RE: Toroids

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Terrell Fritz <terrellfone@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Jim,

PIRANHA-II can make "very good" use of an adjustable top load!  The 
primary is pretty well "fixed" hiding in its "bunker" and not meant 
to be "tuned in" ever again at that point (just like Cheney >:O))...

http://drsstc.com/~piranha/PrettyPictures/Construction/PIRANHA-Const-012.JPG

http://drsstc.com/~piranha/PrettyPictures/Construction/PIRANHA-total-02.JPG

The primary coil was chopped down step by step until the right point was found:

http://drsstc.com/~piranha/PrettyPictures/Construction/PIRANHA-Const-004.JPG

http://drsstc.com/~piranha/PrettyPictures/BallTerminal/Tuning.JPG

The balls just slide in and out on the brass tubing from the hobby shop:

http://drsstc.com/~piranha/PrettyPictures/BallTerminal/TerminalTuning.JPG

This varies the coil's secondary capacitance from 28 to 34 pF.

http://drsstc.com/~piranha/PrettyPictures/BallTerminal/TerminalTuning.gif

Combined with the 73.63mH secondary, I can tune from 100.6 to 110.8 
kHz.  So if you can get the coil's tuning pretty close in the first 
place, no need for primary tap adjustments.  I do hold the rods in 
place with a bit of tape since the balls will slide right off if 
tipped otherwise.

Adjustment is useful in say going from an enclosed room to 
outside...  Instead of moving the primary tap around for the best 
arcs, you just slide the terminal ball in and out for the best arcs...

The ball terminal works pretty good:

http://hot-streamer.com/temp/DaveBaehr/b01_2858.jpg

They really are much like a conventional torroid:

http://drsstc.com/~piranha/PrettyPictures/BallTerminal/newcoil-00.jpg

http://drsstc.com/~piranha/PrettyPictures/BallTerminal/newcoil-01.jpg

I really don't think I will ever plane on using anything "else" 
now...  In order to save lab space, I think I will just "crush and 
discard" my old big dryer duct toroids since this new terminal is 
pretty universally useful for all my coils now.  I guess I consider 
dryer duct and aluminum "real" toroids "obsolete" and far too expensive now...

I do note that at lower indoor power levels, I have to use a breakout 
point or it just sits there and glows...

http://drsstc.com/~piranha/PrettyPictures/BallTerminal/PIRANHA-DragonsGlowing.JPG

The dragons and all exposed metal ,like the handles, are fully RF 
grounded...  Sort of a "hidden" strike ring...

Cheers,

        Terry


At 06:09 PM 2/28/2007, you wrote:
> Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
>
> Hi Terry, et al,
>
> There's no rain on the parade. The PIRANHA II is a work of art as well as a
> technological innovation!
>
> Perhaps a better route would be to use dyer duck to bring the coil up, and
> as time allows build the adjustable ball top load. Do you feel it needs to
> be adjustable at this point? I am looking at using 6" OD Lexan or
> Polystyrene. Is there any value to wind to 24" and add a little more
> inductance to the primary?
........