On Thu,4/16/2015 12:30 AM, Rick - DJ0IP / NJ0IP wrote:
To all of you guys commenting on the common mode current of an OCFD, I have
one simple question:
Several years ago, I modeled a 40M OFCD dipole with offsets varying from
a foot increments of a few feet to a lot more, and dissipation in a
practical choke inline with these antennas. The results are not pretty.
Looking late at night (it's 1 AM here), I can't find the pdf showing it,
but the bottom line is that you don't have to go very far off center
(5-10%) to have enough common mode to fry a really beefy choke when
running high power. High power is defined as 1-1.5 kW. You may, of
course, be luckier at 100 W.
Your mileage will vary ONLY to the extent that you run lower power
and/or lower duty cycles and/or a feed that is less off-center. We are
stuck with the laws of physics.
73, Jim K9YC
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