M7VXJ Info
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Victor Xray Juliet is the documentation of my [M7VXJ] experimentation in amateur radio, the purpose of this site is to record and share information with other operators. Licenced radio amateur since 2024. 

Radios   
    Yaseu FT-857       Yaseu FT-4X        LilyGo T-Echo     Heltec LoRa32     RTL-SDR       Hack-RF  
Antennas                      Diamond VX30N [2m,70cm]                        DIY V-Dipole [137 MHz]                        Parabolic [1.7GHz]                        DIY Random Wire [14 MHz]                    
             
25th June 2024
Tracking Weather Satellites
137.000 MHz
RTL-SDR

    After building a new V-Dipole using a 3D printed housing and panel mount SMA alongside a SAWbird LNA filter I was able to receive (noisy) APT images from the NOAA weather Satellites. 

    The amount of noise makes me think that there is more work to be done to isolate the radio from background EMF interference.

    11th March 2024
    Dipole Radiation Pattern
    Artwork

      Each antenna has a different radiation pattern, the images bellow show the radiation pattern of a dipole antenna. I was interested in creating the toroid of a dipole as there is certain quality to its convergence and symmetry.

      These renders are aesthetic illustrations and do not portray any useful information, normally scientific visualizations would show dB levels as graduating hues, for this creation I was only interested in the geometric forms. 


      10th March 2024
      Conversations Part I
      Artwork



        While visiting the City Art Centre in Edinburgh, I saw the artwork; ‘Conversations Part I’ by Kate Downie which visualises RF signals as bright lines of colour in contrast to a monotone backdrop. It was my interpretation that the artists was representing the conversations that invisibly intersect the landscape between radio towers as a positive force that connecting people’s lives. 


        11th Febuary 2024
        Logbook
        Yaseu FT-4X
        RSGB GB2RS News GM3HAM Lothians Radio Society
        10:21 - 145.525MHz - GM4DTH (Peter) - Edinburgh 5,9

            
        114th Febuary 2024
        Meshtastic
        868MHz
        Lilygo T-Echo 

          Meshtastic is a software platform which allows LowRa (Low Power, Wide Area) devices to create a mesh network, communicating on 868MHz (in the UK). The information shared includes encrypted text messages as well as GPS locations. 

          We tested two Lilygo T-Echo devices, sharing telemetry and messages to a range of 2km. The theoretical range of these devices is limited by line of sight, so it is possible to make contacts much further.

          I hope to build a custom enclosure for a device using this platform and attach it to the dog's harness so that we can track him on GPS if he ever gets lost. 



          12th August 2021
          Tracking Weather Satellites
          137.000 MHz
          RTL-SDR 

           One of the first antennas I built was a simple V-dipole to receive weather satellite data on 137.000 MHz, I was able to track and record the downlink of a Meteor-M N2 satellite. However, there was too much noise to demodulate the imagery from the carrier, pehaps moving the SDR dongle away from the computer would solve this.


          29th July 2021
          Building a VHF Dipole
          144.000 MHz (2m)
          RTL-SDR

           After experimenting with the antennas that ship with the RTL-SDR I wanted to build an antenna explicitly for the 2m amateur bands which are between 144.000 and 146.000 megahertz in the UK. 

          I calculated that each ‘leg’ of the dipole should be 49cm in length to give good coverage at 145.000 MHz. I connected the dipole to a length of 50 Ohm coax cable and tied everything else together, clamping the antenna to a fig tree trellis. 

          I later realised that this antenna is ‘un-balanced’ as it has no balun to correct the impedance of the coax and the antenna itself, but for a first attempt at making a antenna the results were workable.