Re: Coil behavior

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Mddeming@xxxxxxx 

In a message dated 10/22/06 12:28:21 A.M. Eastern Daylight Time, 
tesla@xxxxxxxxxx writes:
My question is can I adjust anything besides adding extra turns to
the primary? Can I use a smaller toroid, raise/lower the secondary or
raise/lower the topload? I really don't want to re-build the
primary.  JavaTC says I should be tuning at 13'ish turns. I tried 13
and get nothing but a safety gap arc. I know I'm doing something wrong.


Transformer: 15/60
Primary: 15 turns of 1/4 copper tubing.  (including Tap lead.)
Secondary : 4" and 23" of actual coil on a 25" form. (first turn
level with primary, maybe a hair above)
Toroid: 4x19 sitting at 25" high.
MMC:  .0093uF  (Ya I know I'll build another one)



Hi Glen,

    I think you have diagnosed the problem pretty well. The Fres of 
the secondary is lower than F res of the primary. You need to raise 
the frequency of the secondary or lower the frequency of the primary. 
If you don't want to add to the primary coil then there are only a few options:

1) Increase capacitance of MMC.
2) Decrease the capacitance (size) of the topload

In your specs list you left out some critical numbers -
How many turns of what size wire on secondary?
What is the spacing between turns on your primary?
Is your secondary 3.875", 4.00", 4.125" or 4.25"? On small coils this 
makes more difference than large ones.
With more precise numbers I think you'll find predictions match 
reality more closely.

Hope this helps,

Matt D.