Re: TC Resonance and Topload Measurements

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-uswest-dot-net>" <davep-at-quik-dot-com>


>         After checking my setup, I tracked the 60Hz issue
> down to an impedance mismatch issue.  In actuality,
> the function generator output was being attenuated down
> to about 20mVpp at 60Hz, so of course there was no output!
> (something about 50 ohms driving 0.100ohms ... go figure!)

	Errrr.  Is the function generator output really 50 ohms?
	It may be, but read on...

	It's not uncommon (I've been fooled by) that a generator
	will be marked as '50 ohms' and actually have a quite
	different, even non constant impedance...  The usual logic,
	if the manuals are dug into is that the output is rated
	to _drive_ 50 ohms, at the _rated_ voltage.  The actual
	impedance may be something entirely other...

	Roughly:
		Measure no load output.
		Load with 50 ohms.  (or whatever...)
			REmeasure output.

	If the second reading is half the first, then indeed the
	internal impedance is   50 Ohms.  If not, some basic
	ohms law will yield the inernal impedance.  Handy
	to check this at a couple of other frequencies of interest..

	best
	dwp