Getting On The Air With A 10-Minute-ish Ham Transmitter

Artificially constrained designs can be among the most challenging projects to build, and the most interesting to consider. The amateur radio world is no stranger to this, with homebrew radio designs that set some sort of line in the sand. Such designs usually end up being delightfully minimalist and deeply instructive of first principles, which is one reason we like them so much.

For a perfect example of this design philosophy, take a look at [VK3YE]’s twist on the classic “10-Minute Transmitter”. (Video, embedded below.)

The design dates back to at least the 1980s, when [G4RAW] laid down the challenge to whip up a working transmitter from junk bin parts and make a contact within 15 minutes — ten for the build and five for working the bands. [VK3YE] used the “oner” — one-transistor — design for his 10-minute transmitter, but invested some additional time into adding a low-pass filter to keep his signal clean, and a power amplifier to boost the output a bit.

Even with the elaborations, the design is very simple and easy to understand. Construction is the standard “ugly style” that hams favor for quick builds like this. There are no parts that would be terribly hard to find, and everything fits into a small metal box. The video below shows the design and build, along with some experiments with WebSDR receivers to check out range both with and without the power amplifier.

Seeing these kinds of builds really puts us in the mood for some low-power action. Could something like this pop up in “The $50 Ham” series? Quite possibly yes.

30 thoughts on “Getting On The Air With A 10-Minute-ish Ham Transmitter

      1. I’m not following, ‘coz VK3 says “Aussie ham in Victoria” and it’s the Y that (used to?) says he had an advanced license rather than standard.

        But everyone seems to be missing the spiderman joke, so I’ll point out it was a spiderman joke, because spiderman got bitten by a spider and his name was also Peter Parker, the dude not the spider, so that’s why it’s funny, because people also call spiders bugs, and I said bug in a metaphorical sense while implying it in a physical sense as a pun, wherein it could be imagined to be an actual bug biting him and transforming him into hamradioman or something. This is meant to create a slight moment of nervous tension as your brain hits a kind of dichotomy of meaning, then leading to a release when you figure it out, resulting in spasms of the diaphragm. PSA: A year 2000 study found that people with heart disease were 40 percent less likely to laugh and be able to recognize humor in a variety of situations, compared to people of the same age without heart disease

  1. Save us from the world where people think videos are a sutiable way to present technical material. There’s a difference between someone showing a specifc technique, and so.eone too lazy to write a bit about a project.I

    Videos say a lot about the creator, and a lot about the viewer, and their all getting a pass.

    If the schematic isn’t viewable without viewing a video, we shouldn’t even begin to give credit to someone.

    And there’s a big difference between people who know what they are doing who try for simplicity for a challenge, and people who go for absolute simplicity because they are beginners. Beginners don’t know that a missing tuned circuit (the “too difficult coil I mentioned previously) will impact the output signal, while the advanced was going to use an antenna tuner.

    There’s no precess to “get into print”, no third parties putting projects in context (except when the internet plays along and hypes some project without crticism), no real challenge to what people are doing.

    There’s also a big difference between people who are beginners but who are good explorers, “hackers” , who can relay something to others, and beginners who know little but who feel they should be expert. There’s no process to filter the latter out. “Let’s do a video” let’s an awful lot of people in.

    Peter Parker is no beginner, but I don’t respect people who make videos where a written article is more approoriate. But others who get hyped are beginners.

    1. OK, grandpa. I doubt you’ve ever tried to edit a video together in your long life, as the entire idea of presenting a video being the “lazy” option versus writing an article is frankly laughable to anyone who has.

      It’s not a matter of laziness, it’s a matter of connecting with the intended audience. Nobody cares that you authored a 10-volume treatise on Hertzian Waves in 1905 after making a cat whisker detector using galena that you mined from the ground using your bare hands. Numerous people below their mid 20’s, which you apparently last were towards the end of World War II. And people in that age demographic trend toward getting information in audiovisual form.

      I also long for the days when people bothered to do extensive textual write-ups on various things. Not a week goes by when I’m not trying to look up information about this or that game’s inner mechanics, and I end up having to resort to a minute’s worth of information buried in a 15-minute video from a reedy-sounding tween intermingled with entreaties to “Like, comment, subscribe, and ring that bell, fam.” It’s frustrating, I get it.

