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Re: Propagation velocity in long helical coils.

Hi Terry,

I can now include end effects because I have solved the boundary problem but
I don't have an equation for the end C (except  Med).  However the method
could be included in your program but it would need FFT routines.  It would
have the advantage I think of accurately predicting the output voltage and
coil profile voltage (for long coil).  The later would be useful for flash
over prediction at the lower end.  It is also valid for shorter coils until
internal self C starts to produce errors. i.e. insight into current
profiles.
This method could have internal C added then it would be valid for very
short coils.

-----Original Message-----


>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
>Hi Bob,
>
> Sorry about not getting back to you on all this.  With the holiday, list
>problems, work....  I just didn't get to it.
>
>I guess the equation you found for Fo from your May 10th post is:
>
>Fo = 1 / (4 x SQRT (L x C))
>
>Where C is the "true" capcitance of the coil with the top and bottom
>shorted (no resonance).  Is this correct?

Yes but thats just a method of reducing errors caused by the ac of your C
meter.  any accurate method will do.

> I will set up a ground plane and


The equation is for an isolated coil.  But its always best to do things
above a definitive ground plain even so called isolated tests  i.e. as far
as
you can get from the plain but note the distance, correction may be possible
later.  The ground connection  to the coil should be via a thin wire (The
medhurst method).  Ideally two more measurements  on the ground plain and
one half at half max height. Then we get a measurement of the ground f
shift.

>try to do this test in a large room to get an accurate true C measurment.
>I am still doing some left over poly cap work tonight but I'll try this on
>my two well known coils ASAP!
>
>Cheers,
>
> Terry
>
>
>At 01:16 PM 05/15/2000 -0400, you wrote:
>>Hi all,
>>
>>I am surprised that nobody has checked  my equation against a coil and
then
>>posted the results, not even Terry?
>>
>>I am still  trying to do some analysis on the end effects to get an
estimate
>>but not much success.
>>
>>Regards Bob.
>>

Regards Bob