Announcement

Collapse
No announcement yet.

Quad Shield or Dual Shield RG6

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #16
    Originally posted by hbiss View Post
    So if they reused some of the existing cable what does that say about using quad or even dual?

    -Hal
    They, or he obviously doesn't care.
    Rob

    Moderator

    All responses based on the 2017 NEC unless otherwise noted

    Comment


      #17
      Originally posted by LarryFine View Post
      I do not understand any advantage to quad shielding except for manufacturer profit.
      In really high-RF environments it might make a difference, but most people don't live under half a mile from a TV (or clear-channel AM) transmitter.

      Comment


        #18
        Originally posted by LarryFine View Post
        I do not understand any advantage to quad shielding except for manufacturer profit.
        I'm no expert, but read a lot. AIUI, quad is far better on prevention of signals getting out of the coax and is used by the cable co to minimize leakage and interference.

        It's larger, less flexible, more expensive, and often has more loss; look at Belden or Commscope literature. Loss is usually unimportant in the cable distribution (they have amplifiers and equal amplitude for "all" channels), more so for OTA. Also as stated, solid copper is probably better for the feed from power supply to amplifier with longer distances and OTA.

        To emphasize what has been hinted by others ... MATCH CONNECTORS TO CABLE, THEY ARE NOT INTERCHANGEABLE.

        Comment


          #19
          Originally posted by Little Bill View Post
          I added on to my house a couple of years ago. I had to extend a run for my satellite to the new bedroom. I did all the work, including putting the connectors on. The picture was perfect. Later on, I upgraded the Sat. service and the techs had to come in to install the new equipment. When they came to my connectors, they promptly took out their cutters and cut my connectors off and put on theirs!
          The barely trained service techs are the absolute worst. I got an AT&T tech fired after I documented how bad a job he'd done at my parents house a few years ago.

          He tagged the demarc unit to the basement wall with a single screw (the demarc unit is supposed to go on the EXTERIOR of the building), draped coax and CAT5 ACROSS the front of the breaker panel, and ripped apart two punched down cables on a CAT5 patch panel to run a phone line that he was asked not to run.

          AT&T reimbursed my parents for six months of service and fired the tech after I made a stink their behalf. The district manager actually came out to see how bad of a job the guy had done.

          When I had cable service hooked up at my house, I told the tech to land his coax on the grounding block, and leave. He told me he had to inspect the wiring. I said no. I'd done all the wiring inside the house, and he didn't need to worry about it. I finally relented and told him he could hook up his signal strength tester where the cable modem was connected - he told me he'd never seen such strong consistent signal strength before I used dual shield RG6 and Home Depot -quality compression connectors. Weird how not rushing usually makes things better...


          SceneryDriver

          Comment


            #20
            he told me he'd never seen such strong consistent signal strength before I used dual shield RG6 and Home Depot -quality compression connectors.
            I'm sure your work and Home Depot connectors was the reason for that.

            -Hal

            Comment


              #21
              Originally posted by hbiss View Post
              I'm sure your work and Home Depot connectors was the reason for that.

              -Hal
              Just goes to show that craftsmanship tops brand name in many cases.


              SceneryDriver

              Comment


                #22
                What I'm trying to say is when someone pats you on the back consider the source before you take it as a job well done.

                -Hal

                Comment


                  #23
                  Are you using this cable for incoming service? I'm doing my house now I ran dual shield all over but I'm not sure what to run from my data closet to where the incoming service will be I'm thinking just running a cat6 and a coax to cover myself

                  Sent from my SM-G965U using Tapatalk

                  Comment


                    #24
                    Originally posted by nickelec View Post
                    . . . I'm not sure what to run from my data closet to where the incoming service will be I'm thinking just running a cat6 and a coax to cover myself
                    That should do it. If it will be impossible to make any new home runs in the future, run two of each . . . or a conduit.
                    Master Electrician
                    Electrical Contractor
                    Richmond, VA

                    Comment


                      #25
                      Originally posted by nickelec View Post
                      Are you using this cable for incoming service? I'm doing my house now I ran dual shield all over but I'm not sure what to run from my data closet to where the incoming service will be I'm thinking just running a cat6 and a coax to cover myself
                      There are many ways to configure the system so the pre-wiring can be tricky. In my situation tech just used the old cables to get the system up and running, now I need to run a few cables to the actual location where the equipment needs to be. For now I'll be running 3-RG6 cables from the splitter adjacent to the ONT to three new locations. One for the router, a second for an extender, and a third for the Fios One wireless TV/DVR system.

                      I may end up running additional RG6 cables to each TV location but with their new system this isn't necessary unless the wireless signal to the cable boxes ends up being too poor. I'll also need a Cat6 Ethernet cable from the ONT to the router for the WiFi.

                      For a new install I would run a raceway to each location as Larry suggested to future-proof the house.
                      Rob

                      Moderator

                      All responses based on the 2017 NEC unless otherwise noted

                      Comment


                        #26
                        I ran two one inch fmc from data closet area to the room where the service will be coming in from

                        Sent from my SM-G965U using Tapatalk

                        Comment


                          #27
                          I wanted to run it outside but I don't know what service provider I'll be using yet or the wire there going to be bringing in

                          Sent from my SM-G965U using Tapatalk

                          Comment


                            #28
                            The biggest thing with coax is using RG6 vs. RG95. The former has much higher bandwidth so even CATV is far cleaner. Coax has an upper limit on bandwidth that depends on design and also a characteristic impedance mostly 50 ohms. But since a lot of OTA stuff was originally designed for twin lead that is 75 ohms you see that on older setups. If the impedance does not match in the cable, connector, receiver, etc., you get a reflection which is signal loss. This matters far more than cable length or shielding.

