Re: Gaps

Tesla List wrote:
> >> Subject: Gaps
> Subscriber: mycrump-at-concentric-dot-net Sun Feb  2 17:40:26 1997
> Date: Sun, 2 Feb 1997 09:46:23 -0500 (EST)
> From: "Daryl P. Dacko" <mycrump-at-concentric-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Re: Gaps
> At 10:10 PM 2/1/97 -0700, you wrote:
> >> Subject: Gaps
> <snip>
> >Mr. Curtis describes what he calls a Quenched Gap beginning on page 41. It
> >consists of two LARGE, Heavy, Thick, pieces of metal that are cylindrical
> >in shape, with the facing ends ground and polished flat. The machined ends
> >are then placed from 1/1000 to 1/100 of an inch apart. Due to the massive
> >way it is built it can sink a fair amount of heat. This keeps the
> >electrodes cool and allows for hundreds to thousands of individual
> >discharges per AC cycle. This does not affect the resonant frequency, but
> >does affect the nature of the discharge from the secondary. Mr. Curtis is
> >lavish in his praise of this spark gap over all other types. He says it
> >produces a series of "very short, clean, and nearly undamped surges". He
> >mentions that as it heats up it deteriorates in performance. Today we would
> >probably force air cool the device. It appears from the description that
> >there is no need to force air THROUGH the gaps. (They are very close
> >together!)
> >
> >By the way, these things were quite heavy and massive, with face diameters
> >of three inches and more, and thicknesses of about an inch and a half
> >(minimum), and greater. The sheer mass causes the heat to be removed
> >rapidly. The large parallel surface area allows for MANY conduction paths,
> >and thus high RF currents.
> >
> >I do not have the facilities here to machine such a beast, but there may be
> >some of you out there who have access to such machinery as large lathes,
> >etc.  Does anyone know if any Coiler has built such a quenched gap and
> >reported on its performance?
> I have a set of gaps from an old dithearmy (sp?) machine, that seem to operate
> much as you describe.
> There are four 3/4" Dia copper rods with massive copper cooling fins attached
> to each rod. The rods are individualy adjustable to no more than 1/32" or so
> per gap. Two sets of these gaps were used for a total of eight gaps.
> A 12" fan blew air across the fins and gap system to cool them down, total
> system power was 2.5 Kw
> Only 5KV was applied to the system, so the gaps were VERY tight to get proper
> operation. You could look into the gaps and see a mass of sparks between the
> gaps, not just one at a time.
> I rewound a new secondary and primary at attached it to the system and with
> a 1" ball electrode got about 12" to 18" spark...
> It looked a LOT like a tube coil, more corona like, with many fans of arcs
> radiating out...
> I'd say the gaps worked great, but quite a bit diffrent arcs than with a air
> blast gap. Likely I was gettting "undamped surges" and more of a CW output
> than your basic rotary or static gap.
> I'm hopeing to run more experiments with these gaps this spring, once the
> snow melts.
> Daryl

Daryl -

  What you are observing is a high degree of quenching in the gap. The
gaps are firing and extinguishing many more times per second than the
60Hz line frequency. A quenched system generates more power off the
coil, but typically shorter spark length than a 'conventional' gap.

- Brent (bturner-at-apc-dot-net)