* Originally By: Kukkonen-at-snakemail.hut.fi
 * Originally To: Richard Quick
 * Originally Re: RE: GIF FILES
 * Original Area: UUCPE-Mail
 * Forwarded by : Blue Wave v2.12

Date: Sat, 27 May 1995 02:43:18 +0300 (EET DST)
From: Kristian Ukkonen <kukkonen-at-snakemail.hut.fi>
To: Richard Quick <richard.quick-at-slug-dot-org>
Subject: RE: GIF FILES

On Fri, 26 May 1995, Richard Quick wrote:

<about secondary in magnifying transmitter>
> have found that an aspect ratio of about 1.5:1 on a coil form 14
> inches or more in diameter works well. The secondary coil should
> be wound with heavy wire, but since very high inductance is not
> critcal here, a heavy stranded insulated wire may be used. Magnet
> wire would likely work better, but based on the surplus prices of
> PVC jacketed stranded wire I have not found magnet wire to be

How heavy wire do you mean - something like #10 (2.588mm) or less ?

I presume that you have actually done this with a setting as described
above? What was it like - wire gauge, diameter etc?

Is the set-up above only good for power-levels of several kWatts and
above or is it good for something like 1kW as well - or should
it be smaller for this?

> The primary coil should be large and very closely coupled to the
> squat secondary coil. Heavy wraps of polyethylene plastic may be
> required between the primary and secondary to prevent arcing. I
> have found that any and every means of insulation between coils
> may well be required to obtain high efficiency in a compact unit.

What exactly did you use for the primary - heavy copper tube as
a helical coil? What was the set-up like - proportion between sec.
and pri. diameters, heights etc..

In Scientific Instruments Reviews a "few" years ago there was a 
description of a tesla-coil (in inert-gas tank etc.) that
used only one turn in the primary - a large piece of copper plate
to be exact.. I guess that it was not too efficient.. 

> on aspect ratios, a shorter coil will frequently work better than
> a longer coil designed for a 1/4 wave system. Even though the
> impedance of the extra coil needs to be larger than that of the
> secondary, too much impedance limits efficiency, yet the extra
> coil is required to resonate at a much lower frequency than the
> secondary coil for efficient systems. This is where it is really

Your ancient :) text describes that the primary and tertiary coil
are of the same frequency and the secondary is twice of the frequency
before - I guess this is the basics? 

> drastically reduced. By closely coupling the primary and
> secondary, then using a fast quenching spark gap in the tank
> circuit, it is possible for more than 50% of the peak tank

As one uses a very high break rate on the rotating spark-gap - will
one have to put in a _lot_ of power to be able to fire the cap as
ofter as it should or will one use a very small cap or ?

I have some huge fiber-glass tubes (nearly a meter in diameter) that
might be of use - they have walls about 10mm thick though.. :( but the
height to diameter proportions are about exactly correct.. :) 

Thanks for the information!

I really intend to build a system like described above..


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