In article ,
Highland Ham wrote:

My question is directed to the different grades K,L and M ,whether any
particular grade would give better RF radiation performance .
It could be that the grade with the highest copper content gives the
best performance ,although I doubt that it will be measurable.

My recollection is that the basic difference between the various
grades is the thickness of the copper walls. The thicker-walled pipe
is what's preferred for outdoor/buried use and/or higher pressures
(e.g. use on the supply side of a house's water-pressure regulator).

RF current flows only through the skin of a conductor... it doesn't
penetrate very far into the body. One web calculator I found says
that the skin depth of a 144 MHz signal in copper is around 200
micro-inches, or 1/5000 of an inch. If the tubing wall is
much thicker than this, the additional thickness will have no
significant benefit in reducing resistive losses.

Since even the thinnest-walled (Schedule M) copper pipe has a wall
thickness which is about a hundred times more than the skin depth,
there's no electrical benefit to using thicker-walled tubing (Schedule
K or L).

Unless there's some mechanical reason to want to use the heavier-
schedule tubing, I'd just stick with Schedule M - it's lighter, less
expensive, and should be plenty stiff and strong for most
applications.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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