Re: 1/4 wave theory/cite the variance?

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

Original poster: "Metlicka Marc by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>

All,
One of the reasons that i wound the 3000 turn coil was to see if i could
notice any effects of winding a coil "over" the 1\4 wave of the wire.
  Using wintesla i wound the 8.75" coilform with roughly 7100' of 28g
wire to a length of 42.5", This using my 6" x 24" dtc-at-32.1pf topload
gives a 1\4 wave of 6843', 257' of wire over.
I wondered if the windings at the turning point of the wave would get
hot or anything, well it didn't.
It is entirely possible that the toroid not being totally smooth has
effected this "rough" experiment? I had planned on removing wire until
i could get right on the 1\4 wave, but it became a factor in the tssp so
i never tried it.
  Right now in running form the coil resonates at 34.6 (fluctuates) khz,
If i remove windings, or wind another coil to 38.30" the length of wire
will be 6396' and the 1\4 wave with smooth topload will be 6397'-at-
38.5khz, if it would be helpful i would be willing to try another
secondary or remove windings after the geek-A-thon?

Trying how i can with what i have,
Marc


Tesla list wrote:
> 
> Original poster: "Paul Nicholson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>
> 
> Hi Harvey,
> 
> > pray tell me what this deviance from
> > quarterwavelength actually consists of? Is it 10%
> > lower? Is it 15% by added top polar capacity? Is it no
> > known figure of percentage basis compared to that
> > quarterwavelength value,
> 
> The 1/4 wave resonant frequency of a wire, when wound into a
> solenoid, is typically more than 50% higher than that of the
> straight line value.
> 
> The extraordinary persistance of the wire-length myth comes
> from the willingness of people to accept things on faith without
> making even the most basic of cross checks.
> 
> Take a typical TC secondary and measure its unloaded Fres.
> Compute the free space 1/4 wave length and compare it to the
> wire length.
> 
> For example, Terrys 30" coil, in metric units:
> 
>  Diameter: 0.261 metres
>     Turns: 1000
> 
> therefore wire length = 0.261 * PI * 1000 = 820 metres.  Now this
> is a quarter-wave in free space at 300x10^6/(820 * 4) = 91.5 kHz.
> 
> When you measure this coil, the actual Fres is 148 kHz.  If you'd
> tuned your primary to match an expected 91.5khz, it simply wouldn't
> work.  This sort of difference is typical, and the difference gets
> greater as the H:D ratio is reduced.
> 
> There, that was a simple check that could have been done by anyone
> in the last 10 decades.  You can't afford to rely on faith in this
> business.  Criticism, checks, cross-checks, and more checks.
> Absolutely essential.  Makes it darn hard to make reliable progress
> if you're working alone.  Thank goodness for this list.  This is the
> first time in the history of Tesla coiling, as far as I know, that
> so many people (800+ now I believe) have come together in a rational
> forum to compare notes and ideas.  We are very privileged to live in
> this era of Pentiums and pupmans.  Lets try to do justice to that
> position.
> 
> See the comments and graph in
>  http://www.abelian.demon.co.uk/tssp/misc.html
> 
> > I submit that this is mere jumping on a bandwagon of derision
> 
> No, science doesn't work like that. The bottom line is: Nature Rules.
> --
> Paul Nicholson
> --