Toroid choke adventure

Snap on Choke

A few weeks ago I was on my radio and once again I experienced some RFI issues with my PC and my morse code key. On my PC the mouse was moving all over the screen and the morse code key when using it I had extra dots and dits being sent. I use snap on chokes but I have seen in the past the chokes have become unsnapped and the choke is not able to do its job 100%. After my mouse and morse code key issues I move my radio desk out to look behind and have a look at the installed chokes. I was not surprised to see a number of chokes that were unsnapped. It was time for me to take this issue head on and solve it once and for all. I decided to put toroid chokes on each end of each
Not sure if this is normal
cable. I also decided to wrap each snap on toroid chock with zip-ties, I re-wound each toroid nice and tight and added the zip-ties to secure them. I am happy to say it has solved my RFI issue for over 3 weeks. I did have a question, I did notice on a few of my snap on chokes the cores had some markings on them. I am not sure if this is normal or if there was an issue with the cores?
Mike Weir, VE9KK, is a regular contributor to and writes from New Brunswick, Canada. Contact him at [email protected].

8 Responses to “Toroid choke adventure”

  • Bill KI7HYI:

    True toroid chokes cannot become unsnapped.

  • Clint, VE3CMQ:

    Hi Mike,

    I have never seen snap on chokes used this way before, but if it works, it works!

  • Mike VE9KK:

    Good evening Bill, yup it’s true the real deal will not unsnapped but I’m on a budget and these babies do the trick. I have the zip ties on hand so I put them to use. Thanks for taking the time to stop by Bill.

  • Mike VE9KK:

    Good evening Clint nice to hear from you, I got these chokes from Radio World in Toronto and the instructions with them shows this as one of the ways to wind it……..less the zip tie that is.
    Have a good week Clint

  • Kyle N4NSS:

    Part of the reason you have RFI is because either you station is too close to the antenna. It might even be your antenna. Your feed line is radiating because it is part of the antenna. You might also install a line isolator into the feed line.
    Tri putting it either close to the antenna or close to the rig.

  • Mike ve9kk:

    Good evening Kyle and thanks for stopping by, it is very true the antenna is very close to the shack but that is due to the fact that I have a small lot. The antenna I am using is an Endfed antenna so I do have a 1:1 balun from Balun designs but the only band that caused the issues the most is 40m. I have to keep my output down to about 40 watts along with the chokes I am good to go.
    Thanks for the input Kyle have a good what is left of the week.

  • Duane Cook NL7X:

    Hi Mike,
    My guess is the markings on the core chock materials refer to the permeability of the material. Your vendor may be able to help. But, it’s working for what you need, so adding or removing turns to tune the chokes may be futile?

  • Mike VE9KK:

    Good afternoon Duane and thanks for taking the time to leave a comment, I was thinking the same but it was the only 2 cores out of about 15 that were like that. I will drop them an email along with some pictures and see what they think.
    73 and have a great upcoming weekend.

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