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I am trying to wind an rf choke for the W1FB Crystal Evaluator "A TEster for Crystal F, Q, and R" in the January 1990 QST. The parts list specifies 15 turns of #26awg magnet wire for 850 uh. I did not have any #26 but had some #24awg. In using the Mini Ring calculator it says to use 53 turns of #30awg.
When I measured my 15 turn rf choke on the specified FT37-43 toroid I get about 115uh which is a far cry from the 850uh specified in the parts list.
What am I missing?
Not sure about anything else, but...
15 turns and 115 uH sounds about right for a FT37-43 core.
73, Diz, W8DIZ
As it turns out, the parts list was telling me that the mu of the FT37-43 is 850u so it was not supposed to be 850uh but 850u. I was also told on the Homebrew list that your toroid calculator on your web site said that 15 turns should be about 80uh not the 115uh that I experienced. As it turns out it does not make much difference anyway as this is an rf choke application.