Re: Toroid winding numbers and measurements

Chris Wilson

Hello Lee,

This is very true, I am experimenting with a new power amp and also
a big LPF bank for it. If I measure with a Fluke LCR mter that's still
in calibration it measures at (from memory) 100kHz. But if I use my
AIM4170 analyser I can measure inductance at the frequency the amp
will be run at, and the inductance value is somewhat different. This
variance is of course more marked the higher infrequency above the
Fluke test frequency the inductor under test will ACTUALLY see in use.
I suppose a spectrum analyser with a tracking generator would be a
better tool still for messing with them.

Wednesday, November 1, 2017

One last caveat:  The measured inductance will very with the
frequency used to measure the inductance.  Hans has not told us if
he just calculated it or if he measured the best inductance with
an instrument.  If he used an instrument we would have to know the
frequency used.  In other words if you remove or add turns to
acquire the exact inductance needed but did this at a different
frequency because your meter is on a different frequency, your
results will not be what is required.  In my estimation one is
playing with fire trying to match inductance without knowing the
standard's test parameters.  A lot of hams don't realize
inductance of an inductor changes with frequency.  An inductor
tested at one frequency will give a different inductance if tested at a different frequency.
Lee, w0vt


Best regards,
Chris mailto:chris@...
Best regards, Chris Wilson (2E0ILY)

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