Re: Vacuum Tube Tesla Coil Design (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Fri, 5 Oct 2007 09:09:31 -0700 (GMT-07:00)
From: penny831@xxxxxxxxxxxxx
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Vacuum Tube Tesla Coil Design (fwd)

Hello Martin,
  I would be interested in seeing that schematic if you wouldn't mind sending it to me.

Thank you,
Tony

-----Original Message-----
>From: Tesla list <tesla@xxxxxxxxxx>
>Sent: Oct 5, 2007 7:51 AM
>To: tesla@xxxxxxxxxx
>Subject: Re: Vacuum Tube Tesla Coil Design (fwd)
>
>
>---------- Forwarded message ----------
>Date: Fri, 05 Oct 2007 13:41:35 +0200
>From: Martin Damev <mdamev@xxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Re: Vacuum Tube Tesla Coil Design (fwd)
>
>Hello Brad,
>
>Some two weeks ago you posted something about
>building a VTTC with your 4-400 tetrodes.
>
>There is a very interesting and efficient oscillator
>circuit you could use for your VTTC. If you are
>interested I will help you with the necessary calculations.
>I'm talking of the  "push-pull oscillator with capacitive
>dividers for feedback". This design uses two 4-400 tetrodes
>but in return you get approx. twice the RF output.
>Using capacitive dividers for feedback you can avoid
>the "tickler coil" and you get better driving conditions for
>the tetrodes. The circuit may look  more complex at first
>glance, but it is not more difficult to build. Basically it
>is similar to an astable multivibrator circuit.
>
>I designed such a circuit for a coiler-friend. This small
>but very nice VTTC uses two 7843 tetrodes by RCA that we
>pulled out of some military communication equipment.
>These small tetrodes are metal-ceramic design and conduction
>cooled. The VTTC works very well though  it will need larger
>primary capacitance to take full advantage of the tubes capabilities.
>
>I personally do not recommend using tetrodes as triodes by
>connecting both grids together. First you can be sure that you will
>easily exceed the control-grid's dissipation rating in most cases
>(especially when the oscillator is not loaded). Second a tetrode
>allows you to pulse the oscillator through the screen grid voltage.
>John Freau has shown that there is a lot of potential in using this
>method.
>
>Two 4-400s should give you 25-30 inch sparks in a good an optimized
>setup.
>
>- Martin
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