On 7/31/2012 4:13 PM, W0UCE wrote:
> One aspect of the K2AV FCP is KISS. However, experimenting with change of
> components and proven architecture should anyone opt to do so will produce
> unfavorable results.
Jack,
"It seems to work good in the places it's been tried" but has never been
compared in a disciplined manner to something of known performance is
hardly "proven architecture." Guy has done some excellent engineering
here, and published it. Now he's getting some serious peer review, with
suggestions for possible variations on his work. That's how the "state
of the art" progresses. From where I sit, it appears that the most
important aspects of his design are the compact dimensions and the field
cancellation in the dirt, not the transformer.
As an example of this peer review process, Rudy Severns, N6LF, published
some excellent and disciplined work several years ago on his
measurements of slightly elevated radial systems for a 40M vertical.
That work showed that, on 40M, four radials elevated only a foot or two
were nearly equivalent to many long radials on the ground (he set up
those and many other conditions and MEASURED the field strength).
When I tried to scale his hypothesis to 160M (that is, multiply the
radial heights by a factor of 4x) on an antenna I had built, I could not
duplicate his result -- that is, the gain of the antenna was at least
3dB less than I had expected. I discussed this over dinner this spring
with Tom Schiller, N6BT, who has also done a lot of work with radials
and verticals for 160M. He observed that you can't simply scale the
radial height by the difference in wavelength because "the earth is very
different at 160M as compared to 40M, and the radials must be much
higher." When I asked him "how high," he suggested 16 ft. This summer,
with a lot of help from W6GJB, I got them up to at least 16 ft for most
of their length, and preliminary testing suggests that I'm now getting
the gain I had hoped. When I've got more performance data, I'll publish
it.
Peer review is a wonderful thing. It is an important part of the
scientific method. I've learned a lot by publishing what I think I know
and having folks fill in my weak spots.
73, Jim K9YC
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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