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  • Originally posted by North Borneo Radar View Post
    Hi, best to contact FR24 at this email address : support@FR24.com regarding your issue.
    Cheers, sent them an email, hope they have a solution
    http://belconnenweather.net
    http://scanact.net
    FR24 alias - F-YSCB1

    Comment


    • For anyone who's still interested, the long lost T-YBBN1 at Brisbane has reappeared and seems to be providing the same coverage as before. Welcome back and also thanks to all the other feeders who have sprung up around Brissy while it has been absent - please don't go away any of you.

      Comment


      • Originally posted by airnrail View Post
        For anyone who's still interested, the long lost T-YBBN1 at Brisbane has reappeared and seems to be providing the same coverage as before. Welcome back and also thanks to all the other feeders who have sprung up around Brissy while it has been absent - please don't go away any of you.
        Fantastic. When I saw T-YBBN1 today I thought maybe the feeder was back and you are correct. Do we have any idea where the feeder is located, as the coverage is excellent.
        Regards

        Comment


        • Originally posted by vk2tv View Post
          Hi All,

          The subject of cable loss is often discussed and often misunderstood, even by people who should know better. Yes, cable loss CAN be important but it needs to be taken into perspective, the loss figures in isolation being somewhat less important than they might seem to be.


          Ray
          vk2tv
          Now
          officially T-YPMQ1
          Hi Ray,
          Yes, the wonderful science of coax cable. You mention high towers and I had often wondered about cable loss you raise about such long runs down....or is it up? these towers.

          I had some RG60, quad I had left over from a Cable TV installation I had to use on a new house build. Used it for my Air-band scanner connected to my Discone. Run is about 50 metres, and seems to work great. I happen to also have about 10 metres of RG213 8.6dB Beldon...real stuff. But thought adding this into the total run (say from the antenna into the roof cavity along the feed and connected to my RG60 will not assist with "better" coverage.

          Regards

          Comment


          • Originally posted by POR911 View Post
            Hi Ray,
            Yes, the wonderful science of coax cable. You mention high towers and I had often wondered about cable loss you raise about such long runs down....or is it up? these towers.

            I had some RG60, quad I had left over from a Cable TV installation I had to use on a new house build. Used it for my Air-band scanner connected to my Discone. Run is about 50 metres, and seems to work great. I happen to also have about 10 metres of RG213 8.6dB Beldon...real stuff. But thought adding this into the total run (say from the antenna into the roof cavity along the feed and connected to my RG60 will not assist with "better" coverage.

            Regards
            Por911, Hi

            I did some reverse engineering on that installation on the 1000' tower and it looks like they used something akin to Andrews LDF5-50, 7/8" diameter Heliax with a loss of about 0.93dB/100'. For high-power broadcasting installations (FM & TV) 5" diameter Heliax is not uncommon, with a loss of 0.31dB/100' at 960MHz. Yep, coax can be interesting. You might find this interesting, if you ignore the mathematics .... http://en.wikipedia.org/wiki/Coaxial_cable

            I wouldn't hesitate to use 75 ohm coax on a 50 ohm antenna (or 50 ohm cable on a 75 ohm antenna), which is what you're doing. I'd be less willing to extend 75 ohm cable with 50 ohm cable because, depending on the lengths of both the 75 ohm and 50 ohm cable, and depending on the characteristics of the antenna (i.e. how close is is to being 50 ohms), you could end up with an undesirable mismatch to your receiver. As for feeding a 50 ohm antenna with 75 ohm cable the mismatch is negligible at 1.5:1 VSWR. A bog standard Ground Plane has a feed impedance of 37.5 ohms but these days 50 ohm cable is always used, the resulting mismatch being 50/37.5 or about 1.5:1. In the early(ish) days of two-way radios Pye Industries used 35 ohm coaxial cable in early mobile installations, but it hasn't existed for many, many years, there being no real need to not use readily available 50 ohm cable. In broadcasting, however, where reflections resulting from a mismatched cable/antenna can cause technical issues (ghosting, e.g. with analog TV) every effort is made to achieve a perfect match. It's horses for courses.

