RE: mysterious coil failure (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 29 Oct 2007 13:04:46 +0000
From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: 'Tesla list' <tesla@xxxxxxxxxx>
Subject: RE: mysterious coil failure (fwd)

One doesn't need a signal generator or scope of any kind to measure
coupling.  You need only know the primary and secondary inductance, and
perform the measurement described at
http://www.classictesla.com/download/M_and_k_Measurement.gif

I've not found it necessary to include the RC network across the
secondary.  The wording is confusing with "Take concentric readings from
meters."  I think what was meant is to take both primary current and
secondary voltage measurements at the same time on separate meters.

Regards, Gary Lau
MA, USA

> From: resonance <resonance@xxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: mysterious coil failure (fwd)
>
>
>
> You need to check your coeff. of coupling and usually keep it below 0.12 for
> most classic spark gap coils.  Some of my coils run best with greatest spark
> output at .08 to 0.1 range.  A local Univ. or tech college with a storage
> scope and sig gen can help you do this.  The equations and procedures are in
> the Tesla List Archives.
>
> If your coeff. of coupling is producing a "double hump" then your coupling
> is too tight, energy is being wasted, and your coil will hit HV peaks at two
> points --- sometimes not at the end of the sec.
>
> This produces tracking and eventually destruction of the coil.
>
> Also, be sure to always sand both interior and exterior of any coilform
> prior to winding.  Also use some small acrylic baffles approx 6-8 inches
> down from each end in the sec.  Silicone into place with GE Silicone II  ---
> available at most hardware stores.
>
> Dolph's AC-43 has much greater anti-tracking properties than polyurethane,
> and it's price is reasonable if you consider the amount of repair time that
> is required when a coil fails.
>
> Dr. Resonance
>
> Resonance Research Corp.
> www.resonanceresearch.com
>
>
> ----- Original Message -----
> From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Sunday, October 28, 2007 8:03 PM
> Subject: RE: mysterious coil failure (fwd)
>
>
>
> ---------- Forwarded message ----------
> Date: Sun, 28 Oct 2007 19:50:56 -0400
> From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: RE: mysterious coil failure (fwd)
>
>
> Thanks guys,
>      I don't think it was a shorted turn, there is no carbon on the inside
> but there is a tiny black spot on the outside (I don't use end caps on my
> coils, is this bad?).  I attach my RF ground by a copper strap, soldered
> onto the end of the bottom turn, I think it arced from the sharp edge of
> the strap to the wire above it (turn 2).  This occurred underneath of the
> several layers of electrical tape coated with polyurethane insulation on
> the bottom.  One other detail I forgot to mention, I set the coupling as
> high as I could get it that night to make up for decreased performance
> from wind and humidity, so that may have contributed.  I'll sand her down
> and rewind the bottom and see if it works again, thanks guys.
>
> Scott Bogard.
>
> > Date: Sun, 28 Oct 2007 11:07:40 -0700
> > From: tesla@xxxxxxxxxx
> > To: tesla@xxxxxxxxxx
> > Subject: Re: mysterious coil failure (fwd)
> >
> >
> > ---------- Forwarded message ----------
> > Date: Sun, 28 Oct 2007 11:01:32 -0800
> > From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
> > To: Tesla list <tesla@xxxxxxxxxx>
> > Subject: Re: mysterious coil failure (fwd)
> >
> > Hi Scott,
> >
> > Yes, the glowing spot is either a shorted turn or carbon track. It may
> > be a shorted turn and easy to fix if right on the bottom, and "if" it is
> > like the very bottom turn, it's probably too much power for too long a
> > period. I've had this happen on my 4" coil even with low coupling. If
> > enough power is provided, it can cause extensive heating a greatest
> > heating on the bottom of the secondary (highest current). If you were to
> > continue running it, a nice little fire will begin. If it's a shorted
> > turn, you'll have a nice black carbon ring around the entire turn. Real
> > easy to fix obviously.
> >
> > Take care,
> > Bart
> >
> > Tesla list wrote:
> > > ---------- Forwarded message ----------
> > > Date: Sat, 27 Oct 2007 22:10:06 -0400
> > > From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> > > To: tesla@xxxxxxxxxx
> > > Subject: mysterious coil failure
> > >
> > >
> > > Hey guys,
> > >      I was running my 6-in MOT coil tonight for my little cousins, and
> > > it
> > > died and I cannot figure out what is wrong.  The spark gap fires fine, I
> > > did not adjust anything, it just died between runs, and won't arc except
> > > to a grounded rod (it acts like it is badly out of tune, but like I
> > > said,
> > > I adjusted nothing).  The only thing different I notice, is that there
> > > was
> > > very high humidity, and I could see a tiny spark at the base of the
> > > secondary.  It isn't arcing to anything, it is just a glowing spot, that
> > > melted through the electrical tape insulation.  I'm stumped, I guess
> > > I'll
> > > tear the insulation off of the bottom of the sec' coil and see if
> > > anything
> > > is amiss, but I've never had a failure like this before.  The only other
> > > possibility is that somehow my ballast malfunctioned, but I don't think
> > > so.
> > >
> > > Scott Bogard.
> > >
> > >
> _________________________________________________________________
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> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
>
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