a choke installed this week but it didn’t help with the side imaging. 

Also, how fast do you have to go to get the down imaging to work on the trolling motor.

Rmax   

[RGecy]

Rmax,

Welcome to the forum.  You can get excellent images at 1mph, you will just need to adjust your chart speed down to maybe 1 or 2.  Also remember to get the best images, you will need to keep a fairly straight line.

As for the TM Interference, did you get the kit from Humminbird?  Do you have the unit running on the same battery?  It would help to isolate if possible.

Here is a recent topic on it?  http://forums.sideimagingsoft.com/index.php?topic=75.msg10743;topicseen#new

Good Luck,

Robert

[Rmax]

Thanks Robert.

They only installed the HB Choke from the Minkota Trolling Motor foot control.  I see that there's also a Choke that can be installed on the power cable as well.  Should I assume that I need this as well?

This is a new 998 SI so I assume that it already has the correct transducer but wonder how I can tell the difference to verify.

When you say isolate, do you mean that I need to run a wire straight from the battery to the 998?  This isn't as easy because Legend Boats fill every void space with foam, making it impossible to fish wires.  Trolling motor is on a seperate set of batteries than unit and the drivers dash 998 works perfect.  I still have a lot to learn but getting the corrrect set up is my 1st proirity.

I really appreciate the help because I spent a a lot of $$ to set up 998 SI's from and back to maximize results on a new Alpha 211.


Rmax

[Wayne P.]

Historically, the Minn Kotas have less TM interference issues than the Motor Guides. Have you checked the grounding wire fuse in the motor head?

[Rmax]

Yes, it was checked out by Allstar trolling motor repair when they installed the Choke.

[Wayne P.]

Check that fuse yourself and verify that it is OK and its connection is OK. Any further remedy attempts are more radical.
The interference is RF (radio frequency) and is caused by the motor variable speed electronics ( most of the time) there are no absolutes with that issue.

Your unit should already have the PC 11 power cord with the built-in choke. That choke is about 3/4" thick and 1 1/4" round, located 4" from the unit plug.

If you have Interlink, disconnect it for a while. That is just an antenna for the RF until you get it figured out.

There are a few "grounding" methods that may work sometimes when the previously mentioned motor internal ground wire doesn't.

Try putting a jumper wire (any size) between the negative of the battery you are using for unit power (starting battery ?) and the battery negative that your trolling motor negative wire (black) is hooked to.  Don't connect it anywhere other than those two places. No NOT hook it to any of the other trolling motor batteries anywhere !!!!!! That is called a ground loop.
Report the results--there are a few more remedies available that may or may not work.
Let me know via e-mail so the suggestion turn around time will be less (well maybe not tomorrow, I'll be on the water with my 1198 trying to find some fish, LOL)
purdum43@aol.com

Also post a picture of the TM choke installation.

I spent 6 months dealing with that same issue with a Motor Guide.