Topband: Lazy question concerning toroidal inductors

[Richard (Rick) Karlquist]

Not enough information.  How many turns?  How much current
through inductor?  What core size?  What material?  Do you
already have a particular core you want to design around?
What Q do you need from the standpoint of antenna efficiency?
Is Q only a thermal issue?

As a VERY general rule, Q is somewhat higher with more turns, so you
would want to just use smaller wire and increase the number
of turns.  Books will not tell you this fact.  It's a second
order effect having to do with leakage inductance.
You should confirm it in your case by making comparative Q measurements.

Rick N6RK

On 8/6/2012 7:29 AM, Tod Olson wrote:
> I am sure [or at least I hope] I could sort through the information
> available in books and on the web for the answer to this question, but
> maybe someone reading this reflector can give me an 'instant' answer
> [preferably correct].
>
> I intend to use a powdered iron core toroid as the form for an inductor
> which will be used in a matching network at the base of a vertical. The
> wire size is #16. Since I have already fabricated and measured a couple of
> these inductors, I know the number of turns needed to get 5.5 uH. I need
> 11 uH so I put two in series and the expected 11 uH was measured at the
> frequency of interest.
>
> The question I pose is:
>
> Is it preferably to use two of these inductors in series or use two
> stacked cores and the requisite number of turns to get 11 uH? The expected
> current through the 11 uH  is about 3 amps if the Q is about 100. Will the
> Q be different if there are two inductors or one inductor made using two
> cores? [same size wire].
>
> All comments are welcome. Even suggestions about where to search the web
> for an answer or where to look in a book for the equations that will
> resolve this matter. Or suggestions on where this has already been
> discussed. Or suggestions on the steps to use to quickly get the answer.
>
> I suspect that this is part of the 'lore' that has been developed which is
> why I am asking the question rather than trying re-invent the solution
> using first principles.
>
> Tod, K0TO
>
>>
>
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