Re: Help with difficulty finding overtones or nodes?

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

Original poster: "Paul Nicholson" <paul-at-abelian.demon.co.uk> 

Phil LaBudde wrote:

 > Thing sure acts lumped, not distributed

Well,  it will if you don't pick up any overtones :)

 > 4" x 28" secondary of 1000 turns #22.

The fundamental should be around 465 kHz without a topload,
with the first overtone (3/4 wave) at about 1150 kHz, the
next (5/4 wave) around 1680 kHz, and so on.

Set your generator to do square waves and try to excite
the coil with harmonics.  You would need to look for
coil responses through the scope probe, not the oscillator
voltage.

 > ...according to the Corum paper

The Corums tried to suggest (erroneously) that 'lumped' or
'transmission line' where two different modes of operation,
over which the coiler had some choice, whereas in fact they
are simply alternative *models* by which the coil may be
analysed.  This appeared to fuel a silly debate which still
flares up everytime someone comes across that dreadful 'Class
Notes' paper :)

For comments on this, see
  http://www.pupman-dot-com/listarchives/2000/August/msg01119.html

For some brief notes on how the overtones are affected by
toploading, see
  http://www.pupman-dot-com/listarchives/2004/July/msg00409.html

In recent years lots of study has been done on coil resonances.
If you can give details of your toploads, we can calculate where
the overtones will be found.
--
Paul Nicholson
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