            Ray
            vk2tv

            Comment


            • Originally posted by vk2tv View Post
              Por911, Hi

              I did some reverse engineering on that installation on the 1000' tower and it looks like they used something akin to Andrews LDF5-50, 7/8" diameter Heliax with a loss of about 0.93dB/100'. For high-power broadcasting installations (FM & TV) 5" diameter Heliax is not uncommon, with a loss of 0.31dB/100' at 960MHz. Yep, coax can be interesting. You might find this interesting, if you ignore the mathematics .... http://en.wikipedia.org/wiki/Coaxial_cable



              I wouldn't hesitate to use 75 ohm coax on a 50 ohm antenna (or 50 ohm cable on a 75 ohm antenna), which is what you're doing. I'd be less willing to extend 75 ohm cable with 50 ohm cable because, depending on the lengths of both the 75 ohm and 50 ohm cable, and depending on the characteristics of the antenna (i.e. how close is is to being 50 ohms), you could end up with an undesirable mismatch to your receiver. As for feeding a 50 ohm antenna with 75 ohm cable the mismatch is negligible at 1.5:1 VSWR. A bog standard Ground Plane has a feed impedance of 37.5 ohms but these days 50 ohm cable is always used, the resulting mismatch being 50/37.5 or about 1.5:1. In the early(ish) days of two-way radios Pye Industries used 35 ohm coaxial cable in early mobile installations, but it hasn't existed for many, many years, there being no real need to not use readily available 50 ohm cable. In broadcasting, however, where reflections resulting from a mismatched cable/antenna can cause technical issues (ghosting, e.g. with analog TV) every effort is made to achieve a perfect match. It's horses for courses.

              Ray
              vk2tv
              Hi Ray,
              Thanks for the comments. I can imagine it is quite a science getting the correct cable to fitting to device match. I find the 75ohm RG60 worked very well for the scanner, though, I am close to YBBN airport, and the discone does a reasonable job. It amazed me how a simple rabbit ears setup in the cavity of my roof ceiling was not far away from the reception my discone gives me. When I had a survey carried out, the radio tech said that because of my proximity to the tower, and the way air-bands 'bend', any antenna would do the trick..He was correct.

              Regards

              Geoff

              Comment


              • Originally posted by POR911 View Post
                Hi Ray,
                Thanks for the comments. I can imagine it is quite a science getting the correct cable to fitting to device match. I find the 75ohm RG60 worked very well for the scanner, though, I am close to YBBN airport, and the discone does a reasonable job. It amazed me how a simple rabbit ears setup in the cavity of my roof ceiling was not far away from the reception my discone gives me. When I had a survey carried out, the radio tech said that because of my proximity to the tower, and the way air-bands 'bend', any antenna would do the trick..He was correct.

                Regards

                Geoff
                Hi Geoff,

                Antennas and feedlines have lots of theory behind them and some people rely heavily on that theory and treat the theory books like bibles. That really is the correct approach, however, there are many more people working in the industry with so many years of practical application that they rarely need to look at a book to find out what to do. One learns intuitively what works, might work or won't work. For transmitting applications there is a need to achieve a respectable match between components - transmitter to cable, cable to antenna. In receiving applications the same theory applies as it does for transmitters, however, there is a lot more latitude for error, and I have long believed that where a job can't be installed in accordance with "best practice", use the SIAS (suck it and see) principle. Aim for the best that you can achieve in your circumstances.

                Cheers,
                Ray

                VHF (such as Air Band) and UHF (adsb is a close fit here) waves were always thought to travel in a straight line and provided the receiver could see the transmitter a circuit could be established. In practice those radio waves do "bend" in that they tend to follow the curvature of the earth. Just how much they bend depends on prevailing climatic conditions. As a rule of thumb the earth is assumed to be four-thirds its real diameter so, to the radio wave it appears flatter than it really is, thus extending the horizon a bit.

                Comment


                • Originally posted by vk2tv View Post
                  VHF (such as Air Band) and UHF (adsb is a close fit here) waves were always thought to travel in a straight line and provided the receiver could see the transmitter a circuit could be established. In practice those radio waves do "bend" in that they tend to follow the curvature of the earth. Just how much they bend depends on prevailing climatic conditions. As a rule of thumb the earth is assumed to be four-thirds its real diameter so, to the radio wave it appears flatter than it really is, thus extending the horizon a bit.
                  Hi Ray

                  I can recall many years ago doing my PPL that VHF was line of sight, but as you say, depending on weather conditions coverage can increase/decrease. I have been trying to listen to 'center' controllers conversations. Maybe a combination of insufficient antenna height, antenna tuning, and distance.

                  Regards

                  Geoff

                  Comment


                  • Originally posted by POR911 View Post
                    Hi Ray

                    I can recall many years ago doing my PPL that VHF was line of sight, but as you say, depending on weather conditions coverage can increase/decrease. I have been trying to listen to 'center' controllers conversations. Maybe a combination of insufficient antenna height, antenna tuning, and distance.

                    Regards

                    Geoff
                    Geoff,

                    The line of sight rule of thumb still remains valid. Be pleasantly surprised when prevailing conditions extend your range beyond LOS and be a bit disappointed on those days with 10% humidity where it may not quite reach LOS. Mother Nature likes to play games with us<grin>.

                    There is no substitute for antenna height above ground because it extends your visual (and radio) horizon. Radio signals diminish in a square function with distance - double the distance, quadruple the path loss. Objects along a path can also contribute additional loss. Things such as trees and buildings all make a contribution, which is why higher is better for antenna placement. For an obstructed path, moving the antenna sideways can sometimes bring about an improvement in received signal.

