Re: [Repeater-Builder] Re: Which coax cables to use with repeaters?
At 6/7/2007 15:13, you wrote: --- In Repeater-Builder@yahoogroups.com, Tedd Doda [EMAIL PROTECTED] wrote: Bob: Just curious about the double braided cables like 214. Wouldn't they also suffer from the same situation where the 2 braids rub on each other? No, the key is the SILVER, which conducts extremely well whether it is oxidized or not. Aluminum and copper do not exhibit this characteristic. Plus, a lot is said about dissimilar metals here, but same-metal braids, if not silver plated, create the same problems very often. RG213 should be avoided for this reason, and, the non-silver plated braids of some RG214, for example. Ditto here; have found the exact same results via real-world experience. Bob NO6B
Re: [Repeater-Builder] Re: Which coax cables to use with repeaters?
Other than Heliax hardline, RG-214 is undoubtedly the best choice for cable, but having said that, while Wacom used RG-142 on their uhf duplexer, they used cable labeled: Modified RG-214 DOUBLE SHIELDED which did not have silver plating on the shields. I talked with Lloyd Alcorn at Wacom regarding this some 25 years ago and he felt that for interior use for duplexer connections, double shielded copper conductors with a low migration outer cover would not oxidize sufficiently to produce any noise. I recently opened up one of their VHF duplexer interconnect cables and it looked like it was made up that day. Has anyone aboard experienced any problems with their cables? In a message dated 6/15/2007 9:44:45 A.M. Pacific Daylight Time, [EMAIL PROTECTED] writes: Plus, a lot is said about dissimilar metals here, but same-metal braids, if not silver plated, create the same problems very often. RG213 should be avoided for this reason, and, the non-silver plated braids of some RG214, for example. ** See what's free at http://www.aol.com.
[Repeater-Builder] Re: Which coax cables to use with repeaters?
Depends really 9913 is a good cable to use if you run modest lengths, the cable doesn't have to move a lot and you don't run really high power. Here's the dope... The coax is most often a very cost effective choice. The loss for modest length runs is not bad. You should pay serious attention to the coax material and mechanical construction issues for your specific application. The center conductor is often mounted in foam or a hybrid air foam type layout, which has a potential to become problematic. It is possible the center conductor can migrate out of alignment with sharp radius bends and heated center dilectric problems. Because of these two issues I'm not much of a fan about using any foam center coax. There's also a crush problem I'm not going to address in this post... But I have friends who run 9913 with great results. My coax choice before 9913 would be RG-214 mil spec. Stay away from LMR dissimilar metal type coax cables in/for duplex (repeater) operation... cheers, skipp Howard Z. [EMAIL PROTECTED] wrote: 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
[Repeater-Builder] Re: Which coax cables to use with repeaters?
Hi Jeff, Jeff DePolo [EMAIL PROTECTED] wrote: 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. What really fans the LMR-400 is ok fire... is the number of Wifi people using it. They don't normally report the duplex operation problems because the wifi stuff is normally a half duplex operation. 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. Is 9913 a dissmilar metal coax? I've seen some versions with a thin copper foil... but not aluminum. cheers, skipp
Re: [Repeater-Builder] Re: Which coax cables to use with repeaters?
skipp025 wrote: Depends really 9913 is a good cable to use if you run modest lengths, the cable doesn't have to move a lot and you don't run really high power. Here's the dope... The coax is most often a very cost effective choice. The loss for modest length runs is not bad. You should pay serious attention to the coax material and mechanical construction issues for your specific application. The center conductor is often mounted in foam or a hybrid air foam type layout, which has a potential to become problematic. It is possible the center conductor can migrate out of alignment with sharp radius bends and heated center dilectric problems. Because of these two issues I'm not much of a fan about using any foam center coax. There's also a crush problem I'm not going to address in this post... But I have friends who run 9913 with great results. My coax choice before 9913 would be RG-214 mil spec. Stay away from LMR dissimilar metal type coax cables in/for duplex (repeater) operation... cheers, skipp Both 9913 and 9913F use dissimilar metal shield materials. They both use DuoFoil aluminum foil / polyester tape under tinned copper. You may get lucky, but most folks end up with problems. Unless you feel very lucky, 9913 and the LMR series of coaxes should be avoided in duplex applications. Ed Yoho WA6RQD
Re: [Repeater-Builder] Re: Which coax cables to use with repeaters?
LMR cables, or any with braid-over-foil, will expand and contract if used outdoors (or in other non-controlled environments), which tends to occur in repeater situations. After a while, this slight mechanical shifting will cause problems, including noise, as the braid rubs over the foil. Dis-similar metals then act as rectifiers (point-contact) as corrosion creeps in. Same thing can happen if the coax is allowed to flex in the wind. Sharp bending, or repeated bending, will also break the foil and/or mylar wrapping (i.e. inner shield), thus reducing the effectiveness of the foil. The mylar will stretch a little bit, the foil usually fractures. I had two LMR400 jumper cables that have become totally useless due to repeated bending in a 2ft radius arc. I'm pretty sure that this topic has been covered in a couple of articles on www.repeater-builder.com, but perhaps it needs some more definitive statements. Bob M. == --- skipp025 [EMAIL PROTECTED] wrote: Depends really 9913 is a good cable to use if you run modest lengths, the cable doesn't have to move a lot and you don't run really high power. Here's the dope... The coax is most often a very cost effective choice. The loss for modest length runs is not bad. You should pay serious attention to the coax material and mechanical construction issues for your specific application. The center conductor is often mounted in foam or a hybrid air foam type layout, which has a potential to become problematic. It is possible the center conductor can migrate out of alignment with sharp radius bends and heated center dilectric problems. Because of these two issues I'm not much of a fan about using any foam center coax. There's also a crush problem I'm not going to address in this post... But I have friends who run 9913 with great results. My coax choice before 9913 would be RG-214 mil spec. Stay away from LMR dissimilar metal type coax cables in/for duplex (repeater) operation... cheers, skipp Howard Z. [EMAIL PROTECTED] wrote: 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 Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out. http://answers.yahoo.com/dir/?link=listsid=396545469
[Repeater-Builder] Re: Which coax cables to use with repeaters?
