Re: Tube coil makes sparks
Tesla List ha scritto:
> Original Poster: David Trimmell <davidt-at-pond-dot-net>
> At 04:18 PM 3/9/1999 , you wrote:
> >Original Poster: Brandywine <brandywine-at-writeme-dot-com>
> >Fellow Coilers,
> > There has been some debate over the usefulness of the MMC capacitor
> >arrangement. I am currently using 6-- 0.018 uF, 1600Vdc, Panasonic
> >metallized polyprop caps in series for the tank capacitor (result =
> >0.003 uF). They were mildly warm after a 5 minute run at 4000 Vac and
> >probably 4+ kW. I was hoping they would run stone cold. A permanent
> >setup could incorporate 24 caps in a series parallel arrangement, for
> >example. Despite the modest heating, I must tentatively conclude that
> >they are satisfactory for high power tube coil duty.
> Glad to here that you have had first light with this coil. I have been
> using the Panasonic caps also, I am using 10 of the 0.015 uFd-at-1.6KV in
> series wired so I can tap the last 4. They do perform well in my opinion,
> but they get warm after several minutes, although, even after the heating,
> they do not loose capacitance value, as do the doorknob variety. I must
> add that they are of great quallity, as mine have all measured within 2% of
> their rated value.
> > I have in my possession a total of 4-- 833As. It turns out that one
> >of these produces a beautiful blue glow consistent with John F's
> >description of a current sucking corpse that is distinctly unusable. Of
> >the 3 tubes remaining, 2 have graphite plates. To say that they are more
> >stout than those with conventional plates is an understatement---where
> >the conventional plates are bright orange, the graphites are barely
> >glowing. I may need to bias the tubes separately.
> Sorry to here about that tube. Yes! Those Graphite variety are real beasts!
> I have just tried my three in parallel (2 graphite 1 sheet metal), and the
> poor sheet metal one gets very bright, while the Graphite ones show no
> color at all on the plates.
> > I'm using a 100 watt, 10K variable Ohmite resistor for grid-bias
> >duty. $ 25.00 from Digikey. I almost bought the 225 watt version. Wish I
> >had. The 100 watters can get quite hot, especially when less than half
> >of their resistance is utilized. In retrospect, it may have been better
> >to obtain several fixed value units so that the full heat dissipation
> >capacity of the single resistor may be mobilized.
> I have to agree, I use several in series (100 and 200 watt) and they still
> get hot.
> David Trimmell
> > So there is my report. Much work to do. The cancerous desire for more
> >power was felt very early on. I know that 3 tubes will produce much more
> >than 20" sparks, but a gentlemen at Elex electronic supplier mentioned
> >the availability of 10,000 watt industrial oscillator tubes. ...
> >Dave Hartwick
> I've satisfactory used mmkp or mkp or kp capacitor in a tube or semiconductor
> ( mosfet) coil in series paralleled configuration. My preferred type is
> Arcotronics R.73 or RIFA types or philips 2222378 or Roederstein 1841.In My
> mosfet coil I use
64 device 3.3nF series paralleled connected to obtain 8X8 3.3nF each type is