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Re: 8-9 RFI noise thoughts.

Hi Alwyn,

	You bring up a very good point.  The UHF gap oscillations are probably
more based on plasma physics rather than electronics.  Although we can
"simulate" these waveforms with Ls and Cs.  That is probably not too
realistic.  However the use of ferrites does seem to significantly affect
the UHF oscillations.

	The length of the primary and interconnect wiring is 23.2 meters.  The 1/2
wave frequency is about 6.45MHz.  This would be in the range of the 5-30MHz
burst.  

	Just like the old 1/4 wave secondary theories, there is a question if the
primary is a lumped L and C or if this frequency is related to wave
propagation along the primary coil.  I really cannot say for sure but I
would think the magnetic coupling in the primary coil would make it more of
a lumped situation.  It may be difficult to probe the right spots (1/4 in
from each end) in the primary coil.  However, the currents at the center
and spark gap should be 180 out of phase.  Perhaps one could tap into and
get information there?  I am not sure at just this moment...  

	Hopefully, in a short time, there will be a bunch of people with fiber
probes to test things like this.  I probably won't have time in the next
few weeks but I will ponder it...

Cheers,

	Terry


At 04:58 PM 8/18/99 +0100, you wrote:
>Hi Terry,
>
>I think your trying to account for the wave effects with lumped parameters.
>
>When the gap fires a wave probagates from each side of  the SP.  they will
>have oppositer polarities. The waves will be partialy reflected at each
>change of
>impeadance.  SP to interconnection, interconnection to coil, coil to
>interconnection etc.
>
>If I remember correctly your primary is about 30m long.  The wave velocity
>will be some were between a half c and c. If its half a wave (I now think)
>then thats a frequency some where between 2.4MHz and 4.8MHZ.  The wave
>should be at a maximum one quater from each end of the primary as the waves
>will cancel at the SP and at the center of the primary.  Check it out.
>
>
>
>Regards Alwyn Jones (FL)
>
>
>
>
>