1/4 Wave Theories - do a test?

From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent:  Wednesday, June 03, 1998 10:24 PM
To:  Tesla List
Subject:  Re: 1/4 Wave Theories - do a test?

Hi Tristan,

> From:  Mad Coiler [SMTP:tesla_coiler-at-hotmail-dot-com]
> Sent:  Monday, June 01, 1998 9:45 PM
> To:  tesla-at-pupman-dot-com
> Subject:  Re: 1/4 Wave Theories - do a test?
> Coilers,
> I am not yet the most knoledgeable on the theories of the Tesla Coil yet 
> (but I am getting there), but I have one idea about the 1/4 wave 
> conflict.  Why not just do a simple test.
>   Now - please dont jump down my throught or anything - but do tell me 
> if there is some problems with my idea.
>   Build (if you dont have on already) a Tesla Coil that is designed so 
> that its length of wire on the secondary is equal to the 1/4 wavelength. 
> This will only work if you have a larger toroid you can also run the 
> system with. Measure the maximum spark length produced by your 1/4 wave 
> Tesla Coil.  Then put a larger toroid on it that brings the frequency 
> below that of when it was equal to the 1/4 wavelength. See if spark 
> length increases. If it does increase this could mean many things but it 
> comes down to the simple fact that it worked better than it did when it 
> was equal to the 1/4 wavelength. I know that many other factors can 
> change but what does it really matter if you trying to get the most 
> spark length - and one way gives you more spark?

It matters if you are trying to determine what parameters if any are 
affecting output. 

>   For example, I have tried this. I have a small 3.5" diameter secondary 
> that has 500' of wire in it.  Running it at around 400kHz (1/4 wave 
> equals 616') it has almost double the spark length and several times the 
> power as when I run at the 1/4 wave frequency. And yes, the coil was 
> fully retuned for all experiments.

OK - you must be running it with a larger terminal at the lower 

#1 - top storage capacity is increased lowering the impedance 
delivering energy into the output discharge. More of the energy 
ending up in the secondary is on tap to feed the discharge in a 
shorter time than if it had to come from the coil itself.
#2 - if you tapped in more primary turns, primary Q is higher as gap 
loss is reduced. This can make a very significant difference to 
output in many systems. I noted exactly this by eliminating a source 
of loss in a small system last night *without retuning a thing*.
You didn't say whether spark gap settings were the same, nor did you 
say whether you increased your primary capacitance. Be interested to 
hear what exactly you changed.