      But I also get that I do not lie within the audience intended by the creators of said videos.

      Now go have some prunes, drink some Ovaltine, and yell angrily at the TV some more.

      1. Mog, you sound like a bit of a grandpa yourself, knowing about Hertzian waves, and catswhisker diodes etc. :)

        Seriously, some people learn better from video, some from text. My wife learns better from video, I learn better from text). Different stokes for different folks. Neither is better or worse, excepting that many millennials are a bit lazy when it comes to reading!

        1. Although I don’t know where Michael Black is located in the world, it doesn’t sound like a particularly Swedish name, and I’m pretty sure the HaD editors can confirm that he and I are two distinctly different users of the site.

          So to that end, I’ll interpret your apparently professional analysis as a compliment that I can argue bitterly in a crotchety, misanthropic manner from exactly the opposite direction of Mr. Black that it’s indistinguishable from his own ramblings, and wear it as a badge of pride.

      2. That saying a picture is worth a thousand works is kind of hard to read when you try to freeze frame a video which is why books are written in the first place. When you can put each in hand, some written text and a little photography goes a hell of a long way. Most of the videos I have watched do little for instructing on account of the person doing the video is very illiterate in speech or speaking a dialect and language that is all but understandable. It’s pretty hard to make sense of someone that has no comprehension of how to communicate clearly or form a true sentence without stuttering or relaying their thoughts. Same goes for anyone that cannot write down thoughts and make a plausible explanation in words. As for extensive text, I too am an old fart that spent so many hrs. at a work bench reading about electronics and getting frustrated because back then, that was how it was done period. Time still waits for no one and the older one gets the more it matters. Which is why I suppose a lot of us simply just take up a fishing. Or watch YouTube videos.

    2. I’m with the others here, but I can see your point. I tend to prefer text myself. But in this case you don’t need a circuit diagram, all the components and ‘traces’ are flapping around obviously connected to each other. So if you understand electronics you can look at it and see how it works anyway… So this video doesn’t really need more, heck if you didn’t want to see the challenge element done the basic concept of this setup is documented in many sources..

      I think everyone would rather have text based material as well IFF this was some hideously complex beast, with heaps of layers all full of complexities to deal with – as referencing to a spot in a video later for that detail you want to look up again is hell, but text is just a simple search (if you remember the proper terms for things at least – its a slightly trickier search if you don’t remember what its called, though I’d still say easier than scrolling through a video).

      The nature of video (or usually better) a live in person lecture is that emphasis on the key elements and connections comes in an easy to spot form (with a decent lecturer) – how each element interconnects, the pitfalls to avoid, the tools needed to understand each part get presented in a structured and interlinked way, where a book wouldn’t actually throw in that reminder to last years lemma/proof or whatever the new topic interacts with in the same way. I still prefer just reading the material myself in general, but having a more expert human share their knowledge more directly is often far more informative than reading their book…

    3. Michael. I gather you don’t much like the video medium.

      That is your prerogative and you’re not compelled to watch any of mine.

      But apparently 16 000 subscribers do. Not just once but repeatedly with over 5 million views total.

      Video is not new for imparting technical information; decades before the www and YouTube were even thought of outfits like Bell Telephone Labs were using video to provide instruction on matters like standing waves in the 1950s.

      I take it you prefer extended articles. You may be unaware of my work here. Even the old fashioned type that appear in dead tree magazines and go through technical editors, etc. I can point you to over 100 written for one magazine alone over a 30 year span. A list, with some linked, is here. The transmitter referred to in the video might even become a written article in the future.

      Sometimes though even magazine articles aren’t enough for everything that needs saying on a topic. That’s where books come into their own. I’ve written some of those too. Full details here:

      Getting back to videos, I make no apology for making them on topics that interest and inspire people. There will be many more. Knockers and curmudgeons will continue to have no influence.

      While the ‘old guard’ might be more interested in keeping people out, ‘letting an awful lot of people in’ sounds like an excellent idea for amateur radio. Especially given concerns about the cohort’s ageing and even skill shortages in RF-related industries.

      Peter VK3YE

    4. “Save us from the world where people think videos are a sutiable way to present technical material.”

