Re: Primary construction

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

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Hi MCP,

You are correct, 750kHz is "not" correct (the 14:1 h/d is outsideMedhurst 
of which this old version uses). The new JAVATC v.10 has been in testing 
for a few months. I guess it's time to let ALL the List members take a 
crack at it. It is "radically" different. The new version now uses Pauls 
GEOTC as it's core functions, just as Fantc does, but this is more of a 
design program where Fantc is more of a tool for running 
inductance/capacitance/Fres analysis.

JAVATC v.10 is probably the most advanced online TC design program at this 
point in the game. The down side is that it is pc intensive, meaning on my 
900MHz Gateway, Windows98, IE6 browser, most runs take from 30 to 45 
seconds to complete. A 450MHz would take twice as long (everything else the 
same).

Here's the link for those who would like to check it out:
http://www.classictesla-dot-com/javatc/javatc.html
I'll try to replace the old version with this new version sometime this 
week (at that point, it will be available directly from the website). This 
will probably be the last version of JAVATC I write, but I will update this 
version as necessary.

Be aware, Internet Explorer 6 is almost a "must have" with this program. 
There's a lot going on in this version. READ the "Application Notes" before 
using (it's short and sweet).

MCP, you've drastically added capacitance, thus, tank inductance will need 
to decrease meaning less turns (remember that relationship).

I ran your coil with the new Javatc.
Unloaded (no top terminal) with coil sitting on the ground = 2,906 kHz 
(yes, it's that high, no crack).

Ok, now with primary C at 6nF (0.006uF), you would expect L at 0.5 uH (yes, 
it's that small, no crack here either).

Now, placing the primary in position adds C between coils and is felt by 
the secondary.
Unloaded Fres now = 2,892 kHz and this value is based on using 0.375" 
copper tubing w/0.375" spacing (e/e) when the coil is tuned, which happens 
to be at 1.72 turns. In otherwords, the primary spec to tune using the 
copper tubing (you mentioned you had) would be 5" diam., helical, height at 
1.261" (center of wire), 0.375" spacing, and 1.72 turns.

Try a primary at 1.75" tap (unused turns will only add C  to the secondary 
and lower Fres). For example, if the same wire size and spacing were wound 
for 4.67 turns (which is the value of 3.5" (center of wire) height), Fres 
would drop to 2,823 kHz. Granted a small change in comparison to the high 
frequency, but the effects are felt back in primary.

I personally would "not" use the 0.375" size tubing on this tiny coil. I'd 
probably just use some stranded heavy gauge wire or maybe 0.25" 
refrigerator tubing. For tuning purposes, use something stranded if you can 
(keep it simple). If you keep the dimensions close with smaller wire size, 
your inductance and tune point won't change much. I would say the coil will 
tune between 1.5 and 2 turns. If your still having problems, I would be 
concerned with the cap value (make sure you measure it if possible). If you 
don't have a meter, run down to RadioShack and use one of theirs. Don't be 
afraid to tap it down to 1 turn during the tuning process. If you add a 
topload of some type, try to model it in the "new" version of JAVATC.

By nature of this coil, everything around it (moving it here and there) 
will affect the tune point.

Good luck,
Bart
(PS. Keep us updated, good or bad. I'm obvisously interested).

Tesla list wrote:

>Original poster: The MCP <ejkeever-at-comcast-dot-net>
>My two new TDK caps arrived today, meaning that I now have 6nF/40Kv of tank
>capacitor. However, this obviously throws the old setup completely out of
>whack. I've been trying to get resonance again, but failed miserably.
>
>So, here are the specs:
>Secondary: .75 inch dia, 10.5 inch wound, 1000 turns, 196 feet of 32 gauge
>wire
>Primary is helical, 5 inches in diameter, with 3.5 inches vertical to work
>with
>Tank caps are 3 X 40Kv/2nF TDK caps, X-fmr is 5000/20 NST.
>
>I've tried using JavaTC at classictesla-dot-com, but it's not working. After
>giving up in it, I tried using 2, 3, 4, 6, 8, and 13 turns, none of them that
>much better than the other. I've got more 22 gauge wire than you want to know
>about and about 10 feet of .375 inch copper pipe to work with. HELP ME,
>PLEASE!
>
>PS, JavaTC says the coil resonates at 750 Khz. Is it on crack?
>
>
>
>