Jim wrote: So the apparent change in L as the turns are expanded or compressed is simply the CIRCUIT resonance moving as the stray capacitance changes. For all practical purposes, L does NOT change. C changes.
-------------------------------- The inductance measurement method I used does not rely upon a resonant frequency of any sort. It measures the inductance by differentiating a square wave. The frequencies involved do span the RF spectrum, of course, since the waveform used to test the inductance is a square wave. A square wave is made up of the fundamental and a very large number of harmonics, all added together. The validity of the inductance measurement using this method is borne out by noting that the inductance value reported is that at which the inductor can be used to form a resonant circuit at the desired operating frequency within the normal range for the core material. That is, for a core designed for HF, a measured 3.1 uH resonates properly at HF (e.g. 3.1 uh in parallel with 47 pf resonates at about 13 MHz). Ron AC7AC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
