John-
I'm doing exactly that.
But The horizontal portion of my feedline as it leads away from
the vertical dipole is not exactly horizontal, it drops down
at maybe a 30 degree angle for about 8' , then it drops
straight down vertically to the ground.
I am getting the feeling this could be part or all of the problem.
Tom
K0SN
On Mon, Jan 12, 2026 at 4:42 PM <john@kk9a.com> wrote:
> I'm not quite sure what you're doing. If I were building a simple
> vertical
> dipole I would feed it in the middle with coax and put a choke on the coax
> near the feedpoint, then I would run the coax horizontally to get it away
> from the vertical.
>
> John KK9A
>
>
> Tom Hellem K0SN wrote:
>
> TT'ers:
>
> I made a choke to place at the feed point of a 20 meter vertical dipole.
> 9 turns of #14 thhn wound on a 2.4" mix 31 ferrite toroid.
> After I installed the choke, the resonant frequency appears to have
> moved approx. 1 mhz lower.
>
> Is this the behavior I should be seeing?
> I've used plenty of chokes on yagis, etc and never noticed this
> before.
>
> Modeling in Eznec shows that changing the ground constants
> does not appreciably change the resonance, so it seems that the fact the
> ground getting wetter between the two measurements would not
> be the cause.
>
> Any ideas?
>
> Tom
> K0SN
>
>
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