                    Cheers
                    Ray

                    Comment


                    • G'day folks,
                      I've just recently received my FR24 receiver kit and I'll be putting it on the air very shortly. (Once this soon to be cyclone buggers off)
                      I'm located in Innisfail and have pretty good coverage to the north, west and south. (I have a dirty great hill to the east of me)
                      The FR24's antenna will take pride of place on my 13 metre mast so coverage shouldnt be too bad.
                      I do have a question though, has anyone here setup the FR24 receiver on a wireless network?
                      If so, can you give me a few pointers?

                      Many thanks.
                      Jeff VK4XA
                      -
                      Jeff Cochrane - VK4XA
                      East Innisfail, QLD, Australia
                      F-YDKI1

                      Comment


                      • Originally posted by VK4XA View Post
                        G'day folks,
                        I've just recently received my FR24 receiver kit and I'll be putting it on the air very shortly. (Once this soon to be cyclone buggers off)
                        I'm located in Innisfail and have pretty good coverage to the north, west and south. (I have a dirty great hill to the east of me)
                        The FR24's antenna will take pride of place on my 13 metre mast so coverage shouldnt be too bad.
                        I do have a question though, has anyone here setup the FR24 receiver on a wireless network?
                        If so, can you give me a few pointers?

                        Many thanks.
                        Jeff VK4XA
                        Jeff,

                        I am YDKI1 located at Mission Beach just opposite Dunk Island. Been on/off for last 6 months as I do a lot of travelling.
                        I get up to 280 miles range with SBS-3 and SBS supplied whip approx. 12" long with a TV pre-amp, because of the shielding of the mountain next to my home, I get aircraft from 80 miles north of Cairns to approx. 80 to 100 miles south of AYR, with an out to sea range of up to 280 miles. Obviously these aircraft are higher than 38,000 feet generally FL410 etc. Out west I am generally stuck to 50 miles max.

                        I travel a fair bit, hence spasmodic reports from YDKI1, I try to use the same login etc when away alas it seems that the system blocks a report from a station that is too far away from the "registered" home? perhaps some one could advise.

                        Cheers,

                        Traveller

                        Comment


                        • Originally posted by Traveller View Post
                          Jeff,

                          I am YDKI1 located at Mission Beach just opposite Dunk Island. Been on/off for last 6 months as I do a lot of travelling.
                          I get up to 280 miles range with SBS-3 and SBS supplied whip approx. 12" long with a TV pre-amp, because of the shielding of the mountain next to my home, I get aircraft from 80 miles north of Cairns to approx. 80 to 100 miles south of AYR, with an out to sea range of up to 280 miles. Obviously these aircraft are higher than 38,000 feet generally FL410 etc. Out west I am generally stuck to 50 miles max.

                          I travel a fair bit, hence spasmodic reports from YDKI1, I try to use the same login etc when away alas it seems that the system blocks a report from a station that is too far away from the "registered" home? perhaps some one could advise.

                          Cheers,

                          Traveller
                          Can't help you with the radio stuff as I'm not a feeder just a plane nut! I've seen YDKI1 quite a few times. You certainly do get good coverage out to sea and you are the only one that seems to get the traffic from NZ to Japan in those parts. I've wondered if you were at Mission Beach as I couldn't really see the bloke who owns Dunk being a FR24 feeder. Cheers.

                          Comment


                          • Originally posted by airnrail View Post
                            Can't help you with the radio stuff as I'm not a feeder just a plane nut! I've seen YDKI1 quite a few times. You certainly do get good coverage out to sea and you are the only one that seems to get the traffic from NZ to Japan in those parts. I've wondered if you were at Mission Beach as I couldn't really see the bloke who owns Dunk being a FR24 feeder. Cheers.

                            The name Flight radar assigns to you is based upon the nearest registered airport, nothing to do with the actual location. I guess your nearest airport is Innisfail and your the first one there to use FR24 hence your "handle" My nearest registered airport is Dunk Is, otherwise I probably would have been Tully etc.
                            Enjoy!

                            Comment


                            • Originally posted by Traveller View Post

                              I travel a fair bit, hence spasmodic reports from YDKI1, I try to use the same login etc when away alas it seems that the system blocks a report from a station that is too far away from the "registered" home? perhaps some one could advise.

                              Cheers,

                              Traveller
                              Correct. Error reduction in place means if you are more than about 400m from where your home location is flagged traffic is ignored. This prevents erroneous data being used to plot tracks
                              Posts not to be taken as official support representation - Just a helpful uploader who tinkers

                              Comment


                              • Thank you, just goes to show "ask" and knowledge flows forth!

                                Thanks

                                Comment

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