Hi Brent, I agree with Skipp, the LMR is not the cable i would recomend in a duplex preeater install. If you want jumper coax, i only use RG400 and it is a plenum rated silver plated with double shield brade silver. Both Motorola and Kenwood systems use this coax for there internal cableing inside the cabinet. I yet have seen them use LMR coax. Spend the little extra for good coax and you will find yourself much happier and not searching for weird site problems. For the main feed line, you cant get any better then Andrew's LDF coax for repeater installs.
Mike Mullarkey K7PFJ -------------- Original message -------------- From: "KF4TNP" <[EMAIL PROTECTED]> RG-393/U M17/127 I use this cable in most runs in the transmitter buildings to and from each station since it has the dual silver shields, I dont have dissimilar metals to worry about. And can handle 1.8kw @950Mhz it works out great. Brent KF4TNP From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of skipp025 Sent: Saturday, May 10, 2008 12:10 PM To: [email protected] Subject: [Repeater-Builder] Re: Best coax for short jumpers in repeater cabinet? > 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
