Very interesting...all our sites are dense with RF from Public Safety radio
systems 800, 700, VHF, etc. No problems in five years. I suspect it has more
to do with how the RF connections are made than the LMR cable. Just my
subjective opinion of one.
73,
dave
wa3gin
----- Original Message -----
From: n...@no6b.com
To: Repeater-Builder@yahoogroups.com
Sent: Sunday, January 03, 2010 2:45 PM
Subject: Re: [Repeater-Builder] Mastr II mods and parts
At 1/3/2010 11:11, you wrote:
>Yes, it was resolved at a lot of commercial sites by not allowing it to be
>used ;-)
For me, the "resolution" came from a Times Microwave sales rep. who
admitted that LMR-400 is not appropriate for duplex use.
Having said that, you can get away with using it in situations such as
temporary/portable repeater installations provided the connectors are
installed properly & the feedline is not used near the antenna, where RF
can couple to the outer braided shield. In no circumstances would I ever
use it at a shared comm. site.
>Usually after a bit of time, the cable will start to become a source of
>noise as the two dissimilar metals start to react with each other. There
>are many documented cases of this problem. Search this group's messages
>and you'll see this has been discussed over and over. It comes up about
>every other week.
BTW, they don't need to be dissemilar metals. I once confirmed a 100%
copper braided RG-213 jumper as a PIM source. I only use silver-plated
braided coax beyond the duplexer from now on.
Bob NO6B