--- In Repeater-Builder@yahoogroups.com, Tedd Doda [EMAIL PROTECTED] wrote: Bob: Just curious about the double braided cables like 214. Wouldn't they also suffer from the same situation where the 2 braids rub on each other? No, the key is the SILVER, which conducts extremely well whether it is oxidized or not. Aluminum and copper do not exhibit this characteristic. Plus, a lot is said about dissimilar metals here, but same-metal braids, if not silver plated, create the same problems very often. RG213 should be avoided for this reason, and, the non-silver plated braids of some RG214, for example. Laryn K8TVZ
RE: [Repeater-Builder] Re: Which coax cables to use with repeaters?
Good ol' 9913 uses the same Belden DuoBond II shield like they use in RG6-type cables. It is aluminum foil/mylar with a relatively loose (90% coverage) tinned copper braid over it. LMR-type cable uses the same shield construction as 9913. The primary difference between 9913 and LMR-series cables is the dielectric. 9913 uses the semi hollow dielectric comprised of a tube of solid dielectric with a spiral spacer between it and the center conductor. This reduces the loss (and increases the Vf) as compared to having a solid dielectric. LMR, on the other hand, uses a low-density foam dielectric, no spacer or air. It's easy for 9913 to turn into a water hose. I've had this happen at more than one site; scratch your head and wonder how the top of the cabinet is dry but the floor inside the cabinet is wet... --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of skipp025 Sent: Thursday, June 07, 2007 3:13 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Which coax cables to use with repeaters? Hi Jeff, Jeff DePolo [EMAIL PROTECTED] wrote: 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. What really fans the LMR-400 is ok fire... is the number of Wifi people using it. They don't normally report the duplex operation problems because the wifi stuff is normally a half duplex operation. 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. Is 9913 a dissmilar metal coax? I've seen some versions with a thin copper foil... but not aluminum. cheers, skipp Yahoo! Groups Links No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.472 / Virus Database: 269.8.11/837 - Release Date: 6/6/2007 2:03 PM
Re: [Repeater-Builder] Re: Which coax cables to use with repeaters?
Someone kindly answered before I had a chance. In addition, both braids in mil-spec 214 are made of the same material and will expand and contract in unison, unlike the foil and braid in LMR. So the problem is much less severe, if it even happens at all. Bob M. == --- Tedd Doda [EMAIL PROTECTED] wrote: On Thu, 7 Jun 2007 14:15:04 -0700 (PDT), Bob M. wrote: After a while, this slight mechanical shifting will cause problems, including noise, as the braid rubs over the foil. Bob: Just curious about the double braided cables like 214. Wouldn't they also suffer from the same situation where the 2 braids rub on each other? Tedd Doda, VE3TJD Lazer Audio and Electronics Baden, Ontario, Canada www.ve3tjd.com (personal) www.eraradio.ca (Linked repeater system) We won't tell. Get more on shows you hate to love (and love to hate): Yahoo! TV's Guilty Pleasures list. http://tv.yahoo.com/collections/265
[Repeater-Builder] Re: Which coax cables to use with repeaters?
What about LDF4-50A coax cable? Is it a better choice than FSJ4-50B? Howard --- In Repeater-Builder@yahoogroups.com, Jeff DePolo [EMAIL PROTECTED] wrote: 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: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Howard Z. Sent: Wednesday, June 06, 2007 5:13 PM To: Repeater-Builder@yahoogroups.com 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 Yahoo! Groups Links No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.472 / Virus Database: 269.8.11/837 - Release Date: 6/6/2007 2:03 PM
[Repeater-Builder] Re: Which coax cables to use with repeaters?
Ok Andrew FSJ4-50B 1/2 coax cable - best choice - CHECK! Thanks for the help Howard --- In Repeater-Builder@yahoogroups.com, Jeff DePolo [EMAIL PROTECTED] wrote: 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: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Howard Z. Sent: Wednesday, June 06, 2007 5:13 PM To: Repeater-Builder@yahoogroups.com 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 Yahoo! Groups Links No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.472 / Virus Database: 269.8.11/837 - Release Date: 6/6/2007 2:03 PM
Re: [Repeater-Builder] Re: Which coax cables to use with repeaters?
Howard Z. wrote: What about LDF4-50A coax cable? Is it a better choice than FSJ4-50B? Howard The FSJ4-50B (1/2 Superflex) is much more flexible and can support tighter radius bends. For in cabinet jumpers it is hard to beat. In most cases, the smaller FSJ1-50 (1/4) or FSJ2-50 (3/8) will be much easier to work with. The LDF4-50A is standard 1/2 hardline and would normally be used to get from the duplexer to the antenna. Ed Yoho WA6RQD
