Re: More primary AC resistance measurements

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Gary,
         The figures for the 2-layer pancake are interesting indeed. 
I note that for frequencies used for most coils it falls somewhere in 
the middle of the range. I don't think the extra turns would be a 
major factor at lower frequencies but might well come into play where 
the AC resistance takes a sharp turn upwards. I suspect that we're 
seeing increased proximity effects which would probably go hand in 
hand with increased internal coupling. It would be interesting to see 
how Rac compares with *dynamic* gap resistance (not some average 
equivalent).

Regards,
malcolm


On 14 Jul 2002, at 21:14, Tesla list wrote:

> Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Gary.Lau-at-hp-dot-com>
> 
> A couple weeks ago I published the results of a series of AC resistance
> measurements of various primary coils.  Many interesting things were noted
> and several questions arose as a result of those measurements.
> 
> I have just completed a second series of measurements on some new coils.
> The new coils were a pair of space and close-wound solid #14 gauge coils, a
> two-layer 1/4" copper tubing coil, and a .03" x 1" copper ribbon coil.
> 
> The .03" ribbon performed well, but not as well as the 1-layer copper
> tubing, perhaps due to a shiny finish on the tubing but a dull brown patina
> on the ribbon?
> 
> The 2-layer tubing coil performed very poorly, particularly at higher
> frequencies.  I'm suspecting that the unused turns at the end or each of
> the two coils was a factor here, and another series or test coils and
> measurements will be needed to investigate this.
> 
> I was surprised that the close-wound #14 coil was marginally better than
> the space-wound coil.  I would have expected the proximity effect to have
> made the close-wound case worse, but apparently not.
> 
> I'd like to again thank D.C. Cox at Resonance Research for the generous
> donation of the copper ribbon.  Now all's I have to do is apply a generous
> amount of elbow grease and polish it up.
> 
> Full data, photos, and graphs may be seen at:
> http://www.laushaus-dot-com/tesla/primary_resistance.htm
> 
> Regards, Gary Lau
> MA, USA
> 
> 
> 
>