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Re: MicroWave oven Transformer
> Subscriber: unknown-at-apc-dot-net Sat Jan 11 10:43:55 1997
> Date: Fri, 10 Jan 1997 01:50:04 -0800
> From: Open Minded <unknown-at-apc-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Re: MicroWave oven Transformer
>
> Tesla List wrote:
> >
> > > Subject: MicroWave oven Transformer
> > > Subject: MicroWave oven Transformer
> >
> > Subscriber: rwstephens-at-headwaters-dot-com Thu Jan 9 22:21:54 1997
> > Date: Thu, 9 Jan 1997 15:18:22 -0500
> > From: "Robert W. Stephens" <rwstephens-at-headwaters-dot-com>
> > To: tesla-at-pupman-dot-com
> > Subject: Re: MicroWave oven Transformer
> >
> > > Date: Sun, 5 Jan 1997 21:25:09 -0700
> > > From: Tesla List <tesla-at-poodle.pupman-dot-com>
> > > To: Tesla-list-subscribers-at-poodle.pupman-dot-com
> > > Subject: MicroWave oven Transformer
> > > Reply-to: tesla-at-pupman-dot-com
> >
> > > Subscriber: pylon-at-nwlink-dot-com Sun Jan 5 20:46:33 1997
> > > Date: Sat, 4 Jan 1997 19:45:16 -0800 (PST)
> > > From: James <pylon-at-nwlink-dot-com>
> > > To: tesla-at-pupman-dot-com
> > > Subject: MicroWave oven Transformer
>
> <<SNIP>>
>
> > James,
> >
> > The transformer you have just salvaged probably outputs about 2000
> > VAC with 120 volts input. With a variac on the input it would be a
> > marvelous transformer to power a vacuum tube Tesla coil employing an
> > 833-A,single or pair of 810 triodes or a pair or three of smaller 805's etc. More
> > easily available 811-A's could also be paralelled, perhaps four
> > units but you would be stressing their voltage rating (this is known
> > as pushing the outside of the envelope!) : )
> >
> > The filament winding of your transformer is too low to be suitable
> > for any of the popular above mentioned tubes which you may try to
> > employ. You will need a separate filament transformer. I don't have
> > my toob manual handy but I know the 833-A, 810's and 805's require 10 V.
> > The 811-A may be 6.3 volts. If you require this info just ask and
> > I'll be happy to look it up.
> >
> > You can run the tube directly off the transformer through the Tesla
> > primary tank circuit without rectifier diodes or filter cap. This
> > arrangement actually gives you longer streamers by pulsing the tube
> > oscillator at 60 times a second with half the time (when the 60 Hz
> > sinewave is negative) cutting off conduction and allowing the tube to
> > rest just over half the time.
> >
> > The neat result is that when it does conduct, for a given AVERAGE
> > power level which equates closely to the tubes actual specified power rating,
> > you can hammer the tube at nearly twice its rated power level safely. : )
> > This trick gives you an effective peak power of more than twice the average
> > power level of the tube, while costing less in circuitry and components.
> >
> > Brent Turner has a nice twinned 805 vacuum tube TC on his home page
> > which looks like it is powered by just such a transformer. This is
> > also a configuration well explored by an experienced newcomer most
> > welcomed to this list, John Freau.
> >
> > rwstephens
>
>
> You are correct. The transformer was given to me, and came from an
> old industrial microwave oven. The transformer originally cranked out
> about 2200 volts at about 200 mA or so. I was able to re-wire it to
> put out 1100 volts at 400-500 mA. (has split secondaries) Got my hands
> on another transformer rated at 2400 volts at 500 mA...just itching to
> power a set of 810's or 8000's...!
>
> - Brent
>
> (bturner-at-apc-dot-net - the other reply address is for anti-spamming.)
Brent,
You sure do nice work. That little tube TC is beautiful. The bigger
transformer you just mentioned will probably power three 810's in
parallel in half wave, raw AC on the plates mode. You should be able
to get 18 inch brush/streamers at that power level. That's what my 3
X 810 unit does at about the same AC plate voltage.
regards,
rwstephens