Back to qrss

For some reason, I`m getting back into the universe of QRSS, or very slow Morse code. I goofed around with this for a while, writing some software to record audio and produce the necessary FFTs so that you can read Morse from these incredibly long Morse messages, but lately haven`t done much lately. It`s really just a Colpitt`s oscillator, with a
Back to qrss - schematic

reverse biased LED acting as additional capacitance to tune  the frequency around the nominal crystal frequency. When I built this circuit, I played around a bit with using an Arduino with an digital to analog converter to drive the LED back capacitance, and that worked fairly well. Here`s a timewarp back to that project, in the form of two of my earlier YouTube vids: It worked, but I never put it on the air. But I got to rethinking it a bit more, and thought that maybe I`d assemble a new version and see how much I learned. I`ve got some ideas for improvements: Build in a small dummy load  (just a 50ohm resistor), and add some test points so you can monitor the supply voltage and current from (say) an Arduino. It would be interesting to monitor temperature as well. I also was considering making a better dedicated antenna for it. I suppose I could just use a 30m dipole, but I think it might be fun to try something a bit smaller. Alan did some experimentation with a center loaded short dipole which might be fun, but I`m still pondering that. The micro-power transmitter is fun, and unlikely to cause anybody any anguish, but might also be a bit hard to get any real DX with. So, I started thinking about what I needed to change. Higher voltage, to generate more power. A buffer and power amplifier to generate maybe 100-200mw. And a harmonic filter, so I could be a good citizen. But then I realized something: Hans was offering a...

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