On Mon, 11 May 2009 16:28:04 -0700, "Tom Donaly"
wrote:

Hi Richard,
In point of fact, I just used a dip-meter-frequency-counter
combination to see if I could get somewhere near the results that
ON4AA's calculator suggested.

Hi Tom,

I wouldn't have expected any other method based on your "tease."
It answers the need for lightly coupling which responds to your
admonition of not presenting disturbances to the measurement. About
the only variation to this would be in how you could lighten up the
coupling further. I don't see Cecil struggling for the low fruit
here, so I'm not expecting to see him make this into a rum punch.

Later, I cut the coil at its center point,
attached a cheap antenna analyzer there and looked for a frequency of
least impedance. The dip meter indicated about 8.93 Mhz and the analyzer
indicated 8.98 Mhz. I consider the closeness of the two readings to be
pure accident.

Pursuing an alternative method helps validate them both, another
hallmark of good bench work. That Steve finds two values that
correlate through software begs the question of what parameters were
used. As such, two in silicon against two at the bench - something's
got to give. The differences are not deep in the decimal places.

However, they do reinforce each other in leading me to
believe that the Corum calculator has some serious deficiencies. Serious
enough, that those who claim its correctness should do some practical
investigation into its merits in order to spare themselves the jibes of
their more analytical brethren.

Tom subscribes to Corum (if I read his posts correctly), to the extent
of his needs. That seems sufficient for me, but it does not attach a
proof to the conjectures and it doesn't serve the glaring points by
the authors that their model works only with resonating coils (if I am
reading them correctly), or unless you derive your own M factor (no
one stepping up to the plate for that suggests they have no deep
interest in the topic). They allow roughly 10% error as it stands,
and I observe debates trying to leverage 5% positions.

73's
Richard Clark, KB7QHC