Hi and Thanks Calvin,
I am familiar with one of these fellas and it has been some time since
looking at his site. I will be taking a good look and checking the others
also :^)
Chris Reeland
Ladd Illinois USA
Sent from my Lenovo Tablet
On Sun, Jan 15, 2023, 7:01 PM Calvin Holmes <me@xxxxxxxxxxxxxxxx> wrote:
> Hi Chris,
>
> I’ve stayed within a very similar frequency range.
>
> Teslista555 is the best source I’ve found regarding a variety of
> frequencies in VTTCs.
> https://www.vn-experimenty.eu/teslov-transformator/vttc.html?filter_tag[0]=11
> <
> https://www.vn-experimenty.eu/teslov-transformator/vttc.html?filter_tag%5B0%5D=11
> >
> The GU-5B pages in particular:
> https://www.vn-experimenty.eu/teslov-transformator/vttc/vttc-11.html <
> https://www.vn-experimenty.eu/teslov-transformator/vttc/vttc-11.html>
> https://www.vn-experimenty.eu/teslov-transformator/vttc/vttc-12.html <
> https://www.vn-experimenty.eu/teslov-transformator/vttc/vttc-12.html>
>
> JMartis also has a higher frequency VTTC video with a GU-39B:
> https://www.youtube.com/watch?v=CH_0H_-UZIc <
> https://www.youtube.com/watch?v=CH_0H_-UZIc>
> Magic Tee has a smaller low MHz VTTC:
> https://www.youtube.com/watch?v=BRj2RGca36w <
> https://www.youtube.com/watch?v=BRj2RGca36w>
> https://www.youtube.com/watch?v=UEmmOXIQwZw <
> https://www.youtube.com/watch?v=UEmmOXIQwZw>
>
> Best,
> Calvin
>
> > On Jan 15, 2023, at 15:16, Chris Reeland <chrisreeland@xxxxxxxxx> wrote:
> >
> > Hi Fabio,
> >
> > Those ceramic transmitting capacitors you linked are exactly the type I
> was
> > thinking of and I find it interesting that you have had good luck on some
> > MMC polypropylene caps so far.
> >
> > Just wondering, since you are in Italy (I think I have this correct),
> what
> > kind of mica cap availability do you have over there in that part of the
> > world and made from what countries out of curiosity? For me/we in the
> USA,
> > we have a large selection of good older USA made mica transmitting
> > capacitors especially from the 1940's to late 1960's pretty easily
> obtained
> > that are constructed with the "finest India ruby mica" dielectric. They
> had
> > especially good quality control in my opinion of this era of
> manufacturing
> > mica capacitors. And good sources of raw ruby mica, other types of mica
> is
> > not as good, and from what I know, these days, good raw ruby mica is much
> > harder to come by for manufacturers, so newer ones can be made of other
> > types of mica. There is only "so much out there" of this mica type in the
> > mines. For me, I have had only one mica cap destroyed because it was way
> > too small for the current handling requirement in how the VTTC was set
> up,
> > met voltage, but... learned the hard way...
> > For me, when sized correctly for both voltage and current handling
> > capability I have had great performance and I really push my tube coils
> > hard at times and for really long durations too. And also, another note
> > here, is these older ones have a metal brass nameplate which shows
> > typically three different frequency numbers and the associated amps at
> that
> > frequency. The amp handling goes down the lower the frequency. And when
> > hitting a point in much higher frequency, it will again go down in amps
> in
> > the rating.
> > Just like those good Soviet ceramics, they get much larger and heavier
> the
> > good ones.
> >
> > Another curiosity is, what are the frequencies of your VTTC'S.
> > For me, the lowest running frequency I have experimented with so far,
> about
> > 200khz and I have been all over in-between up to 700khz. I have yet, to
> > experiment going into the MHz range... some day...
> >
> > Chris Reeland
> > Ladd Illinois USA
> >
> > Sent from my Lenovo Tablet
> >
> > On Sun, Jan 15, 2023, 9:54 AM Fabio Bragonzi.it <mcggyver@xxxxxxxxxx>
> wrote:
> >
> >>
> >> Hi Jordan and all!
> >>
> >> I personally had some excellent results either with MMC capacitors
> >> (using MKP or KP type caps) or big ceramic capacitors (flat disk or
> >> hollow tube type) but i struggled to get proper results with doorknob
> >> capacitors (molded in plastic) or mica capacitors (molded inside a
> >> bakelite or ceramic case).
> >>
> >> For a better explanation, the doorknob i tried wasn't working as
> >> expected (quick overheating, resulting in a shift of resonant frequency)
> >> and all of the mica capacitors i tried worked just fine for a short
> >> period of time.... until they fail.
> >>
> >> I strongly suggest an old Soviet ceramic capacitor because are very
> >> strong and also quite cheap (something like these):
> >>
> >> https://www.ebay.it/itm/193245707970
> >>
> >> https://www.ebay.it/itm/284028401115
> >>
> >> https://www.ebay.it/itm/275420278203
> >>
> >> Please note that these capacitors almost always have the maximum
> >> reactive power rating printed on the case, but most sellers never give
> >> you this information
> >> (FYI, the cyrillic writings "kBAp" means "KVAr")
> >> The rated voltage of the grid leak capacitor shall be equal or greater
> >> than the max voltage ratings of the plate;
> >> almost any kind of capacitor (except electrolytic) is adequate for the
> >> purpose.
> >>
> >> Ciao!
> >> Fabio.
> >>
> >> Il 10/01/2023 18:11, jordan simmons ha scritto:
> >>> Hey All,
> >>> I have been looking for a while to find some suitable doorknob caps
> for a
> >>> GU 81M VTTC. Running ~350kHz probably around 1kW, 1.5kW if I really
> push
> >>> it. C-tank between 1.8-2.5nF.
> >>> Is it worth it to get doorknob caps? Or is it more wise to roll with an
> >> MMC
> >>> tank?
> >>> And what about the max voltage ratings on the grid leak capacitor? Is
> it
> >>> critical for it to be plate supply rated, or derated to the tube's
> >>> datasheet?
> >> _______________________________________________
> >> Tesla mailing list -- tcml@xxxxxxxxxxxxxxx
> >> To unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx
> >>
> > _______________________________________________
> > Tesla mailing list -- tcml@xxxxxxxxxxxxxxx
> > To unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx
>
> _______________________________________________
> Tesla mailing list -- tcml@xxxxxxxxxxxxxxx
> To unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx
>
_______________________________________________
Tesla mailing list -- tcml@xxxxxxxxxxxxxxx
To unsubscribe send an email to tcml-leave@xxxxxxxxxxxxxxx