Re: VTTC provisional results

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "Herwig Roscher by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <herwig.roscher-at-gmx.de>
> 
> Ed Phillips wrote:
> 
> >  That's a DC input of over 3 kilowatts; seems to me you should
> > get more out, but then I haven't built a high-power VTTC!
> 
> Ed,
> 
> But how to get a higher output? My power supply could deliver
> "endless" power and the only way might be a better match
> between the load and the tube.

	You may well be getting all the power of which that tube is capable. 
Don't have any way to judge, but notice some of the "big boys" think
your results are good for the power.

> >  Slight correction.
> - Very welcome.
> 
> > tetrode, or pentode is acting as a switch and plate resistance isn't a
> factor.
> - I have tried various primary coils from 7 turns to 67 turns (now)
> and found that the actual coil works best despite the transformation
> ratio is lowest now.  Why?

	In a coupled-resonator system such as a TC, whether spark or tube
driven, the "transformation ratio" (if by that you mean ratio of
secondary turns to primary turns) is no indication of the voltage rise
you might expect.  What does matter is that both primary and secondary
resonate at the same frequency, which may be why your "actual coil"
works best.  Have you tried varying the spacing between primary and
secondary while keeping things in tune?  That is the correct way to vary
the impedance the tube plate circuit sees.  There is one spacing
(coupling factor) which will give maximum power from the tube, and once
you have determined that you've done all you can.

> Regards,
> 
> Herwig

Ed