Home Made Ladder Line

[wb1aij]

Looking for advice on home brewing some open wire ladder line; I was planning on using single conductor # 12 insulated copper from Home Depot. I found an online calculator that computes skin effect at whatever frequency. It is telling me that 30 mhz my #12 wire has the same DC resistance as a # 38 wire. I don't like that at all!!!! Has anyone out there had any experience in this? What about the plate tank circuits in all of our medium & high power transmitters? That is single conductor wire at high frequencies.

[KF1Z]

Insulation has an effect on "skin-effect" / velocity factor.

Not sure if the program took that into account...?

[w4bfs]

I would like to examine this program .... seems to not be accurate .... there is some confusion about surface area and circular mils ....be careful ...73....John

[WD8BIL]

http://amfone.net/Amforum/index.php?topic=18726.0

[wb1aij]

Here is the calculator that I used; http://daycounter.com/Calculators/SkinEffect/Skin-Effect-Calculator.phtml
After calculating the depth of current penetration @ 30 mhz (.518 mils) I calculated the area of 2 circles; the total area of the wire and the area of the interior of the wire below the depth of current penetration. Taking the difference gives me the area of the wire where current flows & that comes out to 65 C.M. This converts to a wire with a diameter of about 9 mils or AWG 31. What am I doing wrong?

[KF1Z]

Well, the DC resistance of the wire is the entire area of the wire.... right... ?

I think you're confusing AC (rf) resistance with DC resistance.

Could be wrong.... 

[wb1aij]

Well, the DC resistance of the wire is the entire area of the wire.... right... ?

I think you're confusing AC (rf) resistance with DC resistance.

Could be wrong.... 

The way I understand it is that at 30 mhz the AC resistance of my AWG 12 wire is the same as the DC resistance of an equal length of AWG 31 wire.