Re: Ross-O's VTTC update

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

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 1/22/01 10:13:36 AM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

> Need to figure out:
>  (1) grid circuit still not optimal.  I(g) is looking more reasonable but 
the
>  coil still won't run good unless I completely short the grid leak C.  See
>  page for more details.

Ross,

I looked at your page.  One thing that may help tremendously is
to increase the plate supply voltage to about 3500 volts or so,
and increase the grid leak resistance.  You may be keeping
the tube on for a wide conduction angle to compensate for a 
low plate voltage.  Greatest efficiency occurs with high plate
voltage and higher grid bias, for a small tube conduction angle.
This will allow the tube to handle a lot more power without
getting any redder.  Voltage is the key to these VTTC's.

It's also possible that you have too many primary turns, did
you say you have 38 turns?  If so, this also will demand a
low grid resistance to force the tube to stay on long enough
to pass enough power.  Tank impedance is quite critical on
these things.  

When you change one thing.... it tends to affect everything
else.  So if you change just one thing.... the coil may seem
to be getting worse, but if other changes are made, then it
may become overall better.  These are tricky beasts.

John Freau