Re: Stainless steel tubing for primary?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Kurt Schraner <k.schraner@xxxxxxxxxxx>

Hi Tom, all,

while it would probably work, I'd not give away loss of energy, due to 
ferromagnetic properties of the material. Sometimes it may be forgotten, 
skin effect resistance not only depends on frequency, but as well on 
permeability. And you would expect a much higher primary coil RF 
resistance, which would need to be related to the gap loss. I'd just not 
torture myself for making a stainless-steel minor quality primary, when 
1/4" soft copper tubing can be bought everywhere. Here the formula for 
skin-depth:

(sorry no greek letters in plain ASCII):

Skin-depth  d = SQRT( 2 / (omega * uo * ur * k) )

resonant frequency      f
at resonant frequency   omega = 2*Pi*f

permeability constant in SI-System:
uo = 1.25664E-06[H/m] =1.256637061[uH/m]

relative magnetic permeability  ur [-]
(Ferromagnetic materials - even some stainless steels - having a much 
higher number here, ... some 10 to some 1000), meaning the skin-depth going 
down by the square-rooot of the proportion. .

Example Copper:
rel. magnetic permeability     ur       1       [ - ]
specific resistivity (20C)    rho  [[Ohm*mm2/m]  =0.01786 for copper
conductivity of conductor      k    [m/(mm2*Ohm)]=55.99104143

...Please enter the data for your stainless-steel, if available.

Cheers,
          Kurt


Tesla list schrieb:
> Original poster: "Coyle, Thomas M." <tcoyle@xxxxxxxxxxxxxxx>
> So I'm all ready to wind a nice flat primary today, and, lo and behold,
> I'm out of 1/4" copper tubing. I have a bunch of 1/2", but don't feel
> like getting arm-exercise today. I do, however, just happen to have
> about 1000ft of 1/4" stainless steel tubing in a continuous spool laying
> here.
> Any thoughts on using this for a primary?
> Performance considerations aside, I think it'd look quite cool.
> Tom