      Agreed. Regardless how one learns best I think there is a practicality to having something in text form because you can more easily index, search it, read and re-read the parts you need.

      There are also those of us who take information in more easily from reading and those who are better at listening. It’s nice to have both so that everyone can be satisfied. But our society has long been biased towards those who learn verbally. Our entire set of life opportunities are based on our performance in 13+ years of schooling that consists almost entirely of watching teachers stand in front of a room droning on. Personally I think I could have done a lot better given a stack of books, a syllabus and a phone number to call if/when I have a question.

      Some people I know would have done better with more lecture hours and no books at all. I’ll never understand it but people are different and work differently.

      The internet was a great thing for us visual learners. We finally had a place where we had the benefit. But then bandwidth increased, videos became practical and our oasis is slipping away.

      The really annoying thing is when audible learners complain. They have the advantage 99% of the time but feel so slighted when the rest of us get a turn! I suppose when you always have things going your way you don’t learn to deal with the opposite.

      I remember a class I had in college. The professor wrote his own textbook so his lectures basically followed the book. A reader could tune him out, read the book and do fine on the tests. I only really went to class in case there was a quiz and I loved it. There was another student in the class who complained very loudly about how much he hated that. I could have decked him.

      Also, reading text is a whole lot easier to get away with when you are supposed to be working than watching videos.

      Oh well.

      “but I don’t respect people who make videos where a written article is more approoriate”

      That’s going too far. First, VK3YE has a great amount of skill and knowledge that deserve respect. Second, none of us paid him anything. He didn’t owe us text or a video. Making and sharing content deserves respect and appreciation. The same goes for many other people out there that make good videos.

      Besides, while I’m about as visual of a learner as a person can be I am learning to appreciate videos too. Give me text any day if I am trying to really thoroughly understand a topic. But sometimes it’s nice to just relax with a video, and still learn some information even if not all of it.

      And watching how-to videos of things like car repairs… that’s great! It’s often hard to visualize just how things go together from a flat, static illustration.

    5. You’re gonna get eaten alive for this but I wish I’d commented earlier! Didn’t have the cahoneys in the end.

      There’s a hand drawn schematic now not sure it wasn’t loading earlier.

      I agree I was scoffed at earlier today for recommending a book to some students. It’s all YouTube videos and apps now.

  2. 7MHz doesn’t seem much of a challenge in the age of GHz processors, where even cheap microcontrollers easily clock at several 100 MHz.

    And as everybody has a Raspberry Pi in the dustbin, this challenge could be solved with software really quick.

    Nevertheless a nice example of good old analog technology. Keep this in mind when the apocalypse comes, and always have a gas powered soldering iron and a hand cranked generator in reach.

    1. That’s awesome that you can do it all in software. Please post your article of a CW transmitter with a Raspberry Pi that produces a legal CW signal on the 40m amateur radio band. The Raspberry Pi needs to connect a GPIO directly to the antenna because you have said “this challenge could be solved with software really quick”.

      Looking forward to it.

    1. The good news is there’s a hack you can do to help everyone out with this: grab a screenshot, clean it up in your favorite image editor, and post the link to the image in a comment here.

      I’ve done this one (and added it to the article).

  3. While vastly better than the Sprat version, the low pass filter does *NOT* meet spectral emissions requirements anywhere in the world if used at 7 MHz. This is a chronic problem with old QRP designs and even recent Sprat designs :-(

    It appears to be a ~10 MHz LP filter According to Elsie, it’s only down 20 dB at the 14 MHz 2nd harmonic and 40 dB at the 21 MHz 3rd. Requirement is <-43 dB.

    By all means build it, but fire up Elsie and design a better filter. A 5 element Cauer will fit the same PCB footprint as a 3 element Butterworth and can reach <-60dB for the 2nd harmonic. So you can easily fix the bad filters on ebay kits from China such as the Pixie 2 by WA6BOY.

    A search of EEVblog will turn up before and after spectra for the Pixie 2.

    1. Reg, thank you for posting this. I’ve read that transceivers like the Pixie, BITX and others were sloppy with regard to signal purity, so it’s good folks like you are watching out.

      Could you perhaps post a comment on the YouTube page as well?

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