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Secondary Frequency(fwd)
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From: Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Thursday, August 20, 1998 3:59 PM
To: Tesla List
Subject: Re: Secondary Frequency(fwd)
Hi Chris,
> From: chris.swinson [SMTP:chris.swinson-at-zetnet.co.uk]
> Sent: Wednesday, August 19, 1998 7:49 AM
> To: Tesla List
> Subject: Re: Secondary Frequency(fwd)
>
>
>
> SNIP
> >
> >L is affected by the radius of the coil (geometry) as the radius is used to
> >calculate the inductance where L=(R^2 x N^2) / 9R + 10H, here R=radius,
> >N=number of turns, H=height. This is known as the Wheeler formula.
>
>
> Sod this mate, Its wrong some how. Many people have got the same calculated
> results as me but to my actaul coil measured a lot less. My coil was
> suppoed to be about 39mH but actual measurmet showed about 8Mh. I have done
> many other coils, all are wong to the above calculation. I don't calculated
> anything anymore, I just measure it all now, and wha tI carn't measure I
> guess at ;-)
A lot of people have put a lot of time into investigating formulae
that *do* work well. A disparity like that (I presume you meant 8mH?)
means you should be suspicious of your calculation, measurement or
both. I use Medhurst and Wheeler to design new coils and cross check
measurements on existing ones and they are good to well within 10%,
often well less than 5% if measured with good isolation.
Malcolm