Re: Spark Gap Evaluation

From: 	Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
Reply To: 	bert.hickman-at-aquila-dot-com
Sent: 	Friday, August 01, 1997 2:17 AM
To: 	Tesla List
Subject: 	Re: Spark Gap Evaluation

Tesla List wrote:
> From:   Richard Wayne Wall[SMTP:rwall-at-ix-dot-netcom-dot-com]
> Sent:   Tuesday, July 29, 1997 4:33 PM
> To:     tesla-at-pupman-dot-com; rwall-at-ix-dot-netcom-dot-com
> Subject:        Spark Gap Evaluation
> 7/29/79
> R.Hull, Bert H., Malcolm et al,
> Has anyone captured a firing TC spark gap discharge on a digital scope?
> If so, what is the initital rise time?
> Has any one measured the spectral content of a firing TC spark gap?


I don't have a digital scope. Only a regular and an analog storage
scope. There's a lot of very high frequency "hash" associated with the
primary spark gap, caused by parasitic inductance and capacitance. The
gap itself "fires" very quickly (quicker than the bandwidth capabilities
of my scopes). However, the primary current going to the coil is
actually quite "clean", however, looking mostly like a nice damped
sinusiod. The voltage, however, is much more difficult to measure
beacuse of the extraneous high frequencty hash that's superimposed by
the gap and parasitic elements.

A spectrum analyzer would be very nice to have for measyuring spectral
content. However, my boss won't let me get his $44,000 unit within 3
miles of my running coil! :^( From what I can tell from my scoped
measurements, I'm easily getting parasitic oscillations that go up into
the 10's of MHz. I can't tell what proportion is in what frequency
ranges, but its clear that the overwhelming majority of the energy being
transferred to the coil is concentrated in the fundamentals and
sidelobes of the coil (about 81, 90, and 99 kHz for my coil) depending
upon whether I'm quenching optimally or not... mostly not.

-- Bert H --