Kevin,
I'll risk further criticism of AIM measurements and point you to some
charts on my web site which might make things clearer:
http://www.karinya.net/g3txq/chokes/
Notice how narrow-band the resistive portions (black bands) are of the
#61 designs, and bear in mind the earlier discussion about SRF
measurement uncertainty with narrow-band chokes, and you can see that
#31 or #43 material is a much safer option.
73,
Steve G3TXQ
Kevin Normoyle wrote:
> This is all great and thanks for taking the time to go thru it yet one
> more time.
> Even though I've read the papers, it's great to see the give and take of
> slightly different points of view for really getting a grip on what all
> the key issues are.
>
> So looking at Fair Rite #61, 13 turns on 2.4" o.d core, seems primarily
> resistive above 14Mhz.
>
> Assuming I'm just thinking about the 20M/15M/10M bands, 13 turns of
> RG303 on a double stack of #61 seems to meet the desired goals?
>
> Am I wrong there?
>
> But then, if our measurement capabilities are better for below 14mhz,
> and I can be confident of the inductive reactance I get from #61 at the
> lower frequencies (and knowing whether there are resonances there)...why
> can't the same double stack be good for <14 mhz?
>
> I guess I'm wondering if the justification for "resistive impedance is
> better" is being taken from one frequency range and being applied to all
> frequency ranges...unnecessarily implying #43 (or #31) is better than #61
>
> ?? I may just be trying to summarize something that can't be summarized.
>
> Seems like some of the issue is trying to have one thing cover the range
> of 1-30mhz which is too hard. And our inability to measure well, for
> over 10mhz.
>
> I also can't help but think that using more turns of narrower RG303 thru
> a core is better for controlling stray capacitance, therefore creating
> more repeatable results...especially important if I know I can't trust
> the measurements of what I build.
> ???
> -kevin
> AD6Z
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