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## Re: [TowerTalk] TT SHUTDOWN

 To: JC Smith ,TowerTalk Re: [TowerTalk] TT SHUTDOWN Red Wed, 12 Jul 2006 14:04:24 -0500
 ```Sri, gang; the Scot, Maxwell, and the Englishman, Heaviside, decree that RF will still concentrate on the outside of a conductor. The distribution of current in depth is an exponential function, but the effective skin thickness, in copper, is 0.0026" at 1 MHz, 0.000826" at 10 MHz, and 0.00026" at 100 MHz. Reference _Radio-Electronic Transmission Fundamentals,_ B. Whitfield, Jr. It is a semi-technical book, long out of print, that offers good explanations for the non-engineer qualified ham. It is worth searching for on the used book market. Meanwhile, copy those numbers and paste them where you can find them. When calculating the resistance of a copper conductor, don't use the cross sectional area, use the circumference times the effective skin depth to calculate the effective area of conduction. Another advantage of strap, or widely spaced wires, is reduced inductance per unit length, compared with a cylinder of similar circumference. 1994 Radio Amateurs' Handbook, page 2-20, providing the following formulae: For a flat strap: L = 0.00508b[ln (2b/(w+h) + 0.5 + 0.2236 (w+h)/b] where L = inductance in microhenrys b = length in inches w = width in inches h = thickness in inches. For a round wire: L = 0.0002b[(ln(2b/a)) - 0.75] where L = inductance in microhenrys a = wire radius in mm b = wire length in mm ln is the natural logarithm Sorry about the change from inches to mm. I'm quoting ARRL. I believe the following is correct with the dimensions in inches: L = 0.00508b[(ln(2b/a)) - 0.75] Inductance of parallel wires spaced apart approximates the inductance of parallel inductors. Their paralleled resistance is also lower than that of a single wire at HF frequency if the total circumference or surface area is greater, assuming the material is the same. 73 de WOØW JC Smith wrote: > What if >you slit the copper tube before using it, would that be enough to allow both >the inside and outside to conduct high frequency current? > > > > > _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread Re: [TowerTalk] signals on inside of a pipe.. RE: TT SHUTDOWN (was:4 awg copper wire and Amp locks), (continued)