On Mon, Jul 28, 2003 at 10:17:46PM -0400, Pete Smith wrote:
> At 06:26 PM 7/28/03 -0700, you wrote:
> >A better choice than RG-142 would be RG-400, which has the same
> >dimensions and teflon dielectric, but instead of copperweld has a
> >stranded center conductor (as does RG-303), making it easier to wind on
> >a toroid and much less likely to cause cold flow displacement of the
> >center conductor in the dielectric.
>
>
> Copperweld? RF Connection describes the center conductor as silver-plated
> solid copper, 18-gauge. With the teflon dielectric, is cold flow really an
> issue? I know it is with foam, but thought the harder plastics were
> probably immune.
Dunno. Since "RG" no longer implies mil-spec, perhaps some
manufacturers have switched to solid copper for non-MIL-C-17 products.
The Belden catalog shows silver-plated copper covered steel (Belden
#83242).
Another concern is that a copperweld center conductor will fail much
sooner than stranded copper if subjected to repeated flexing. I
discovered this while running a life test on RG-142B/U feeding a moving
antenna for a missile application several years ago (which led to
switching to RG-400).
Bob, N7XY
Teflon may cold flow less than foam, but it is still a concern.
>
> 73, Pete N4ZR
> The World HF Contest Station Database was updated 17 June 03.
> Are you current? www.pvrc.org/wcsd/wcsdsearch.htm
>
>
>
--
Bob Nielsen, N7XY n7xy@n7xy.net
Bainbridge Island, WA http://www.n7xy.net
IOTA NA-065, USI WA-028S
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