Cheap led lights

   / Cheap led lights #11  
Be advised, snap on ferrites are not all equal. They come in different mixes. And when you buy them off of Amazon or E-bay, the sellers do not tell you what mix it is. Probably because they don't know. The various "mixes" from mix 31 to mix 77 on have varying degees of "chocking" effectiveness depending on the frequency of operation. So what might work good at FM radio (88 to 108 Mhz) might be totally ineffective at lower frequencies like the AM broadcast band (530 to 1710 khz). I have drawers full of ferrites with different mixes, and many I got off of Amazon and ebay with totally unknown mixes. I have solved many many RFI problems with them. But they aren't all the same, and not all the same effectiveness.

Also don't forget you can often solve radiation problems from a device by putting a good ceramic capacitor, say .01 microfarad with a voltage rating significantly above the input voltage across the input voltage line (differential mode) or from each side of the line to ground (common mode) This will also often provide relief. Not near as easy as a snap on choke, but it is an option for those that know what they are doing with a soldering iron.

I had a heck of a time with my 100 watt 3.5 MHZ signal getting into my alarm system. Tried lots of "unmarked" snap on ferrites on the leads, to no avail, but fixed it with a simple .01 600 volt capacitor across the power supply lead going into the alarm box. Yeah of course I am not afraid to make modifications to an alarm box. I grew up with a soldering iron in my hand, and have worked as a tech for decades. But if you are going to be "into" a technical hobby, you need to have some technical skills.

If you have a choice in mixes (you can buy ferrites with known parameters from Digi-key or Mouser electronics), probably a mix 31 would be your best bet. Yes this is a very technical subject.
Ferrite Mix Selection - Palomar Engineers(R)

What would I do?. I would go to my parts box and get a .01 cap and throw that across the power line up near as the lights as I could get it. then weather proof the connection. Or I could take some snap on and throw it around the feedline and see what happened. It is easy to try it. But I have drawers full of these things and I am willing to bet most of you don't.
 
   / Cheap led lights #12  
The shorter the cable the better.. Yes caps work as well.. Some people install ferrites in an easy to get to location and they don't completely eliminate interference.. I got lucky with my install in my brother 7710, I put two of them near the lights and whalla, no more interference..
 
   / Cheap led lights #13  
Also another "good to know" fact is the more turns of the cable you can get to pass thru the core of the ferrite the higher the choking effectiveness will be. As an example if you can only pass the cable thru the core the one time, it may or may not be effective, but if you can pass it thru 2 times it will have 4 times the effectiveness. The effectiveness accrues at the square of the number of turns. Three turns thru would be 9 times.
 
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  • Thread Starter
#14  
Great responses. To be specific, snap on for the radio power?
 
   / Cheap led lights #15  
   / Cheap led lights #16  
Of course the larger and better quality the more they cost. Some of the best ones are made by a company called FairRite. They are kind of an industry standard. Japanese manufactures make them as well like TDK and they have a good name. You may remember them from making cassette tapes years ago. There are a lot of cheap Chinese with no ratings and no information of any kind about them. They are the "pig in a poke" variety. I have a drawer full of those before I learned better. Yes, I am not a know it all, but I am getting smarter every day. :)

Index - Fair Rite

I have dealt with this distributer, and he seems to be good to deal with. You might note that he is a ham too.

Ferrite Products for RF Chokes, Baluns, and RFI Mitigation
 
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  • Thread Starter
#17  
If my dad was still around, he'd have the answers for me, he was also a ham. The switch panel is in the headliner, might be able to do both ft and rear with one snap.
 
   / Cheap led lights #18  
For those who are visual learners, this short video will help you understand how to use Ferrite to mitigate RFI.

 
   / Cheap led lights #19  
Know this: Chasing down RFI issues is not all milk and cookies. Yeah sometimes, a snap on or two and you'r done!. That is great, but it doesn't always work out that way. Sometimes multiple things must be done. Results can be additive. One here, one there, two over there, Gotta do them all to get rid of the problem. Sometimes. What I am saying, is just because you did something, does not always mean all of your problems will be over. Patience and perseverance is key.

And if and when you do get the problem solved, is when you sit down and start to think: "why didn't the silly bastich of an engineer design in these things to begin with?". "Why all of a sudden is this my problem to solve?"

Good question indeed!. And you know the answer..
 
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