On Sat, 06 Dec 2003 17:32:58 -0800, Bill Turner
wrote:

Actually, one does come across such coils. All coils have a frequency
where they become a parallel resonant circuit, due to the capacitance
between windings. And oddly enough, *above* that parallel resonant
frequency, they become capacitive. Yes, you read that right, they
actually act like a capacitor, believe it or not.

Yes, I'm sure no one here disputes that coils behave like capacitors
above their SRF and capacitors behave like coils above the SRF. That's
not news. And it's to do with the *reactance* of the part, not its
inductance. AIUI, inductance is pretty much stable over the frequency
spectrum. You appear to be the only person here who claims otherwise.

Now, if you are always working with relatively small coils at relatively
low frequencies, you will probably never see this effect. But if you
ever have access to a $10,000 HP sweep impedance meter, hook up your
favorite coil and see just what I'm talking about. You will never look
at coils the same way again. :-)

That's *reactance* giving rise to that effect, not inductance!

--

"I expect history will be kind to me, since I intend to write it."
- Winston Churchill