[TowerTalk] Steel Shield on Coax

[Jan & Del Seay]

A question was asked if steel outer shield was better than copper for
shielding purposes.  No one answered so, I guess i have to show my
ignorance again.

No - for rf purposes, steel is not a better shield - but! (The caveat)
If your tv interference was "Common-Mode", and from your description,
I would assume it was, then yes, steel could in fact improve the
interference problem.  Steel is a ferrous material and copper is not.
Steel will convert rf to heat, and dissipate by convection. So, any
rf present on the shield is quickly removed. However, don't use steel
shield on you transmission lines for the radio.
I read the comments on the F-Fittings, and - he makes hundreds so
he has a good feel for what works in his industry. But - since he is
dealing with set parameters, short runs, fixed rf levels and a very
forgiving load on the end, it works. I'm sure if you looked at his
coax runs with a TDR, you'd find some real garbagy looking stuff, tho. 
What works for CATV, doesn't necesarily work for ham radio.
de KL7HF


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