Re: [TCML] Is this 2,3kW Triode suitable for a VTTC?

[Futuret <futuret@xxxxxxx>]

Hi Stefan,

In the past, I compared my VTTC operation using 4.2kV, from a
doubler, and from a plate transformer.  Both methods gave the
same spark length.  The difference was that in staccato mode,
I got better sword sparks using the doubler.  I don't know why
you're seeing such a big difference.  If anything, the shunts in
an MOT tend to reduce or limit the spark length.  I often remove
the shunts to get more power, however that does make the MOT
less efficient (more core saturation).  

Have you tried doubling the 2kV MOT output to get 4KV?  I usually
use at least 4kV for my VTTCs.  The spark length generally 
increases linearly with the input voltage.  Of course the input
power rises by 4x when the voltage is doubled.  Using a doubler
should almost double the spark length.  

I usually use around 5kV maximum for the 833A.  Some folks
are using around 7kV or more, but I'm not sure how they get
away with that.  I tend to get internal tube arcs when I go that
high on the voltage.  A lot depends on the coil design and how
it loads the tube and how it's biased, the amount of grid feedback, etc.

It's not clear to me how you obtain 2kV when using the doubler?
Are you using a different MOT with only a 1kV output, which then
gets doubled to 2kV?

If the new triode has a graphite plate (rather than sheet metal plate),
then it should be even better.  Graphite plates can be pushed to
much higher power levels than sheet metal plates.  The spec sheets
say don't let graphite plates get red because they may out-gas,
but I let them get red anyway.  I haven't had problems with
out-gassing....yet.

Cheers,
John

 

 


 

 

-----Original Message-----
From: Teslalabor <teslalabor@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Sat, Jan 15, 2011 9:38 am
Subject: Re: [TCML] Is this 2,3kW Triode suitable for a VTTC?


Hi John,



thanks! Think I will buy a TB5 Tube. Then I will use my 5,4kV plate 

transformer + voltage doubler maybe.

By the way, my VTTC only runs with the voltage doubler properly (1 MOT + 3uF 

cap + diode).

I tried to feed the VTTC with AC only from a MOT but the output is very 

poor. This means, the sparks are much longer when fed with 2kV from the 

doubler instead of 2kV from a MOT. What am I missing? Is it due to the 

shunts in the MOT and the caps in the doubler deliver some sort of pulsed 

power to the coil?



Regards

Stefan





 
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