k0ua
Epic Contributor
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.
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.