Jeff, Maybe you should re-post this every week. Seems like the question comes up about that often. ;-)
Chuck WB2EDV ----- Original Message ----- From: "Jeff DePolo" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, June 07, 2007 11:41 AM Subject: RE: [Repeater-Builder] Which coax cables to use with repeaters? > > I think this is, or should be, a repeater-builder FAQ. > > Foil+braid cables like 9913, LMR-series, etc. should generally NOT be used > in duplex environments. Although a few may report results to the > contrary, > braid-over-foil cables produce noise due to the dissimilar metal contact, > particularly as the cable ages/weathers. As such, they should be avoided. > > Double-silver-shield cables such as RG-142B/U or RG-400/U are RG58-sized > cables good for short runs at UHF and below. Their use at 900 or above > should be kept to very short lengths and/or power levels under 100 watts > due > to the losses involved. RG-393 is slightly smaller in diameter than RG8 > and > is constructed using dual silver braids like RG-142B/U and RG-400/U, so it > is good choice for longer runs and/or higher power levels. RG214/U is > also > a good choice except at very high power levels as, unlike the others cited > above, it has a solid polyethylene dielectric instead of teflon. RG-223 > is > a smaller version of RG-214, again with a double silver braid and poly > dielectric. Be careful when ordering RG-214's. There are "commercial" > grades of RG-214, as compared to mil-C17 types, which have bare copper > braids instead of silver plated. Bare copper braids, even if > double-shielded, should be avoided for the same noise-generating reasons > as > in the case with foil+braid cables. > > Solid-shield cable such as Superflex-type Heliax (FSJ1-50A 1/4", FSJ2-50A > 3/8", FSJ4-50B 1/2") is the best in terms of both loss-versus-size, lack > of > duplex noise, and shielding properties. > > Hope this helps. > > --- Jeff > >> -----Original Message----- >> From: [email protected] >> [mailto:[EMAIL PROTECTED] On Behalf Of Howard Z. >> Sent: Wednesday, June 06, 2007 5:13 PM >> To: [email protected] >> Subject: [Repeater-Builder] Which coax cables to use with repeaters? >> >> I have read that one should use dual-shielded cables. >> >> Which cables are these? >> >> Is Belden 9913F7 a good choice? >> >> Here is its description: http://www.therfc.com/9913f.htm >> >>
