> I think the LMR400 is a double shielded with each shield > different metals. One braid and one foil. This is a no-no > for duplexed repeaters for the higher TX RF will generate > noise getting into receiver.
Just to be clear... The dissimilar shield metals is the potential problem source, not the braid - foil combination. And notice I used the term "potential problem source". It's not always automatic gremlin 101 right out of the starting gate... Some years back I used a fairly large amount of LMR-400 feed line in various new radio & repeater system (applications) until I sourced more than an unacceptable number of antenna system "train wrecks" specific back to the LM-400 (and LMR-600) cable. Sometimes the problem took months and even years to develop... but from memory I've never had an installation of conventional antenna hard-line or coax feed sabotage a radio system like the many examples I've had to ferret out from or back to LMR-400. No more LMR-400 for me or any antenna system I'm involved with. The other cute dissimilar metal shielded coax problem is how physical cable movement can easily be a noise generator. There is a potential for LMR-400 coax moving in the wind to be noisy... and I have seen that demonstrated in an actual installation. cheers, skipp skipp025 at yahoo.com www.radiowrench.com
