Re: 1916 Era Quenched Gap

Tesla List wrote:
> Original Poster: "Steve Young" <youngs-at-konnections-dot-com>
> To all spark gap enthusiasts,
> Lindsay Publications sells a very interesting republication entitled "High
> Frequency Apparatus" by Thomas Stanley Curtis which describes 1916 era TCs
> and how to make the various components.  In it is described what he calls a
> quenched gap.  He says "The effects produced with the high-frequency coil
> in connection with a quenched gap are truly remarkable.  Instead of the
> thin, wiry spark ordinarily seen, the discharge takes the form of a flame
> as thick as a man's wrist when conditions are right.  At times the actual
> length of the discharge is reduced, but with everything in resonance an
> increase both of thickness and length will be noted."  He says the sound is
> "a loud crashing hiss".
> Keep in mind that in 1916, the coils he described in the book only had a
> ball an inch or so in diameter as the discharge terminal (no large torroids
> or spheres).  I wonder if the flame-like discharges would still occur with
> higher capacitance toploads - probably not.  The effect he describes sounds
> a lot like VTTC discharges.
> What is the quenched gap he speaks of?  His construction examples are 4
> inch diameter by an inch or so thick machined castings of solid copper.
> "By making the spark gap electrodes very massive, facing them off very
> accurately in a lathe, providing large radiation surface on each electrode,
> and, finally, by supporting the electrodes in such a manner that the
> separation of their faces is but a few thousandths or perhaps hundredths of
> an inch, we have what is commonly termed the quenched gap."  The back sides
> of the disks have machined fins to act as heat sinks to help keep the gap
> cool.
> He says "The large surface and the short gap increase the total number of
> discharges per (primary transformer) alternation of the current from one or
> two per alternation to several hundred or perhaps a thousand".
> Can anyone report the results of modern day experiments with such a
> quenched gap?

	I have an AMRAD "1 kW" quenched gap, circa 1918.  It works just fine
with a coil using a 12 kV, 60 ma transformer.  Because the separating
washers have compressed with age, the gap breakdown voltage is smaller
than I like, but my coil produces fat 18" sparks.  Setup is down now
(table used for vacuum system), but when I put it up again I'll take
some pictures and post here.  Very good gadget if you want "fat"
continuous arcs rather than longer and intermittent streamers.