Re: Model T First Light

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Dave -

Tesla list wrote:

> Original poster: "David Kyle by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dave-at-kyleusa-dot-com>
>
> Hi Bart,
>
> Thank you for the feedback. I had not made the connection regarding a
> helix primary diameter and Coupling Coefficient but of course now that
> you mention it, it is so obvious. I am kicking myself for not seeing
> that before. This is a learn as you go hobby and it sure helps to have a
> few masters around to show the way.

No master here. Just a coiler like many others.

> I have been reading up on theory in the archives, what a treasure trove,
> and I came across some posts regarding optimal Coupling Coefficient (k).
> As I understand it between 0.15 - 0.28 k is considered optimal although
> it is possible to operate outside those values and many do. Are these
> values still considered the norm?

Yes. This is the typical window for K on classic helical coils. Maggy's run
higher and the
latest flat coil may also run higher (meaning, it may be possible to run
higher K without ill
effects). I'm not sure if all coilers maximize coupling however. I do know
that when coilers
make the leap to actually measure K and report numbers, they are usually
familiar enough to
also adjust height for maximum K, so this window is probably pretty good to
go by.

> So then I jump to what value would favor a small coil and what might
> favor a larger one. Logically I would infer a smaller coil might benefit
> from a higher k since it needs maximal energy transfer and being low
> power is less likely to be plagued with racing arcs and other symptoms
> of over coupling. Where as a larger coil with a big power supply might
> require a smaller k to avoid the pitfalls of over coupling. What part
> might the coils frequency play in this?

Just the opposite. Larger coils tend to run at higher K's than smaller
coils. I'm not sure why.
I could theorize, but won't. I will say that there are "a lot" of
parameters involved.

> All, please feel free to comment if I have this all wrong.
>
> Dave
>
> =========================================
> Dave Kyle
> Austin, TX USA
> Email: dave-at-kyleusa-dot-com