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Re: Museum Coil Revisited
> Date: Sat, 4 Jan 1997 21:45:52 -0700
> From: Tesla List <tesla-at-poodle.pupman-dot-com>
> To: rwstephens-at-headwaters-dot-com
> Subject: old/ThuJan223:24:00MST1997
> Subscriber: ccurran-at-execpc-dot-com Thu Jan 2 23:12:08 1997
> Date: Thu, 02 Jan 1997 21:06:35 -0600
> From: Chuck Curran <ccurran-at-execpc-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Museum Coil Revisited
>
> Tesla List wrote:
> >
> >
> > Tesla List wrote:
> > >
> > > > Subject: Re: Museum Coil Revisited
> > >
> > > Subscriber: rwstephens-at-headwaters-dot-com Tue Dec 31 09:26:10 1996
> > > Date: Tue, 31 Dec 1996 03:57:13 -0500
> > > From: "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
> > > To: tesla-at-pupman-dot-com
> > > Subject: Re: Museum Coil Revisited
> > >
> SNIP
> > > I do wish to buzz MTC higher than 7 kVA soon however
> > > and try to go for 4X the 50 inch resonator length in output spark
> > > length instead of the only 3X it presently does. I really think it
> > > can! I'd better try it soon though, Chuck Curran is up to something nearly
> > > identical in secondary resonator size, but sporting considerably more inductance
> > > and also thicker wire, and a significantly larger topload C. I don't want to loose
> > > my place. : ) Chuck, I haven't heard from you! : ) I spill my
> > > construction secrets to you trying to help, and you hide. Any hardware store
> > > merchants on this list in Chuck's area, be on the lookout for sales of heavy guage
> > > 200 foot extension cords! : ) Look out Gerry LaBine!
> >
>
> Robert:
> I didn't think I really had anything too out of the ordinary--100% of
> my new coil specs have been already listed! Yup, I hide--in the
> basement working on the primary of late. Just ask my wife. She did get
> me out on New Years eve though!
> >
> >From here on, with any further increases in power I'm going to have to
> > carefully watch the temperature of my stationary tungsten carbide
> pads on the
> > rotary which are merely brazed onto their steel supports. I don't
> want to melt
> > the brazing. These contacts are operated in high speed air blast
> > from a vacuum cleaner blower with two small directed nozzles for
> > cooling. So far this has worked faultlessly with the tungsten, but
> amazingly
> > DID NOT previously when the contact material was mild steel and all
> > other parameters including power level were identical! My contacts
> would go
> > into thermal runaway, incandesce, and vaporize in a steady shower of
> sparks in
> > the blast air stream. MTC's rotary break is run just like D.C. Cox's
> unit, without > any series quench gaps.
> >
> > I posted my ideas on this a while ago, postulating that
> > the tungsten could operate at a much higher surface temperature from
> the
> > getgo without emitting a cloud of vapourized metal ions from its
> > surface, thus preventing the thermal runaway effect. I believe a
> > very micro-thin pool of molten surface metal instantaneously develops
> > at the end of the switch arc with the steel contacts, and not so with
> > the flying thoriated tungsten/stationary tungsten-carbide interface I
> now use.
> >
> This situation does puzzle me right now. I have had limited use of my
> rotary at high power, but it sure has held up with no priblem in August
> and September I was running regularly at over 6000 watts with no
> noticeable electrode wear. The rotary has 12 electrodes--each one is a
> 3/8-16 stud with 3/8" stainless acorn nuts on either end. The two
> stationary contacts are 1" diameter brass by 1 1/4" long with a taper on
> the contact end leaving a 3/8 contact surface. These are adjusted in
> and out on 3/8" threaded rod about 4" long. Lots of mass and it runs
> pretty cool so far. I effectively have 24 rotating electrodes for heat
> absorbtion and the two big brass stationary electrodes that show some
> erosion but only a few thousands deep. I don't know, the new Simpson
> analog meters showed a minimum of 20 amps(sometimes 34) at 300 VAC
> coming out of the autotransformer Robert and the durn thing held up O.K.
> with no cooling fans of any sort. I'm wondering, are your carbide fixed
> contacts/electrodes mounted on smaller diameter rod, less mass to absorb
> heat?? Or maybe mine will just go into a delayed melt-down the first
> time I fire it up this spring! I better get back into the basement
> now--gotta sand the primary form yet tonight prior to mounting the
> primary acrylic supports. Screwed them up the first time,just too long,
> but now they are ready to mount too and then winding the 5/8/" tube.
> Text book coil design, nothing special :-)
>
> Take Care,
>
> Chuck Curran
Chuck,
Sounds like you are doing very well with your rotary gap. I have
experimental results in regards to toploads which shud interest you
on another post tonite.
Good luck on what you yourself proclaim as a 'nothing special' coil. I believe
it will still take synergistic skill/luck/ to make it outperform.
You need to be able to tap into the force Luke! : )
regards,
rwstephens