Re: [TCML] 35 KVA Vacuum Tube Tesla Coil

[Roger Smith <rwsmith@xxxxxxxxxxxxxx>]

On 7/4/2011 12:56 PM, Carlos Van Camp wrote:
> Hi Roger,
> Nice job!
> I have been using the next valve size up (a 4CX15000a), and it is 
> capable of 50kw input.
> So far I have only put about 35kw into it so we are on a par there...
> I am only getting 40" of arcs at best (6 individual brushes of 40" 
> each coming of the top electrode), so you are doing well.
> Unfortunately I designed the Primary/secondary in the hope of much 
> bigger arcs (very long secondary coil) so I think this is my downfall 
> in efficiency...
> I am planning to rebuild the primary/ secondary arrangement, but first 
> I am running a serries of controlled benchtop sized experiments to see 
> if I can improve the overall circuit efficiency.
> I am trying to get my head around what makes the arcs get fatter with 
> CW operation, as oppose to getting longer as with pulsed operation.
> The search for the holy grail continues...!
>
> What circuit did you use?
>
> Kind regards,
>
> Carlos
> ----- Original Message ----- From: "Roger Smith" <rwsmith@xxxxxxxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Monday, July 04, 2011 9:45 PM
> Subject: [TCML] 35 KVA Vacuum Tube Tesla Coil
>
>
> >     I got a hold of a big ceramic triode (3cx10000a3) a few years ago 
> > and I finally built a tube coil with it.  It is powered by a 5 KVA 
> > pole transformer at up to 35 KVA and I am now getting 50"  fat bushy 
> > sparks. Here is a link to the video on it 
> > http://www.youtube.com/watch?v=B8536fYHvGM&feature=feedlik 
> > <http://www.youtube.com/watch?v=B8536fYHvGM&feature=feedlik>      I 
> > haven't seen any other  VTTCs like it so It's hard for me jug the 
> > efficiency of it.   Any suggestions are welcome.
> >
> >     Roger
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>
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Hi Carlos,   The circuit I used is basically the same as the circuit 
Steve Ward has on his web site for his 833 VTTC.    I don't claim  to be 
an expert on this stuff but my gut feeling is that since these VTTCs are 
so tightly coupled they tend to act a little more like transformers than 
Tesla coils so if you have too few turns in the primary,  that might be 
a problem.  The objective here isn't to get the highest voltage 
theoretically possible but rather to get the voltage and the current in 
the right proportions to match the load of the spark.

      It seems like a loosely coupled VTTC would be self matching but I 
haven't had much luck with that approach.     Having said all this ,  I 
think I have a long way to go to get my coil as efficient as it could 
be.   The 50" inch sparks are nice but 35 KVA is a hell of a lot of power.

   Good luck with your endeavors,  Roger
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