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First light, and a poor performance


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From:  D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent:  Monday, August 24, 1998 12:13 PM
To:  Tesla List
Subject:  Re: First light, and a poor performance

to: Steve

With small and medium size systems never start with a fixed primary of
10-11 turns.  You probably don't have enough inductance to bring the system
into tune.  Always use some scrap wire affixed to edgewise cardboard and
use 25-30 turns with a scraped tap at each turn.  Now you have a extremely
wide range of tuning options to find resonance.  After finding resonance
then you can replace this scrap wire with the exact quantity required for
proper tuning plus a few additional turns.  With this setup your main cap
value should be around .02 MFD (2.0 nF) for effective tuning.  It sounds
like you have way too much cap for this system with a 14 x 3 toroid.  The
lowest turn on the sec. coil should be at least 1 inch above the horizontal
plane of the primary coil for proper coupling -- you are way overcoupled if
you have them even, and the pri-sec spacing should be at least 1 to 1 1/2
inches.

DR.RESONANCE-at-next-wave-dot-net


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> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: First light, and a poor performance
> Date: Sunday, August 23, 1998 10:41 PM
> 
> 
> ----------
> From:  Steve Rodway [SMTP:Legion-at-legion-elec.demon.co.uk]
> Sent:  Sunday, August 23, 1998 5:44 PM
> To:  tesla-at-pupman-dot-com
> Subject:  First light, and a poor performance
> 
> Hi all,
>     Just fired up my new TC for the first time tonight, and
> unfortunately the output fell somewhat short of what I was expecting,
> I'd be very grateful if anyone could make a few suggestions about how to
> improve it.
>     The system specs are as follows.
>     Power supply, 11 kV (rms) polepig with resistive ballast made of 4Kw
> of heating elements filter consists of 2x20mH inductors and a 1.7nF
> bypass cap. Main tank capacitor is 7.42nF and the primary coil is a 30
> degree inverse conical with 12 turns of 1 mm wire 7 mm apart. The
> primary is spaced 20 mm from the secondary and the bottom turn of each
> coil line up. The gap is 6x0.5mm tungsten carbide static gaps.
>     The secondary is 4" dia and wound to 16.5" with 0.56mm enameled
> wire, there are around 660 turns giving an inductance of 11.4mH and a
> capacitance of around 8pF.
> 
>     The system was run at first with no top load, tuning was around turn
> 6 and the maximum arc length to a grounded rod was 8", with a 4"
> spherical top load then the arcs reached 11".  When the system was run
> for any length of time, the nickel coating on the top load was etched
> through, and when the plastic underneath was burnt then the arc length
> decreased dramatically. Also it was found after a short while that the
> acrylic support structure of the gap had melted.
> 
>     I am planning tomorrow to build a much better gap that can take the
> heat for longer and a finite element array toroid 14"x3". that should
> bring the system to 1/4 wave operation, and, I hope increase the output
> because from looking at other's coils, 11" from 4Kw seems very poor.
> If anyone else has any other suggestions for improving the system, I'd
> really like to hear them.
> 
> 
>                                         Steve
> 
> --
> **********************************************************************
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> *Tel. 0973 480 692                             *     coroner....     *
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> 
> 
>