[TowerTalk] BigIR question

Jim Brown jim at audiosystemsgroup.com
Thu Dec 7 15:01:54 EST 2017

On 12/7/2017 11:23 AM, David Robbins wrote:
>>> Air core coils are of questionable value as common mode chokes, for
> reasons I articulated in k9yc.com/RFI-Ham.pdf
>>> The better solution is a ferrite core choke with balls. :)
> Air core is better than cracked ferrites and melted coax in those little pvc
> cans!!
That's not what I suggested.
> And can be done quickly with materials at hand without having to
> worry about getting enough ferrite mass to handle whatever burned up those
> supposed 3kw rated 'baluns'.

Read the tutorial, David. A coil of coax that doesn't burn up is a good 
thing, but it should also work as a choke. A coil of coax may or may not 
work, depending on the rest of the common mode circuit. By "work" I mean 
killing the common mode current on the coax that fills in the nulls of 
the pattern and couples RX noise.

73, Jim K9YC

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