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 <*> 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/
