On 3/25/2013 12:42 AM, Jim Hoge wrote:
Today I discovered that I have had environmental ingress beneath the outer
jacket of some ~8 year old LMR-400. What I saw was a white powder like
substance between the woven shield and the foil. Also, the foam dielectric had
become hard as a rock. The length of hardening appeared to be on par with what
I have seen in 213 type coaxial cables with regard to the funky green goo that
was once the dielectric. I have other LMR cables of similar age and it is
assumed in like condition. I have the stock to make up new cables and will do
so. While I haven't noticed a change in their performance, perhaps because of
the slow degradation process, I wonder just how bad they really are. Besides
weatherproofing issues, any comments?
I have some (about 1500 feet) that's been up around 10 years now. It
hasn't shown any deterioration according to the VNA , but I wasn't
checking for small changes. My LMR 400 and 600 has always been stiff as
a board.
The UF versions OTOH were quite flexible, but exhibited bad/major
deterioration in less than 6 years. As the jacket had deterioration,
but still appeared to have integrity, I thought It might have become
porous, but that may not have been the case
I have some fairly new LMR 400 and 600 as well as the UF versions. I'll
try to remember to get some base line figures on both and compare them
with some that is about 4 years and 10 years old.
73
Roger (K8RI)
73,
Jim W5QM
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