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Re: Still mystified by odd TC behavior, what gives?

Original poster: "albert hassick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <uncadoc-at-juno-dot-com>

Hi Jonathan.  I too have had Tesla coils give outstanding spark gap
output with little or no secondary output. All I know is that if the
capacitance that you have is not properly tuned to the primary coil then
you will get lots of spark gap action, but no output at the secondary. 
Sounds as if your coil will not quite accept the capacitor that you have
now.  Maybe you could supplement it with a few beer bottle caps just to
see if you can get some output at the secondary.  Your existing cap must
be functioning because if it had fried then you would not get any arc at
all from the spark gap.  Yes, your big cap could be borderline and
possibly causing your problems, but I feel that your tank is lacking just
a wee bit in total capacitance in relationship to all the other
components of your coil.  It is also possible that this cap may be
working ok but is just too large for your coil parameters.  Again, try to
series or parallel some bottle caps just to see if you can get this coil
to spark.   This will at least give you a starting point for improvement.

On Sat, 19 May 2001 10:26:46 -0600 "Tesla list" <tesla-at-pupman-dot-com>
> Original poster: "Jonathan Peakall by way of Terry Fritz 
> <twftesla-at-qwest-dot-net>" <jpeakall-at-mcn-dot-org>
> Howdy All,
> I have been struggling for over a week to figure out what the heck 
> is
> going on here. If anyone can help me, I'd be soooo happy. Here is 
> the
> situation:
> Basic coil specs:
> Small secondary, 450 wraps of 22 AWG on a 3.5" form.
> Primary: Either a 12 turns 12 AWG auto wire on a 6.5" form, or 15 
> wraps
> 10 AWG auto wire on a 8" form.
> PSU: Either a 12kv/120ma or 15kv/60ma.
> Vacuum single gap
> RF filter ALA Terry
> I recently got a Resonant Research Inc. .025 (actually tests to 
> .023)
> tank cap. When I try to use it, with either transformer or even 
> with
> both ganged up in parallel, I get no output from the secondary,
> regardless of how I tune the primary or set the SG. I can draw a 
> wimpy
> spark to a ground rod, but that's it. The gap fires fine over a 
> range of
> settings. As soon as I add another cap in series to the .023 and 
> lower
> the capacitance, it fires up. Yet the gap isn't acting as I have 
> seen in
> the past with too large a tank cap, which has always resulted in 
> erratic
> SG performance.
> The only thing I can think of is that the "sweet spot" is really 
> small,
> and as I only have taps on each turn on the large primary I haven't 
> hit
> it right. Is it possible for the tuning to be so sensitive that one 
> gets
> no output unless really close? The gap sounds mean and hot, but is 
> it
> possible that the .025 cap is damaged? It seems unlikely considering 
> the
> fury of the gap.
> If you can help, you're my Hero!
> TIA,
> Jonathan Peakall (The other OTHER Jonathan)
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