How many has used them and on which cables do they go on. Can u tell a difference. Tks

first off.. your question is a little vague. There are more than one ferrite bead.. they are made up of a mix of materials that effect different frequencies. What they are used for is to suppress interference in all kinds of applications. I assume since you are posting on the TFF that you have an issue with interference from some source on your boat with your depth finders. I was getting interference from my trolling motor in my bow DF. I didn't have the power cable from HB that had the ferrite core in it. I bought the power cable with the core in it and it helped a lot. I tried to home brew by buying some ferrite cores and putting them in the original power cord I had but I didn't know the frequency of the interference, so they didn't work. My TM is a Motorguide Xi5 which is a motorized steering motor. I can't attach my transducer cable to the shaft of the TM because it has to slide through the steering motor to deploy. This turned out to be a good thing as it helps with the interference suppression as well. The further away from the TM the transducer cable is, the more suppression I get. I don't fish many grass lakes, so I don't have a problem with the cable catching on grass an causing issues. Long story short.. the right ferrite core will work but not just any ferrite core.

BD

I have used different ones and sometimes they don't help and moving the fish finder was the solution. If you go to the sub section of the forum that deals with accessories you will find lots of information and better help

Yes, I've got them on transducer lead at depth finder. Can't say it made noticeable difference.

Four of them came with my Garmin 106. Just wanting to
know if and where I should place them. Tks

My Echomap came with them as well, I haven't installed any and so far it seems to read fine. If I get livescope and I can't get the picture right, I might try one on the livescope transducer cable.

You stick them on the power cable plug, transducer cable plug and down by the LS transducer, (if you have one).