Re: Spark gap resistance

Hi Reinhard,

> Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net> 
> Hi Bert, all,
> > Original Poster: Bert Hickman <bert.hickman-at-aquila-dot-com>
> > Barry and all,
> > The "big Fleming book" is most likely "The Principles of Electric Wave
> > Telegraphy and Telephony" by John Ambrose Fleming, Longmans, Green and
> > Co.
> Snip
> > Zenneck found that the "equivalent" gap resistance, when the gap was
> > predominant source of energy loss, was inversely proportional to the
> > current (more current means lower Rg), directly proportional to the
> > squareroot of the inductance (more inductance means higher Rg), and
> > inversely proportional to the squareroot of the tank capacitance (more
> > capacitance means less Rg).
> I think you just found the true explanation why my low voltage driven
> coil is a good performer. I just "happen" to fullfill everything Zenneck
> finds to be "good" for low gap resistance. My primary current is ~
> 600A (will be 1.5kA in the full version), my cap is relatively big (67nF
> for 7500V) and my primary inductance is pretty low at 23.44|H. So,
> even though I am using a crude and cruddy 10 piece flat static gap
> (with a seemingly high equivalent resistance) and a low voltage power
> source, it is "compensated for" by the way I constructed the TC tank
> circuit (i.e: high current and capacitance and low inductance).

I have a large C/low L primary coil in one of my machines and it 
works very well too. However, it doesn't approach the efficiency of 
other coils and it can be mathematically demonstrated that low gap 
resistance does not mean more efficiency. Indeed, a lower gap current 
means a lower percentage of total power lost in the gap.