Also, the 'real' RG-214 is seriously more expensive.
Neil Glenn Little WB4UIV wrote: > > RG-214 type cable looks like RG-214 from the outside. However, it is not > true RG-214, hence the use of "type" in the name. > > True RG-214 has a silver plated center conductor as well as two silver > plated shields. > > RG-214 is the newer designation for RG-9. Early RG-9 had one copper and a > silver plated shield. Later versions had two silver shields. > > RG-214 commercial or type cable may or may not have any silver in the > cable. The dielectric constant may be different. > > Silver has pretty much the same conductivity as silver oxide. This is one > of the reasons for using silver in RF. > > Hope that this helps clear up a little about RG-214 type cable. > > 73 > Glenn > WB4UIV > > At 04:00 AM 11/28/04, you wrote: > > >I never understood either why 214 is quoted as 99% shield with it's 2 > >braids. I would think it would be 100% with lots to spare. > > > >The 100% shield designation comes from having both a braid and a tape > >shield. The tape is theorietically the 100% shield and the braid is > >placed over it to act as a strain relief. > > > >The reason it desenses it's self is the dissimilar metal condition the the > >tape presents to the braid. The power from the transmitter creates "Micro > >arcs" in between the shields and bounces around like pac-man. You can use > >it for the cables to and from the duplexer, but running power down the > >wire creates the arcs so you get a general rise in the noise floor when > >trying to recieve back through it. Using this type of cable for the > >antenna run is a sure way to get kicked off a mountain top. > > > >Take a look at standard cable guy issue RG-6. This is a prime example of > >coax not to use. The tape is 100% coverage, Then that is covered with 25% > >- 60% braid depending on how cheap your cable company is. It gets better, > >The center conductor "Stinger" is copper clad steel, this has been a RF > >nightmare from the get go as tempreture changes. Try doing a google search > >to find the different tempreture expansion and contraction rates of > >materials and compare them. Over several years the steal to copper bond > >breaks with tempreture and user movement and the microfractures will > >create noise in the coax, especially when moved. > > > >But it is cheap so who cares? The only saving factor is that both the > >braid and tape are aluminum, you can't solder a connector to it to save > >your life, but you can crimp all day long. Then you have the problem of > >the sucked fitting which will attenuate signal below 100MHz but pass > >everything else fine. And there are impedence bumps if the coax wasn't > >rolled right. > > > > > >To answer another question, the braid of the Flexi took the solder, the > >tape shield did not. I held the connector upright and dumped an ass load > >of solder down the holes so it got the threads of the connector all nice > >and goopy. And yes, I will admit to buying the $5.20 each silver plated > >teflon connectors from the local Radio shack. But when you are down and > >out on a holiday week-end, you have to make "Sacrifices". > > > >"Scott" <[EMAIL PROTECTED]> wrote: > > > > >Thanks All----Sounds like I'd better go with some sort of hard line for > > my between unit RF interconnects to keep between cable leakage to > > tolerable limits----and probably noise too. But this brings up another > > issue: forgetting about noise for the moment ---how can a 214 type cable > > which is listed as 97-98% shielded have lower leakage (desense problems) > > than a foil cable listed as 100% shielded? > > > > > >The big question-------what is the most economical combination of small > > diameter hard line and an "N" compatible connector assembly?--------is > > there something that can be done with say 1/4" superflex and the > > affordable solder through the holes teflon "N" connector that is similar > > to the 259 "UHF" connector?----what is the best way to go? > > > > > >And another-------I've seen military microwave gear interconnected with > > hardline less than 1/4" diameter ---smooth tubing---with soldered on "N" > > connectors-----like is used in mobile helical duplexers-----is this > > system suitable and where does it come from? > > > > > >Thanks much, 73 > > >Scott, N6NXI > > > ----- Original Message ----- > > > From: Scott Overstreet > > > To: [email protected] > > > Cc: Scott Overstreet > > > Sent: Saturday, November 27, 2004 5:44 PM > > > Subject: [Repeater-Builder] Coax Question > > > > > > > > > OK guys ---I hear you all saying that hard line is better but none of > > you have said what is the actual problem with 9913 flex or LMR-400. In > > other words---What is wrong with a quality foil under braid > > "100%"shielded foam cable and I'm assuming use between receiver > > and duplexer, transmitter and duplexer and duplexer and antenna? > > > > > > And then the next question that follows is that inside a cabinet full > > of stuff where 1/2 inch hard line is just to stiff -----what do you > > suggest ---and in this case assume that we are talking about three or > > four repeaters----yes, receivers, transmitters, isolators and duplexers > > all in the same rack cabinet? > > > > > > Scott > > > N6NXI > > > > > > > > > > > > Yahoo! Groups Links > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
