Re: Push-pull Tube coil First Light, Plate transformer.

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

Original poster: "R Heidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>

on 11/15/01 4:52 PM, Tesla list at tesla-at-pupman-dot-com wrote:

> Original poster: "Sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <sundog-at-timeship-dot-net>
> 
> Hi All!
> 
> Got my VTTC working beautifully in push-pull.  An O-scope with a simple
> antenna does a million times better for tuning it.  While the tuning isn't
> "dead on", it's within a few hundred hertz per side of the primary.  The
whole
> setup looks difficult to build and wire, but it's not nearly as difficult as
> you'd expect, and it has a distinct elegance to it.    I haven't run the
setup
> over a few hundred watt, due to plate transformer constraints.
> 
> Full-wave rectified DC, fed to the middle of the primary, tubes and tap for
> the MMC's on the far ends of the primary.  Grid leak connects to the
middle of
> the grid windings, and the ends each go to a tube.  Simple!  Working with the
> coil (which puts off a *TON* of ozone) is easy, and any mis-tuning in the
> primary is easily seen on the scope, and even better, heard!  When the
primary
> is out of tune, you can hear a high-pitched squall from the output.   Putting
> capacitors across the DC supply did a lot to boost output, but it also rasied
> current consumption on the mains side more than I liked. Running well-tuned,
> the output is a steady humming hiss rather than the not-so-subtle 60hz hum of
> my voltage-doubled setup.   It works, is simple, and best of all, works
> *GOOD!*  
> 
> Biggest problem I have at the moment is finding a suitable core to wind my
> plate tranny on.  I'm needing something in the 5-6kva range.  An old arc
> welder
> would be awesome, assuming I could get the core apart without ruining it.  I
> want to run the tranny off 240v and get 2500v (2800v by tapping the primary).
> With a center-tapped design that means I should have 5.2:1 turns ratio for
> each
> secondary.  I have all the parts for a suitable winding jig, I just need to
> rig
> up a turns counter and find a core.  I'm wanting in the 5-6kva range from it,
> I
> can ballast it externally if needed.
> 
> For controlling the grids externally, can I wind a step-up transformer on set
> of ferrite clamshells I scrounged from an old TV?  That way I can feed a
> modulated signal to the primary on the tranny and get corresponding output
> high
> enough to switch the tubes?  Does the whole transformer need to all be on 1
> ferrite half, or can I wind them on separate halves and use the supplied
clips
> to clamp the cores together?  Thanks!!
> 
> 
> Shad
> 
> 
> 
Winding coil windings on each half of your coil form is a common practice
providing you put the coil form together after winding. Watch your polarity
of your coil, the windings will be out of phase.
   Robert  H