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RPI Zero W not feeding with big antenna but feeding with small antenna

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  • RPI Zero W not feeding with big antenna but feeding with small antenna

    Hi guys,

    Great Forum, thanks for the help so far!

    Briefly introducing myself, aviation enthusiast feeding from close to HSSJ airport. I'm currently 1 of the 2 feeders in this city with more than 1 million people.

    Hopefully someone with a bit of knowledge can help me out here.

    I've got a RPI zero W feeding to FR24 with a black dongle and small antenna. (see pic 1)

    I also purchased an outdoor antenna (see pic 2) which is installed on my roof.

    If I connect my outdoor antenna with a cable connector to my black dongle (see pic 3) it doesn't pick up any aircraft. FR24 says everything is connected and all systems are up and running if I run:

    Or if I check
    Of course you'll say that there is probably a problem with my cable to the antenna or the antenna itself. The strange thing is that when I put the dongle in my laptop and run some other software to listen to FM radio, the dongle and outdoor antenna work fine...

    So I'm quite confused.

    I've also bought a silver dongle (I initially thought it was the dongle which was faulty) (see pic 4) to see if that helps, but the results are exactly the same.

    I've got 3 question to get further.
    - Does anyone have a good tip on how to test my outdoor antenna and dongle on a Windows or Mac laptop to make sure the antenna and cable to the antenna are fine.
    - Are there any known issues with power supply to the dongle with the RPI zero W when connected to a larger antenna?
    - Do I need to install the drivers for the silver dongle according to the website rtl-sdr. com / rtl-sdr-quick-start-guide (sorry I can't post links in my first posts on this forum) or do the standard drivers from the FR24 image work with the silver dongle work out of the box?

    Any help is appreciated!


  • #2
    My guess: RPA-SMA connector.

    Check if the cable you are connection to the silver rtl-sdr v3 receiver has a pin in the center.
    If it doesn't, you'll need an adapter.


    • #3
      I have the adapter you describe. See pic 3rd picture in my first post. I currently have 3 options to connect:
      - Black usb dongle with small antenna (works)
      - Black usb dongle with RPA-SMA connector to my outdoor antenna (doesn't work)
      - RTL-SDR v3 dongle straigth to my outdoor antenna (doesn't work)

      Both dongles give me a good result when running the command
      rtl_test -t
      But when I connect my dongle to my laptop and listen to FM radio, the outdoor antenna works.

      That's why I'm a bit lost.

      Any good ideas to test the outdoor antenna with my laptop?


      • #4
        I just came across an old post saying this:

        USB RPi power Draw
        TV Sticks often need external power booster to USB to keep some sticks 'alive' (USB power down) causing un-explainable errors. Likewise some extension USB cables can do this - an external 2-3Amp power supply is highly recommended before posting of issues.
        Let me try this as well. I'm suspecting that the RPi Zero W doesn't provide enough power to the USB dongles when I connect the outdoor antenna.


        • #5
          You need an adapter to SMA, and adapter to RP-SMA will not work, it's missing the required middle in the SMA connector has.

          Note that you didn't post a photo of the adapters you use with the rtl-sdr stick.

          I suppose the adapter to MCX you posted a photo of should work with the black dongle and the outdoor antenna.
          Not sure why it wouldn't work.

          So you power off, change to small antenna: feeder works
          Power off, change to large antenna: feeder doesn't work with either adapter/dongle?

          Post a picture of how you mounted the antenna.
          Could also be a defective cable i suppose.

          Looks like you bought from jetvision, normally the cabling and adapters should work.
          As i said, a couple of photos of your setup wouldn't hurt.
          Last edited by wiedehopf; 2019-12-11, 19:04.


          • #6
            Sorry for my delayed reply. I needed to climb on the roof to get a picture.

            Pic 1 is my roof antenna mounted on the highest point of my roof.
            Pic 2 shows the white antenna cable coming from the roof and the adapter.

            So if my antenna or cable is broken, how can I easily test that with software on my Mac or Windows laptop?

            Thanks again!


            • #7
              That cabling doesn't look like it's the correct one for 1090 MHz.
              Can you provide a link to where you bought it or a data sheet?
              How long is the cable?

