James Meyer wrote:
. . .
And how do you know for sure that calculations overestimate Q when
measuring Q to verify the calculations disturbs the very thing you're measuring?

An engineer knows when to say "close enough". A mathematician is never
satisfied.


I've measured quite a number of inductors both with a homebrew setup, in
which I account for the losses in the input and output networks, and
with an HP Q meter of specified accuracy. With simple input and output
networks consisting of a small series C and shunt R, the effect on Q is
predictable and easy to calculate. Results from the two methods agree
quite closely, even though they use somewhat different methods to arrive
at the Q, giving a fair amount of confidence in both results. And both
disagree quite dramatically in some cases to Q calculated simply from
theoretical calculations which include only conductor resistance
(including skin effect, of course), inductance, and shunt capacitance.
This is with inductors of only moderate Q -- calculation of very high Q
inductors, which is being discussed here, would require more attention
to second order effects -- as would measurement.

Thanks for the profound observation about mathematicians and engineers.
In which category does one put a person who's satisfied with
calculations made without thinking about, caring about, or considering
the errors caused by ignoring fundamental effects? Certainly not an
engineer as I use the term.

Roy Lewallen, W7EL