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

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

Original poster: "Loudner, Godfrey by way of Terry Fritz <twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>

Hi Shad

Welding transformers usually have cores that are held together by welded
seams. You can cut through the welded seams easily with a hacksaw or an
abrasive disk. If you can get hold of a big arc welding transformer core
that has an E with an I on top, you can cut through the welded seams to get
the I off the E. Then take several butter knifes and split the E down the
middle. Place the open ends of the two E's together for a big core. After
the coils are placed on the core, you can strap a metal belt around the core
to hold the two E's tightly together. I have held such cores together with a
piece of wood on the top bolted to a piece of wood on the bottom. Thick
hardwood like maple does a good job. As for your VTTC questions, I know
nothing about tube coil. But it seems to me that you would have to get one
heck of an expensive tube to process 5000 watts. 

Godfrey Loudner  

> -----Original Message-----
> From:	Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent:	Thursday, November 15, 2001 5:53 PM
> To:	tesla-at-pupman-dot-com
> Subject:	Push-pull Tube coil First Light, Plate transformer. 
> 
> 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
> 
>