Right, so this is the situation: I still haven’t obtained my license here in Brazil, but I already have a Baofeng DR-1801 HT that can connect to dmr networks. Therefore I haven’t transmitted yet. But I’d like to clarify some doubts:

  • When I get my license, even in C-class in Brazil, I will be allowed access to some frequencies in 40-10m bands. Should I get a low power QRP transceiver (e.g. uSDX) or go for an used rig from known brands?
  • It’s almost impossible to find a transceiver project with a power rating greater than 10w. What would be the difficulty of, say, copylefting the schematics of an ft-7b?
  • Can I really use a wire thrown over my house (of course, with baluns and stuff) as a monopole antenna or that’s just myth?
  • OneCardboardBox@lemmy.sdf.orgEnglish
    3·
    7 months ago

    1. Hard to recommend, because it will depend on preferences. I went with a QRP Icom IC-705 because I knew I wanted to go hiking and do POTA with it. I will say that 10W can feel very limiting, and it can be tough to make the same contacts that others can easily hit. If down the line you want a stronger transmitter, you’d need to get an amplifier. The overall cost of QRP rig + amp might be more than a “base station” type model with higher xmit power out of the box. Again it all depends on your preferences. At the very least, I’d recommend something with good voice and digital mode performance. Plugging right into WSJT-X or JS8Call for digital is super fun, and I like it a lot more than talking to folks.

    2. Never done a build project for xceiver, so I couldn’t say. All those 10W systems can always be amplified for more output.

    3. That’s called a random wire antenna. It’s what I currently use when taking my rig out on the go. It consists of an antenna line and a counterpoise joined by a 9:1 unun (not balun). Keep it away from other metal parts like roof gutters or fences. The wire length isn’t actually “random”, but you can find tables online where people test for a length that gets ok SWR on several bands. You will still need an impedence matcher (aka “antenna tuner”) to actually get a usable SWR.

      • OneCardboardBox@lemmy.sdf.orgEnglish
        4·
        7 months ago

        Yes, it’s the ratio of how much of the power that you transmit is reflected back towards your rig due to impedence mismatch of antenna <-> radio.

        Ideally you want SWR < 2, but for simple voice modes at QRP power, it’s not the end of the world if you end up in the 2-3 range. However digital modes need a good SWR because they transmit at 100% duty cycle. If I don’t get SWR < 2 for my IC-705 during a digital transmit, the reflected power causes my computer’s USB port to reset. At higher powers it could damage my rig or my computer, so it’s definitely a thing to avoid.

  • HumanPenguin@feddit.ukEnglish
    3·
    7 months ago

    1 up to you. Be careful with spending untill you know you will go further in the hobby. But if you take that advice. You’ll be in a very small group of hams. Most of us have bad buys.

    2 don’t. Not at this stage. Building an amplification circuit is way more complex then it looks.seperation and filtering of feed back in the system is a complex task not advised for a beginner. Sort of why projects don’t include it. It drastically limits the people able to take on the project. Honestly a 2nd external amplifier project. Or purchased amp. Would be a better goal with way less risk of harm to others.

    3 yes but other things then the house may be better. I use a 160m EFHW on my canal boat. With an adjustable unun 64/49/16/9:1 this and a mat auto tuner allow me to use all hf frequencies with low swr. I simply run a 10m pole off the side of the boat. And run the wire into the trees.

    Remember anything like this works. But it is still going to be a compromis. But that is true of most multi band antennas. They will be better at some bands then others.

    I’ll also warn you. What you describe is refered to as a random wire. But is not random. To work with a 9;1 unun it actually has to not match any frequency used. If it is close to half or quater wave on a frequency. It will need a much larger unun. Hence mine going to 64;1

    If you look online you will find recommended lengths. And a list of bands they will work on.

    But for portable work. I found the mixed unun ability much more flexible.