On Sun, 13 Aug 2006 15:02:03 +0100, "Reg Edwards"
wrote:


"Cecil Moore" wrote
Reg Edwards wrote:
A coil 6.6" long, 6" diameter, 26.5 turns, has L = 68 uH, Q = 500
at
3.8 MHz, and self-resonant frequency = 9 MHz.

Wouldn't mounting the coil four inches above a GMC pickup
ground plane reduce the Q and the self-resonant frequency?
--
======================================
Cec,

Very likely. But not very much.

It would not be the self-resonant frequency any more. The srf never
changes. And neither does the intrinsic coil Q.

We must be careful with our descriptions. Slackness leads to
misunderstandings, arguments and fights.
----
Reg

Reg, I had never given much thought to the series relationship of the
capacitance between turns. I had always considered them as being in parallel,
thus the honeycomb, or the basket-weave configurations to minimize the interturn
capacitance. Have I misconstrued the purpose of those configurations?

Do I also understand you correctly that with a specified length of the solenoid,
and a given diameter, the total interturn capacitance is independent of the
number of turns, because the capacitance between turns adds in series to the
same value regardless of the number of turns?

Please educate me.

Walt