[TowerTalk] [Fwd: Re: LOW INDUCTANCE COPPER GROUNDING STRAP]

[Tom Rauch]

> I think W8JI posted on this one a while back, and if my
memory serves me
> correctly, the reason braid is inferior is that as it
corrodes it increases
> resistance.

Skin effect forces current to the outside surface. Since the
outside weaves into the inside, current has to flow through
the hundreds and hundreds of pressure connections. The
connections are bad enough when the braid is fresh and shiny
and has pressure forcing the strands together. They are
terrible when the braid becomes tarnished or the pressure
lightens up.

As a matter of fact this is one of the main reasons coaxial
cable goes "bad" and has high loss after moisture gets
inside.

When testing HF amplifiers in the 70's or 80's we found the
braid removed from RG8 coax had more loss than number 14 or
16 wire in ten meter tank circuit leads. Despite being
larger (meaning it would dissipate more heat) the braid
overheated to the point of discoloration while #16 wire with
much smaller surface area remained shiny.

73 Tom