              I'd just recommend buying proper cable, with that diameter it can't be good cable.
              This is proper cable for 1090 MHz:

              I'm not sure where you could source something like this or if you can get it shipped.
              There are other options like using an amplifier:
              But that needs a short cable to connect the amplifier and then the rest of the cable run to the receiver.
              So it's probably more complicated.

              The antenna mounting location looks good.
              How long have you had it up there?
              Maybe i'm mistaken about the cable being the issue, it looks like a jetvision antenna, sometimes the water seal at the base of the antenna goes bad allowing water into the antenna leading to corrosion. If that's the case you would need to open the antenna, clean off any corrosion, maybe redo some solder and seal it back up.

              What model is the antenna?
              Last edited by wiedehopf; 2019-12-15, 11:43.


              • #8
                Wiedehopf, thanks for the replies and help so far! Much appreciated.

                Today, together with the help of someone, I've ruled out the cable being the problem. The conductivity in the cable is good. Also there is no corrosion in the connector at the antenna, checked that as well.

                The antenna and cable are both from Jetvision

                The cable is the 10 meter version.

                The cable goes directly into the silver dongle ( and with the black dongle I connect it with the adapter as shown before.

                So maybe the antenna is the problem. Although I find that very unlikely. I've had the antenna for over a year, but because I never got it to work, I forgot about it for a while.

                The cable on your link is similar to mine, just not as long but with the same connectors.

                So we're going forward with either being the antenna or the USB power being the issue.

                I'm still sourcing a powered USB hub to see if the latter is the problem.

                edit: Looking at the website I see I've probably bought the combination package with antenna, cable and dongle:


                • #9
                  I wouldn't expect the antenna to be bad after only one year.

                  And USB power really doesn't explain why the small antenna would work.

                  The cable isn't the greatest with around 3 dB attenuation, but it should do the job.

                  Well there is the possibility you somehow have strong interference making reception from the big antenna impossible.
                  You should do a spectrum scan:
                  I believe this thread has an option for windows?


                  • #10
                    Small update. I know the other guy in town with a FR24 feed unit. I've taken his unit to my place and connected it to my antenna. Works like a charm...

                    So must be a RPI problem which I can't figure out at the moment. I'll keep trying. I'm guessing USB or driver related.


                    • #11
                      Which filtering does the other guy have?
                      If he's running the FR24 supplied unit, it's much more resistant to non 1090 MHz frequencies.

                      But it's really hard to tell what the problem is.
                      As i wrote above, do a spectrum scan:


                      • #12
                        Yes he has a FR24 supplied unit. I've been reading on it, apparently it has a Mode S Beast unit in it.

                        I have a new Pi on order, but it might take some time before it's in my hands. I'll let you know when I've got it working. Can't find a USB hub anywhere around here.

                        See image for the spectrum scan. What can you make out of it?


                        • #13
                          That image was compressed to much to be usable. See attached pics.
                          Attached Files


                          • #14
                            The spectrum around 1090 MHz looks all wrong, there shouldn't be anything strong around that frequency.
                            The bands seen there in your spectrum are most likely harmonics from a strong transmitter on some other frequency.

                            The best thing you can get for filtering:
                            (be sure you get the FILTERED version, there is an unfiltered version as well on the products page)

                            You can just connect it to the silver rtl-sdr v3 dongle to supply it with power.
                            There is some software stuff to be set up but it's not that complicated.

                            Alternatively the green stick from here would most likely work OK:
                            (doesn't filter as well though)

                            I suspect the blue Prostick+ would have problems with that interference as well.
                            It might work with the filter offered by FA, but i would rather get the rtl-sdr blog filtered LNA.

                            You really shouldn't need a ModeS Beast, it's overpriced for what it does in my opinion.
                            (more a fan of the AirSpy Mini, which needs a filtered LNA in addition though)

                            Anyhow your problem should be solved by good filtering!
                            Last edited by wiedehopf; 2019-12-24, 11:44.


                            • #15
                              Thanks wiedehopf, I appreciate your help and thinking to solve this problem!

                              Just for fun I've installed the piaware image and tested my outdoor antenna. I do get some hits now! Must be interference indeed. Probably the dump1090-fa is slightly better than the dump1090-mutabilty version from FR24 and picks up a few hits mutability didn't show because of the interference.