Re: More Coupling...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Paul, 
  

Tesla list wrote: 
>
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <paul-at-abelian.demon.co.uk> 
> With secondaries, we would ideally like a count of turns. If we have 
> to estimate turns by whatever means, the utility of the measurement is 
> reduced.  This is the case with most secondaries, the exceptions being 
> those wound by machine. However, the accuracy wrt secondary inductance 
> is not an issue, so I'm quite happy to tune the turns value to match 
> (via Nagaoka) a low frequency inductance measurement.

Agreed. 
>
> > Of the coil data thus far, Marco's is mostly a guess as I don't have 
> > all the information. 
>
> The secondary inductance discrepancy is yet to be resolved. Does Marco 
> have considerable eddy loop coupling, or has he actually got fewer 
> turns than specified? 
>
> >From tssp records, I have for Thor: 
>
> Primary Coil Inside Diameter (IN) (wire center to wire center) 21.5750 
> Primary Coil Wire Diameter (IN)   0.3150 
> Primary Coil Wire Spacing (IN)  (NOT center to center) 0.8700 
> Primary Coil Number of Turns   9.5000 
> Height above ground  39.527" 
>
> Marco on his coupling measurements page reports 9 turns used, but 
> his inductance seems to be commensurate with the full 9.5

Yes, I found 9.5 is what appears to be correct as well. But only Marco can
answer that. I have sent Marco an off-list request for specs. 
>
> Why not measure from the start of the inner winding across the 
> axis to the diametrically opposite point, which is at a radius of 
> R1 + pitch/2, where R1 is the desired radius of the start of the 
> winding. Then your ruler is measuring 2R1 + pitch/2.

Ok, this is exactly how I measured which is good. I guess the point I was
attempting to make is that if the coil is wound slightly distorted, the calc
will also be distorted as they assume a perfectly round shape. Therefore, a
ruler measurement may or may not be a correct input into acmi or other program.
But as you pointed out, moving 90 deg. won't resolve this as the diameter grows
with each degree. 

I guess the best we can do is to measure ID from the start and OD from the tap
and go with that. It's difficult to take an oblong shape into consideration.
Possibly it's not a big factor. 

Take care, 
Bart