Oscar M7OJA

Amateur Radio Station

Tag: retrospective

  • 1500km contact on 2m FM

    (Blog posted retrospectively from my old website, NE Ham Radio).

    VHF can work in wonderful ways! I was sitting listening to my radio when I heard a station (signal 5,9) calling CQ. I asked them to repeat the callsign, and I heard “ES8TJM”. They were calling CQ on 145.500FM, and I worked them (receiving a 5 and 9 signal in return).

    The usual range of VHF is “just beyond line of sight”. If you can make a 30 mile contact line of sight, you can expect somewhere in the range of 40 miles radio range. This contact occurred due to an atmospheric condition called “Sporadic-E”. You just have to be in the right place and the right time to benefit from VHF propagation, and I was very lucky to have such a clear contact so far away! I have never worked Estonia on HF either, so a totally new country in the log for me.

    I firstly thought that this might be a “troll” station, but the station I spoke to happily confirmed the contact via email. Definitely worth me sending a QSL card!

    Moral of the story – keep calling CQ! You never know who might respond…

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  • Quick Guide to SSTV

    (Blog posted retrospectively from my old website, NE Ham Radio).

    PC/Laptop
    You can download the free MMSSTV software in order to decode and transmit SSTV images. The software is pretty self explanatory, but you can upload an image and transmit a CQ image, a response to a CQ call, a 73 image, or your own custom text. You can select any mode. The Robot modes tend to be quicker but lower quality. We found Martin 1 to be the best mode (despite taking a long time, the image quality was fantastic).

    Mobile
    You can search on the play/app store for the SSTV software. There are free and paid versions of various tools. I used Robot36 Decoder to decode, and SSTV Encoder to encode. Just a note if you use Robot36 to decode – you will need to change the mode EVERY TIME you receive an image (it defaults back to Robot36). After an image has been received, it is automatically saved to your phone’s memory.

    To transmit using your mobile device, you can load your QSL card or image into the app. You can add some text to the image, and click “transmit”. Remember to select your mode (and announce on the air, in voice, which mode you are using as to avoid confusion). For example “I will now transmit SSTV using Martin 1, please standby, from M7OJA”.

    Identifying On-Air
    Amateur radio operators in the UK must identify themselves “from time to time”. You can usually do this in voice on the air. It is also recommended to print your callsign in all transmitted images (you can add text before you transmit using the mobile app).
    If you are using MMSSTV, you can add an optional morse code identifier on the end of your transmission.

    Other ways to transmit/receive SSTV
    You can connect your radio to a data interface, and then to your computer. Some radios such as the FT-991A has a built in sound card allowing you to connect the radio to a computer using a USB cable. The audio quality will be a lot better, and the images sent and received will be clearer. However, data interface cables and suitable radios are not cheap – you may be better starting off using the mobile app.

    Good luck, and I hope to receive your SSTV image soon! Remember that SSTV is rarely used on the 2m bands, so it is great to drive activity on to this mode. Although 144.500 is primarily for SSB use – you are entitled to transmit FM on this frequency (and it is easier for SSTV operation as more people have access to FM, and you can speak and transmit images seamlessly).

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