Re: AC wire resistance with proximitry effects

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Terry,

I'm sure you posted this at some point. But like everything else, it 
only becomes relative during a discussion. Forgive us. ;-) .

The original was in Dec. of 1995.

The subject title was: Coil Formers. I'm not sure any of this helps 
you out if Malcolm sent an updated file to you recently.

Here were the contents of the original (just in the event it helps 
you sort through the hash).

Take care,
Bart

-------------------------------------------------------------------------------------------

COIL MEASUREMENTS
*****************
(a)  Coils of varying h/d ratio. (frequencies in kHz)

NB - frequency has been rounded to the nearest 1kHz so the tables could
    be fitted in a reasonable space.

COIL1            |     SPHERE          |            TOROID
     | NO TERM  |                     |
Height|          |   0.7"   |    7.0"  |   0.7"   |    7.0"  |   17.3"
---------------------------------------------------------------------------
h/d   |   f   Q  |  f    Q  |  f    Q  |  f    Q  |  f    Q  |  f    Q
---------------------------------------------------------------------------
5     | 190  351 | 159  300 | 149  317 | 179  299 | 128  290 | 121  269
4     | 224  393 | 184  347 | 172  318 | 152  292 | 146  316 | 138  286
3     | 276  389 | 221  356 | 205  341 | 178  301 | 171  323 | 163  291
2     | 367  353 | 284  326 | 262  339 | 222  288 | 216  322 | 207  283
1     | 600  285 | 438  267 | 401  299 | 330  233 | 327  261 | 316  256
0.56  | 890  182 | 644  220 | 587  243 | 476  208 | 477  227 | 465  226
---------------------------------------------------------------------------
h/d = 4  with bottom turn 13" off floor : f = 222, Q = 363

h/d   | 0.56  |   1   |   2   |   3   |   4   |   5
L (mH)| 4.02  |  9.0  | 20.75 | 33.2  | 45.6  | 57.45



COIL2            |     SPHERE          |          TOROID
     | NO TERM  |                     |
Height|          |   0.7"   |    7.0"  |   0.7"   |    7.0"  |   17.3"
---------------------------------------------------------------------------
h/d   |   f   Q  |  f    Q  |  f    Q  |  f    Q  |  f    Q  |  f    Q
---------------------------------------------------------------------------
5     | 186  286 | 169  232 | 145  227 | 176  234 | 125  204 | 118  178
4     | 220  329 | 205  233 | 168  258 | 149  225 | 142  225 | 135  204
3     | 274  351 | 216  292 | 201  275 | 174  232 | 168  243 | 160  231
2     | 371  399 | 280  325 | 259  307 | 219  237 | 213  266 | 204  239
1     | 605  451 | 433  336 | 397  325 | 326  237 | 323  271 | 312  256
0.56  | 899  392 | 632  353 | 577  326 | 467  253 | 467  279 | 456  274
---------------------------------------------------------------------------
h/d = 3 with bottom mounted 13" off floor : f = 272, Q = 339

h/d   | 0.56  |   1   |   2   |   3   |   4   |   5
L (mH)| 4.2   | 9.05  | 20.7  | 33.1  |       | 56.6

NOTES: I forgot to get inductance reading for h/d=4 for Coil 2 :(
    : A reality check on Coil 2 (h/d=1) Q reveals that the resonant
      frequency measured is within 1% of that calculated using the
      measured inductance and Medhurst's self-capacitance formula.
      The Q gives an AC resistance of around 75 Ohms including the
      generator and coax and strap used to feed the coil. The clear
      message is : If you are using 100 Ohms+ in series with your
      coils to measure them, you are not doing them justice.
    : One final note; I only recorded the data at the time of measurement
      and did not calculate BW and Q so my judgement would not be
      clouded by seeing the results. I consider the results to be
      entirely consistent with well established theory. On the basis
      of these results, I have wound two coils on these formers for
      powered use, one close-wound using 0.9mm wire and one spaced
      using 0.56mm wire with a wire/pitch ratio of about 0.5.


Tesla list wrote:

> Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
>
> Hi,
>
>
> > I recently bundled all the measurements I made up in one file and
> > sent it to Terry to put somewhere on hot-streamer (Terry ? please ?)
>
>
> Ohh oh!!  There are like 3 gig of files...  Give me "at least" a 
> little hint ;-)  Date, a guess at the file name, first letter and I 
> can sort by recent dates...  I get 250 E-mails a day...  I sort of 
> remember this, but I can't remember the file... #:-)
>
> Cheers,
>
>         Terry