Dan Hancock wrote: > Why do you believe that double shielded cable is > necessary for an antenna run? What are you trying to > keep the signal out of?
uhhh-the receiver??? > Inter-cabling within the cabinet needs to be double > shielded to prevent interaction between the TX and RX > portions, but once those signals are merged at the > output of the duplexer they are both on the same > feedline anyway and double shielding is expensive and > unnecessary. > For short antenns runs, RG213 is actually an excellent > choice. Not for a permanent installation. I might run it for a test antenna at home, but that's it. > The only exception to this is if there is no duplexer > being used and the repeater is operating on split > antennas with parallel feedline runs, then 100% > shielding is necessary. Under these circumstances > LDM400 or 9913 would be a good choice if heliax is not > available affordably since the cables are not being > used in a duplex setting. > > Dan N8DJP I would still say not for any length. 100' of 9913 has about 1.5 dB loss on 2M, which is getting close to the high end of tolerance for that length. At UHF, it's more like 3dB, and if you're only 100', the height won't be enough to compensate for the loss, unless you're on a buiding top, and even then, going to hardline will be a NOTICABLE improvement. My UHF rptr (on a rooftop) has abt an 80-90' run. I went from 1/2" to 7/8"-just that difference was astounding. -- Jim -------- "The higher you are, the harder it is to pump." -Cleveland Mayor Jane Cambell, after the big black-out of 2003 Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