                            The signal is high frequency so it actually runs along the surface due to something called the skin effect. If you have a signal on the center conductor and a foil shield you get an image signal on the shield. If it is braided which it often is for mechanical reasons it depends on the hole sizes. All dish antennas except the solid aluminum small ones have a porous mesh inside a fiberglass skin to make them light as well. If the hole size is less than 1/10th of the wavelength it is electrically opaque. Whether there are holes or not or even imperfections does not matter. This goes in both directions. A signal on the outside rides on the outside even in very thin foil and vice versa. The shielding from outside interference is called the Faraday effect or Faraday cage.

                            At DC or low frequency 50/60 Hz AC it rides in the cable. This is where extra thickness can help from a resistance point of view at long lengths if you can’t push enough power to the LNA/LNB. Important in SATV but useless in CATV at least at the residential end,

                            If you add additional shields at RF they do nothing at all.

                            Switching gears high voltage cable needs it. Above 2000 V power cables are shielded but for different reasons. At this point the goal is to make the flux on the insulation as even as possible. Unshielded cables tend to burn up if for instance the cable is accidentally laying against another cable or a grounded surface. A single shield does the trick and works just like coax up to 40 kV. Above that point they have to run 2 shields for 69 kV then more for 115 kV and so on. But obviously communication cables are nowhere near this.

                            CAT6 is an orphan that has gotten popular. CAT5E has a 100 MHz bandwidth. CAT6 has a 200 MHz bandwidth. Ethernet up to 1 gigabit is designed to work in 33 MHz bandwidth. It works just as good on 5E as 6. More bandwidth does nothing. The next standard up is 10 gigabit. Here we have a problem in that twisted pair won’t fix and the venerable RJ45 business line phone connector with its 250 MHz bandwidth is finally finished. We can go about 20-30 feet on CAT5E still just ignoring the losses but we are basically at the limits finally. CAT6 doesn’t increase the distance or anything at all. So we go to CAT7 which has very tiny coaxial cables and a couple competing connectors with extra pins in the corners of the RJ45 connector.

                            CAT6 is billed as future proofing. About the only advantage is it is more rounded so pulls are easier. The only thing it is future proofing since as I said the standards for communication skipped it is that it helps future proof Belden and Commscope margins.

                            If their cable quality is so awful that it needs 4 shields to do the work of 1 you may want to seriously consider a new vendor. There is a slight case for the mechanical strength of braided shielding and blocking microwave and cosmic ray signals in high RF environments on towers with lots of renters. But for home use? Don’t make me laugh. Single shield is fine. Just stop slamming the cable in the doorway you ran it through and stop using push on Chinese F connectors from Walmart and you’d be amazed. Or do what I did...I have many more channels, better quality, more UHD 4K etc. since I ditched cable and satellite and went pure Internet based distribution.

                            With using DSL or Cablemodrm as long as the SNR is high enough it doesn’t matter how high it is...it’s digital. The biggest problem is that with DSL the phone line was never intended to carry anything more than 4 KHz. Like 10 gigabit Ethernet what matters most is distance to the DSLAM (phone company’s transmitter). With cable companies bandwidth isn’t the issue but they are notorious for buying the cheapest cable available. Typically it only has an outdoor rating of 10 years before it should be replaced. Phone company cable was designed on a 50-100 year expected life. As cheap as they are I have no idea how cable companies stay in business. And that line is your problem. No matter how good your coax is, it isn’t rotting in the ground.


                            Sent from my iPhone using Tapatalk

                            Comment


                              #29
                              Originally posted by paulengr View Post
                              The biggest thing with coax is using RG6 vs. RG95. The former has much higher bandwidth so even CATV is far cleaner. Coax has an upper limit on bandwidth that depends on design and also a characteristic impedance mostly 50 ohms. But since a lot of OTA stuff was originally designed for twin lead that is 75 ohms you see that on older setups. If the impedance does not match in the cable, connector, receiver, etc., you get a reflection which is signal loss. This matters far more than cable length or shielding.
                              I'm sure you mean RG-59 which hasn't been used for CATV for at least a couple of decades. Back with 24 channel systems, with an upper frequency of maybe 250Mhz, it was the cable of choice. But today, with the upper frequency exceeding 1Ghz the loss is too much to be of any use.

                              Note also that actual RG cables date back to WWII with RG meaning Radio Grade. (There may be some controversy over what RG meant.) Original RG cable is still being made today with the RG designation printed on the jacket, however it doesn't find any use in CATV or even OTA because it's design is still the original single copper braid over a solid polyethylene dielectric and a solid copper center conductor. Because of the solid poly dielectric the loss is quite high. RG cables find there uses in baseband video. About the only place today would be CCTV camera systems.

                              The designers of the cables we use today kept the old familiar original size designations (RG-59, RG-6, RG-11, etc). We call a cable that is roughly the size of the old RG-6, RG-6 but that's really just slang for a cable that bears little resemblance construction wise and performance wise to the the original.

                              Coax cables can be had in many characteristic impedances. The cables we use for CATV and TV have always been 75 ohms. Back in the early days of TV 300 ohm twin-lead was popular because of it's ease of use, low loss and low cost. But that was replaced with RG-59 when the number of homes with multiple TV grew because it could be run within walls and around a house which you couldn't do with twin-lead.

                              Up until maybe 20 years ago you would still see TVs with 300 ohm screw terminals for the antenna input. We always kept a supply of 300-75 ohm matching transformers because they always were needed. I think I still have some someplace.

                              -Hal
                              Last edited by hbiss; 08-04-19, 01:24 PM.

                              Comment

                              Working...
                              X