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Thread: Ferrite Rod Balun

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  1. #1
    Join Date
    Oct 2010
    Location
    Antrim, N Ireland, UK
    Posts
    177

    Default Ferrite Rod Balun

    Hi all, I have a Ferrite rod diameter 8mm and 180mm length just wondering if this would make a good choke as I should be able to get a good lot of turns on it using RG58 any thoughts?

  2. #2
    Join Date
    Apr 2007
    Location
    Tyalgum, near Murwillumbah ,far north coast of NSW
    Posts
    128

    Default Maybe not rg58

    Gday Name?

    I not sure rg58 will stay healthy wound in such a small diameter.
    RG174 should work as it is a smaller diameter and can be wound in a small diameter. One catch is rg 174 is good up to about 100 w .Im not sure of the exact rating but a google search should give an answer. Also you may find in data sheets for the two coax ,they have minimum coiling diameters which should not be exceeded.
    I asked a similar question to yours on another thread and received no answer.
    I asked if anyone has tested a ferrite rod as a good hf balun core.
    I used one here wound with two enamel wires on my 40/80m single coax feed dipoles. I did get a little tvi due to coax being too close to the tv antenna.( 3ft)
    I doubled the distance from the tv antenna and the tvi disappeared. I only tx with 10w due to licence restrictions.
    This may mean the balun was still allowing common mode current down the feedline,or it may be other things at work.
    Unfortunately measuring balun effectiveness appears to be quite difficult.
    Have a look at the thread I started titled "balun measurements " and see what the experts have to say !?

    Brendan

    just did a quick google
    heres the data for belden 174
    http://www.belden.com/techdatas/metric/8216.pdf
    Max watt is 354 at 10mhz.
    minimum bend radius 25.4mm

    These guys have made some http://users.catchnet.com.au/~rjandu...n_winding.html
    enjoy
    Last edited by VK2FXXX; 02-16-2011 at 09:28 AM. Reason: added link and 174 rating

  3. #3
    Join Date
    Oct 2010
    Location
    Antrim, N Ireland, UK
    Posts
    177

    Default

    Thanks for the replies folks, I hear what your saying Brendan it does go very deep!
    I am using the "Ugly Balun" about 8 coils wrapped around a 6ins cutting of pipe and dont have any TVI. My aim is to get rid of the big circle hanging in the sky if you know what I mean.

  4. #4
    Join Date
    Apr 2007
    Location
    Tyalgum, near Murwillumbah ,far north coast of NSW
    Posts
    128

    Default

    Im back
    First have a look at this page http://www.karinya.net/g3txq/chokes/
    The black lines in the coloured bars are the bits you want to see.
    Notice also the ferrite materials on the right.
    Unfortunately no ferrite rod types. If your ferrite rod is a similar material to the listed toroids youre in luck,but we dont know what it is!

    You could try undoing your ugly balun and use no balun!
    Dont be scared.
    You may not need one at all. The one you have may not be effective anyway.Try it and see. If the tv plays up ,or you get rf problems in the shack ,without the ugly balun on ,then you probably need a balun.Then make one . Use your ferrite rod and copy the design in the link above. stick it at the feedpoint,if problems still exist with stray rf then that balun is probably not effective. Go back to the ugly one,and search for some proper hf balun ferrite material.
    A decent toroid should only cost about 10quid. Dont feel pressured to use a balun. People say its good engineering practice to use one,and it is.They are cheap for what they can do(home built). But find out if you need one first ,then design and build a good one from proven materials.
    That`s enough from me
    Enjoy yore balun adventure!
    Brendan

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