RE: Secondary Turn Spacing - Toroid Size

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Cameron B. Prince" <cplists@xxxxxxxxxx>

Hi,

Thank you and all the other members for their input on this subject. I will
drop the turn spacing idea and shoot for 1,500 turns. Are Dr. Resonance's
ideas compiled in a common place somewhere that I could look at?

I had some correspondence with Richard Hull and it seems my toroid is too
small (10x30), or my cap is too large (0.1uf). I want to keep my cap, so I
guess I'll either piggyback a larger toroid on top of the current one or
replace it with a really large one.

Thanks again for your help,
Cameron

> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Tuesday, May 31, 2005 8:23 PM
> To: tesla@xxxxxxxxxx
> Subject: Re: Secondary Turn Spacing
>
> Original poster: FIFTYGUY@xxxxxxx
>
> In a message dated 5/30/05 10:07:07 PM Eastern Daylight Time,
> tesla@xxxxxxxxxx writes:
> "I was considering using 17lb. test nylon fishing line to
> space the turns in an effort to minimize distributed capacity.
>
>      I borrowed a solenoid optimization spreadsheet that had
> been tweaked for TC secondaries, to determine the optimum
> configuration (lowest losses, least wire cost, etc.)
> Admittedly it was designed for the CW case (heat dissipation
> was a taken into account!), but it factored in every
> conceivable aspect of wire that I've ever seen.
>      Long story short, space winding is lossy for TC use. How
> lossy, and whether it's noticeable, depends on how
> drastically you space it. Others have already replied in this
> thread on the obvious tradeoffs.
>      It was interesting that least losses occurred near the
> point where the skin effect was equal to the DC resistance.
> By attempting to lower losses or increase inductance by
> changing one parameter, theoretical performance suffered
> because of the necessary change in another parameter.
>      FWIW, the spreadsheet predicted optimum results almost
> exactly along the lines of Dr. Resonance's longtime
> recommendations. However, dropping to 1000 turns only causes
> a 10% performance penalty with 33% wire/space/cost savings.
>      The optimum wire length values were near the 1/4
> wavelength value, but this was pretty much a
> consequence/coincidence of the boundaries. Dropping to 1000
> turns from the optimum 1500 range obviously works nearly as well.
> Not to mention that the theoretical optimum wire length
> diverged from the
> 1/4 wavelength as coil size increased.
>
> -Phil LaBudde
>
>