1/4 Wave Theories - do a test?
From: terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
Sent: Thursday, June 04, 1998 8:53 AM
To: Tesla List
Subject: Re: 1/4 Wave Theories - do a test?
At 08:04 PM 6/3/98 -0500, you wrote:
>From: Mad Coiler [SMTP:tesla_coiler-at-hotmail-dot-com]
>Sent: Monday, June 01, 1998 9:45 PM
>Subject: Re: 1/4 Wave Theories - do a test?
>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.
Rest assured, everyone one on this list who may be considered
"knowledgeable" has traveled a long and difficult path to get there. We
were all once "unknowledgeable" and we have no reason to be jumping down
anyone's throat just because their knowledge level is were ours was perhaps
only a year ago. All we wish is to make the path for others easier than it
was for us.
> 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?
> 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.
> Constructive critisism is welcome.
In my opinion, other factors such as quenching, coupling coefficient, and
the change in component values are accounting for your observations. I have
no data that would suggest that only the wire length being at or near the
1/4 wavelength of your coil's operating frequency would make the difference
you are seeing.
Since the output change is so dramatic, I suspect quenching, for whatever
reason, was better in one test. This is not surprising considering my
recent tests and paper on the subject. Quenching and adjusting the coupling
is very important! The way to know for sure is to use a scope hooked to an
antenna to pickup the coil's signals. That will tell you if the coil is
quenching well or not. If you did this and the quenching looked correct in
both tests, E-mail me and we can do much more to analyze what was going on.
That's my $0.02 worth.
All the best.