[TowerTalk] Choke on feed point of dipole

[Tom Hellem]

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