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Re: Racing Sparks

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Jared,

Oops, I just thought of one more cause:

1. Too much power for the coil size. Topload voltage is too high for the coil height. Probably requires a topload that is too large and breakout doesnt happen soon enough.

2. Too much coupling. The energy coupled into the coil is more concentrated
in the lower turns and less spread out resulting in an energy wave
propagating up the coil that causes too much stress between windings.

3. Out of tune.  This can result in exitation of the higher resonant modes
that can cause a voltage node at an intermediate position up the coil.

4.  Topload is too small allowing for greater exitation of the higher
resonant modes.

5. Bang energy is too large for the coil size. This results in an energy wave that is too large. Sorta related to #1 and the same mechanism as #2

Gerry R..

Original poster: Jared E Dwarshuis <jdwarshui@xxxxxxxxx>

It is possible to get racing sparks without tight coupling. Larry and
I deliberatly made a 1.5 wave coil with a centered primary that had no
top end capacitors. What we found was racing sparks that existed only
at the quarter wave sections at the ends of the coil.(It looked like a
fiery Q-Tip).  When we added secondary capacitance the racing sparks
disapeared.  (Draw your own conclusion!)

I have noticed that tightly coupled coils are fussy about tuning. They
want the primary to be tapped in just the right place, and the spark
gap needs carefull tweaking. Lose coupled coils are more forgiving
about tuning.

Jared Dwarshuis