Re: Redesigning/tuning a coil

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

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 


The 25-30 turns is a max.  You set your primary tap on each turn starting at
around 3 and going outward.  Some experimenters put on, example 12 turns
max, and then can't get their coil in tune because it needed 14 turns.
Without the turns available to check tuning beyond their 12 turns they never
know why their coil isn't working properly.  By using up to 30 turns you can
tune almost any cap value.

I wanted to bring this to the attention especially for new members.  I seen
many posts with someone saying I have "10 turn primary" and then having
difficulty finding a proper resonant point and poor sec output.  All the
time they are stressing their caps and NST by trying to force resonance.
Then they turn up the variac all the way and, of course, stress everything
even more.

Then, after you find the proper tune point, you add small amounts of
capacitance while reducing the the inductance.  Final goal with NST (to
provide proper impedance load and medium RF current in the LC circuit) is
10-15 turn range on primary.

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, April 17, 2004 8:34 AM
Subject: Re: Redesigning/tuning a coil


 > Original poster: pepperman-at-SoftHome-dot-net
 >
 > Thanks for the suggestions--it sounds like using a sloped primary is
 > more complicated than I thought, so I think I'll go ahead with the flat
 > primary.  It sounds like it'll have plenty of coupling anyway.  I also
 > appreciate the ideas for the spark gap and short run times to keep
 > the caps cooler.
 >
 > Dr. Resonance, I'm afraid I didn't understand what you were
 > recommending with testing the primary--you said:
 >
 > "Also, a flat test "scrap wire" primary with 25-30 turns can be quickly
set
 > up with some slotted scrap
 > cardboard for a quick test of your entire tuning range.  Keep your
sparkgap
 > setting tight (under 0.100")and your variac below 30% until you find the
 > best pri resonant point."
 >
 > How would using a temporary 25-30 turn primary help find the
 > resonance frequency for the final ~10 turn primary?  Were you
 > suggesting using normal insulated wire (e.g. 12-14 AWG) for the
 > test coil--and if so, how would you recommend varying the tapping?
 > I'm afraid I don't understand what you're suggesting here.
 >
 > (To everyone): there's something else I'm curious about--how well
 > do you think the coil would run if it was tuned up to use the existing
 > 8" x 23" toroid, rather than replacing it?  I know there are more
 > ideal ratios (e.g. 5" x 20" or 6" x 26"), but how do you think the 8" x
 > 23" would perform?  Would it be too big for the 15/60 NST?
 >
 > If it wouldn't do well, what other size would you suggest for one
 > made of corrugated aluminum ducting?  Also, a related question:
 > once you've curled the ducting around, what do you use to attach
 > the two ends?  I've read some comments about aluminum foil tape
 > disrupting the normal spark pattern, so I was hoping to avoid that...
 >
 > Michael Johnson
 >
 >
 >