Jim wrote>>" The wire test is also pretty instructive in general"
Defiantly!
Just the presence of your own body (doing the test) in the area close to a
bigger coil can cause a difference. Doing it on larger secondary's is best
done with a long lead to avoid this. Low ceilings will affect things as well
- hence JavaTC asking questions at the beginning, about the environment of
the coil.
Jim wrote>> "some egregious error like having the topload not connected to
the secondary"
Or scoping the primary without shorting the spark gap out? (cough)
Phil
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Jim Lux
Sent: 04 April 2014 17:06
To: Tesla Coil Mailing List
Subject: Re: [TCML] Secondary Resonant Frequency test ??
On 4/4/14 8:42 AM, Phil Tuck wrote:
> Teslalabor wrote: "it is completely useless"
>
> No no, I wouldn't that!
> True the streamers have a capacitance of a couple of pf / foot to
> upset things, but the scope method gives a very good estimate and the
> smaller the coil the more accurate it should be - less output, less
effect.
> You simply use the 'wire' method mentioned and then compare the
> difference with and without the wire. I tune the primary around 8%
> lower, (82 down to
> 74 KHz approx)
> Only trouble with the scope method is that you get harmonics show up
> as well, so doing a sweep involves looking for the highest amongst the
> several peaks that will occur. Using JavaTC beforehand will tell you
> the figure reasonably accurately as a guide though, to avoid mistaking
> a harmonic as the correct peak.
> Phil
>
And to echo Phil, the other thing you can check for is some egregious error
like having the topload not connected to the secondary. Oddly it sort of
works, because the "sparkgap" at the top of the secondary connects it to the
topload, sort of.
(not that I'd ever have done that, no, never, uh-uh)
measuring your secondary is also handy for other reasons: how many of us
have tried increasing Csec by piling something else on top of the toroid
(like another toroid, or a bucket, or a pumpkin, or an aluminum christmas
tree).
The wire test is also pretty instructive in general. You can see if moving
stuff around your test area causes a "significant" change in resonant
frequency.
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