[TowerTalk] RF resistance of copper oxides

[David Gilbert]

Agree about the concern for connections, but I still say you're making a 
bad generalization ... in this case based on anecdotal evidence.  The 
green patina seen on that copper tubing is very probably highly porous 
(I have experience with it since I taught myself how to create it for a 
different project), which means it provides a very tortuous path for 
current flow that would greatly increase it's resistance beyond the 
simply bulk conductivity of whatever form of copper oxide is there.  
That would make it more like an insulator instead of simply a lossy coating.

We're probably splitting hairs here, but from a purely technical point 
of view it's not correct to say that the surface condition never matters 
except for the connections.

Dave   AB7E


On 10/14/2016 7:50 AM, Jim Thomson wrote:
> ###  KM1H used cu tubing for his .25 wave strip lines in his 144 mhz tube amp.   The cu tubing  has since turned green.   Amp was built
> a long time ago.   Zero effect on BW or PO or gain.  Amp was built > 25 yrs ago.    As long as the terminations at each end are good, you wont have any issues.
> Its when you have bad connections from corrosion or oxidization that u start having problems
>
> Jim  VE7RF
>
>