On 11/2/2010 1:07 PM, Howard Lester wrote:
> Jim, are you referring to the number of turns required as a function of the
> operating frequency?
I'm referring both to the winding instructions and also the various
discussions of how RFI occurs and how to kill it.
> And yes, the Amidon ferrites I bought long ago were FT-240's.
They are NOT Amidon ferrites, they are Fair-Rite toroids, with a VERY
high markup added by Amidon. AND the cores you bought from Amidon are
almost certainly not #31. The wholesale cost of these cores is about
$4 in lots of 100 or more. Last I heard, Amidon and other ham vendors
were selling them for something like $15. Not a fair price.
Appendix One of that tutorial includes advice about how and where to buy
ferrites and which ones to buy.
73, Jim K9YC
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