Go to
then scroll WAY down to
"The easiest way to identify most ferrite materials is to wind about four turns of wire through the core and then measure the lowest frequency at which the value of reactive impedance equal resistive impedance i.e. X=R. There will be some variation between different batches and sizes of materials. But if you can plot the results graphically you can easily identify the 'signature' of each material.
Here are my references for some common ferrite materials
FT240-77 0.74MHz
FT240-31 3.5MHz
FT100-33 7MHz
FT240-43 17MHz
FT240-K 22MHz
FT240-52 31MHz
FT240-61 58MHz"
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and
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and this page is long, but might also help ('way down the page)
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And there's
"Name that Core" by Carl Luetzelschwab K9LA"
(a 2-page document for which I have no URL, just a printout of the text, with a graph and a chart.
OR this might work:
}
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You can also look back at this group's topic 72777666 for some more tips.
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Doug, K8RFT
