Re: 3/4 wavelength secondaries

At 04:25 PM 7/21/96 +0000, you wrote:
>>From couturejh-at-worldnet.att-dot-netSun Jul 21 09:31:22 1996
>Date: Sat, 20 Jul 1996 16:03:26 GMT
>From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
>To: tesla-at-pupman-dot-com
>Subject: Re: 3/4 wavelength secondaries
>At 09:25 AM 7/19/96 +0000, you wrote:
>>>From sgreiner-at-wwnet-dot-comThu Jul 18 22:44:31 1996
>>Date: Thu, 18 Jul 1996 16:29:39 -0700
>>From: Skip Greiner <sgreiner-at-wwnet-dot-com>
>>To: tesla list <tesla-at-pupman-dot-com>
>>Subject: 3/4 wavelength secondaries
>>Hi everyone
>>I wonder if anyone has ever tried to wind a secondary at 3/4 wavelength 
>>rather than 1/4 wavelength.
>>It appears that it may not be possibe to wind a 1/4 wavelength coil that 
>>will resonate at the correct frequency without using the large terminal 
>>capacitance. Perhaps a 3/4 wave coil could be made.
>>I would appreciate any comments.
>Hi Skip -
It looks like you have started a new challenge for Tesla coilers. Instead of
long sparks it now is 1/4 wave etc. coils. It appears that there have been
many coils built that work without large secondary terminals but the
frequency did not meet your specs.

I have been working on the problem and have obtained the possible necessary
coil parameters for small coils where the operating frequency relates to a
specific fraction of the wavelength of the secondary wire length. This means
that anyone with a small budget can build them. This information has come
from the JHCTES computer program. However, these coils are beyond the limits
of the program so the sparks may or may not be all that great. The data for
sparks in the program come from regular classical coils.  

I do not intend to build and test the coils because I would have a conflict
of interest. However, if you or others are interested in the job then I will
post the data. These coils have some interesting characteristics. The
possible spark length for the 3/4 wave coil is less than for the 1/4 wave
coil. The secondary peak amps for the 3/4 wave coil is greater than th 1/4
wave so the secondary wire should be larger, etc. 

I anticipate that the operating frequency test will be the biggest problem.
Every coiler has his own method. I suggest that a standard test be agreed
upon. How do you test for this parameter? There are many methods shown in
the literature including my books. Also the spark length test should be a
horizontal spark between the secondary terminal and a ground point. The
streamers normally referred to are longer and subject to opinions. 

This research may lead coilers to a new way to look at Tesla coils and their
possible use as practical devices. The NASA tether experiment is now using
some of Tesla's ideas. They are using the ionosphere as  a conductor to
power future space stations. The large volume and minute currents needed
because of the high voltages means the losses are negligible as Tesla
pointed out. However, as Richard Hull pointed out the overall efficiency
would be low because of other conditions. Testing these coils may also solve
the problem of whether the Tesla coil acts as an antenna or as a regular
transformer except for a resonant voltage rise in the secondary. For
example, the possible distructive overvoltages along the coil. It appears
there are many possible Tesla coil secrets that can be solved.

John Couture