[TowerTalk] 80 Meter yagi question

[Richard (Rick) Karlquist]

On 10/12/2017 12:26 PM, Jim Thomson wrote:

> 
> ##  are u sure about that ?   K6STI coil software doesnt depict that effect.  Nor does other software.... unless they
> are both wrong.   I also used Termans equations..and did it by hand.   They all concur.   This was calculating ESR.

Yes, I am sure.  See:

http://www.americanradiohistory.com/Archive-Handbooks-Miscellaneous/Federal-Reference-Data-Radio-Engineers-4th-1956.pdf

Page 131, Equation 2.  "Rho" is inside the radical.  "AC" (meaning
RF) resistance is proportional to the square root of DC resistivity
(denoted by rho) for the material.  Rho is the greek letter that
looks like a lower case "p" in italics.

> and ID of new AL tank coil.   Did not have to touch the tune and load either, dead on.   Aluminum  coil ran hot.....  go figure.

Perhaps due to the shiny aluminum having poor emmisivity and
not radiating heat well.

Rick N6RK