Re: R: 813 in my vttc...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Brett Miller <brmtesla2@xxxxxxxxx>


--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "Vladimiro Mazzilli"
> <V.Mazzilli@xxxxxxx>
>
> Hi Brett,
>
> With which power supply are you running? Mot?
> Doubled? With shunt or not?
> In my experience I prefer to polarize G2 and bypass
> it with a capacitor.
> Especially in little power tube, to avoid
> destructive flashover.

Hello Vladi,

I am running a very large sized MOT with no shunts.  I
am also running with a doubler.  I have a RL network
(plate choke) on the plate.
No destructive flashovers have occured yet...

-Brett

>
>
>
> Vladimiro Mazzilli
> Ricerca & Sviluppo
> Aros Srl
> Via Somalia 20
> 20032 Cormano (MI)
> Tel. +39 02 66327266 - Fax. +39 02 66327528
> email: V.Mazzilli@xxxxxxx
>
> Web: http://www.aros.it
>
>
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> -----Messaggio originale-----
>
> Da: Tesla list [mailto:tesla@xxxxxxxxxx]
> Inviato: lunedì 12 febbraio 2007 5.08
> A: tesla@xxxxxxxxxx
> Oggetto: 813 in my vttc...
>
> Original poster: Brett Miller <brmtesla2@xxxxxxxxx>
>
> All,
>
> I have gotten satisfactory sparks from placing a
> single 813 in place of the 833A in my vttc system.
> They are not as long as the 833A sparks, but they
> look
> good and the system draws much less power from the
> wall in this configuration.  Plus, the graphite
> plate
> runs pitch black until about 130v is reached on the
> variac.  At full voltage (140v) it gets a cool dark
> cherry on the plate, and the amp clamp shows no
> higher
> than 14a.  This is significant when you consider
> that
> in the same system with the 833A plugged in, the
> meter
> hit 21a peaks at the 140v setting, while making
> sparks
> which were only about 5-6" longer on the avearage.
> I
> haven't even tried optimizing grid leak resistance
> yet, not to mention winding a new feedback coil.
>
> The tube is running as a triode with G1 and G2 in
> parallel, and G3 connected to ground through a
> jumper
> to one side of the filament (cathode) connection on
> the socket.
>
> Here is the video...which is even pretty impressive
> in
> daylight:
>
> http://www.hot-streamer.com/brett/vttc/14inch813.avi
>
> It's a bit over 8 megs in size...but not compressed
> (at least not beyond what my cannon powershot does
> already).  After the voltage reaches 130v or so the
> sparks average about a foot each easily, with sword
> streamers exceeding this by a few inches now and
> then,
> however, they diminish when the Yish caps heat up.
>
> This test has shown me that even though the plate is
> running cool, the tank cap (2 yish 1.1nf in
> parallel)
> gets quite warm to the touch after even a 45 - 60
> second run.  This is a major loss point for my vttc
> since I have found that the longest sparks occur
> during the first 20 seconds or so on the first run
> after the Yish caps are cooled off.  Then
> performance
> drops off by 2 or 3 inches subtracted from the spark
> output.
>
> The Yish doorknobs are inexpensive, great for filter
> (and grid leak) caps, and they will work fine if you
> are just hungry to get started on your 1st vttc.
> But
> they are no substitute for higher quality caps that
> will stay cool.  Luckily, I have a big mica on the
> way.
>
> Working with the 813 is a lot of fun.  It would not
> have gone so well if it weren't for the personal
> help
> I received from John Freau on this 813 project.
> Thanks John!  Also, the project would not have been
> possible if it weren't for Dan Williams, who gave me
> two new 813's.  Thank you Dan.
>
> Cheers,
> Brett
>
>
>
>
>
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