radiomog wrote: > All this talk of LMR cable problems. > > does anyone have any reference articles or a web site where I can delve > deeper into this subject ?
I have only ever seen the topic discussed on this particular list. If you look at the archives, you will see that it's been debated many times over the last several years. Personally, I have seen the problem and have been able to remove noise from duplex systems by eliminating these types of cable (9913, LMR-400, etc.) The problem is these cables are made from dissimilar metals, tinned copper wire over an aluminum foil braid. This situation, in time, creates thousands of tiny diodes; which relates to IMD, noise, and just plain trouble. I have had several folks email me stating they had noise on their system that couldn't seem to be resolved by standard troubleshooting methods. When asked, many of these systems used tinned braid over aluminum foil cables somewhere in the system. In *many* of these cases, the trouble was solved by replacing the suspect cables with RG-214, RG-142, Andrew Superflex, etc. LMR is fine for simplex communications, by itself. There are now several site managers that won't allow this type of coax on a commercial site, because of its poor duplex service. I was going to write an article about it but just never did... I guess I should. Kevin
