Re: More primary AC resistance measurements

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Original poster: "B2 by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bensonbd-at-boo-dot-net>

Hi Gary,
    Great measurements.  Thanks for posting them.  

    It is interesting that, in going from DC to 800 KHz, the copper tubing
(1 layer) changed in resistance by a factor of 16.23, whereas the number 14
(tight wound) changed in resistance by a factor of 11.58.  The thick copper
ribbon (0.030) increased in resistance by a factor of 53.16.  The thinner
(0.008) copper ribbon increased in resistance by only a factor of 6.51.
The number 7 litz wire increased in resistance, more than the others, by a
factor of 84.33.

    Looking at the data from yet another point of view, w.r.t. the copper
tubing (1 layer) at a median TC frequency of 200 KHz, the percentage of
resistance variation is: 0.030 copper ribbon-14 percent increase, number 7
Litz wire 25 percent increase, number 14 (close wound) solid copper-60
percent increase, 0.008 copper ribbon-40 percent increase.  Copper tubing
appears to be the better primary conductor.  The copper ribbon seems to get
better as it gets thicker.  0.05 inch thick (oxygen free) copper ribbon
might be even better than tubing??

    It would be interesting to see what a number 14 solid copper close
wound (same inside diameter as before) with 30 turns would measure.

    Your log graph looks really great.  How did you do it?
    
Cheers,
Barry

----- Original Message ----- 
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, July 14, 2002 11:14 PM
Subject: More primary AC resistance measurements


> 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
> 
>