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"The Mighty Corona Cone"
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From: Chuck Curran [SMTP:ccurran-at-execpc-dot-com]
Sent: Wednesday, February 11, 1998 6:39 PM
To: Tesla List
Subject: Re: "The Mighty Corona Cone"
Hi Steve:
Your secondary dimensions are close to my unit that is 15" dia. x 56". I
use a 10 1/2" x 56" toroid whose centerline is 12" above the top turn of the
secondary. I have not seen any discharge in the top turns at all--so far!
I would suggest that you may need to make a larger toroid, if your system
has the power to handle something like 40"-60" in diameter. The larger
toroid will provide better shielding for the top turns and should reduce
breakout around the top turns I believe. It would help to have more detail
on your coil design--maybe I already missed that? I ran through several
checks on the resonance of your secondary bare and with toroid similar to
yours. I would "estimate (guess)" that the toroid provides an additional 18
pf which would suggest that your secondaries resonant point of 134 Khz would
drop to around 101 Khz--I'm curious why you indicated yours is 119 Khz with
toroid, pretty big difference. A little more system detail instead of my
guessing would make for better feedback. Did you run the wire from your
secondary all the way up and connect it to the toroid?? Don't mean to
offend you, but I gotta ask. Hope this is worked out quickly for you,
sounds like a real nice coil.
Chuck
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: 'Tesla List' <tesla-at-pupman-dot-com>
Date: Wednesday, February 11, 1998 3:41 AM
Subject: "The Mighty Corona Cone"
>
>----------
>From: SBJohnston-at-aol-dot-com [SMTP:SBJohnston-at-aol-dot-com]
>Sent: Tuesday, February 10, 1998 3:41 PM
>To: tesla-at-pupman-dot-com
>Subject: "The Mighty Corona Cone"
>
>
>Hi list:
>
>I added a 17" dia toroid made of 4" aluminum duct to the top of my 16" dia
> 48" long secondary, yet the top few turns are still streaming with corona.
> In fact, the effect may be stronger with the toroid than without. It is a
>solid, sharply-defined, glowing vertical cone streaming up and away from
the
>coil and topload.
>
>Using my URM-25 signal generator with Hi-Z output and built-in VTVM
indicator
>(perfect for this job!) I measured the secondary's resonant freq as134 kHz
>bare and 119 kHz with the top loading. My 11-turn primary is resonant at
>about 116 kHz with my 0.018-0.020 uF tank cap, so it should be tuned OK. I
>distrust the primary measurement to some degree, as I would expect the
>resonance of the secondary to affect the primary .
>
>Breakout was suppressed with the toroid in place until I used an inch of
wire
>to encourage the discharge out the side. The strikes and streamers from
the
>toroid were only slightly stronger than with just the top insulator bolt or
a
>vertical wire as top terminal.
>
>As I increase the input voltage, the corona from the top few turns of the
>secondary increase proportionally more than the streamer and strike length
>from the top terminal. Before I redesign the exciter for increased
output,
>it looks like I need to supress this wasteful discharge from the top turns
of
>the coil.
>
>Initially, I mounted the toroid directly on the top of the six inch ceramic
>insulator. This placed the bottom of the toroid within a few inches of
the
>top of the coil. I raised it up at least 8 inches higher on a feed-thru
>insulator stud - no difference, I was still running "The Mighty Corona
Cone".
>
>
>Short of submerging the entire coil in mineral oil, any suggestions?
>
>Steve Johnston
>
>sbjohnston-at-aol-dot-com
>
>
>