Re: tubes and windings

["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 12/13/00 1:43:30 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

>  right now, i know nothing of how tubes work, or how
>  well they work on coils if you could get a nice 120 BPS. is it possible to
>  use an air or rotary gap now and then switch to a tube at later time? or
>  does the coil have to be redesigned to use a tube and its not worth the
>  trouble?
>  
>  another question, how would one go about winding a seoncardy fairly
>  easily? i intend to do it by hand, but if anyone has suggestions im open
>  to them. what do you do if you need to stop in the middle of winding? put
>  a peice or tape or putty to hold the last few windings in place or
>  something?
>  
>  thanks!
>  
>  -fox

Fox,

A tube coil uses a different circuit than a spark gap TC.  A tube
coil is more complex and is basically a power RF oscillator which
is actually an RF power amplifier with feedback.  

     http://hometown.aol-dot-com/futuret/page3.html

There's links there to my tube coil page, and a link from there
to a schematic of my coil at David Trimmell's website.  In any
case, spark gap coils are much more "efficient" than tube coils.

Of course the
same secondary and primary coils can be used with either type
of Tesla coil.  In any case, the tube does not simply replace the
spark gap.  (unless you use bi-polarity hydrogen thyratrons or 
some such scheme, but this has never been done as far as I know)
Richard Hull of the TCBOR has used a hydrogen thyratron, but it
was not bi-directional which limited the coil's output.

I use a gear motor to drive the secondary coil at a slow speed,
then I hold the wire by hand and guide it onto the form.  The form
can be held at each end by wooden uprights with a screw as a
bearing, etc.  Yes, just place a piece of tape firmly over the last
turns when you need to take a break from the winding operation.

John Freau