From: Esondrmn [SMTP:Esondrmn-at-aol-dot-com]
Sent: Thursday, March 19, 1998 5:57 PM
Subject: Re: which disease?
In a message dated 98-03-19 00:18:22 EST, you write:
Dear All, I need some help.
I wound a coil (diam. 4.33", height 33.66") with .35mm wire (AWG 28??)
and a total secundary resistance of approx. 155 ohm. I thought that
these 790 meters from 2290 turns would give me resonance at 94,8 kHz.
Everybody talks about 3:1 ratio but that means with 10" diam
->30"height, doesn't it. How do I get 1000 turns in so little height.
Can I take a form with more height??
I now get breakouts (>20") at half of the form, distroying my turns. I
am using a cap wound from 2.5mm thick red plastic (don't know the
material) 2 plates from about 20 cm widht and 7 meters long. Primary is
7.5 turns of .5" copper tube, gap=single .5", toroids vary. Best
sparklength I get (don't understand!!!) with a very small toroid! Supply
is a 10 kv 10kva plate transformer and a variac.
is it wise to build a new coil with 8"diam and what height and number of
turns should it have??? What wirediam??? I am thinking of using wire
used in mainssupply (2.5 mm2). at least is low resistance. What am I
Please advice and thanks,
I calculate that your secondary should resonate at about 176 khz with no
toroid and about 94 khz with a 30 pf toroid on top.
Your height to diameter ratio is 7.8. With a 4.33" diameter coil, I would try
to keep this at about 4:1 maximum. This would be 17.32 " of winding length
and 1,212 turns of wire at about 70 turns per inch. You could actually make
it a little shorter and still get 900 to 1,000 turns.
If you are getting breakout in the middle of the secondary, your primary must
be tuned to a frequency that is about twice the self resonant frequency of the
secondary. It sounds like you could cut your existing secondary in half and
be right in the ball park.