For almost nine months now I have had an itch to get into amateur radio in some way or another. It started when I had been reading about shortwave radio and I wanted to listen to it for myself, so I tried to find a circuit diagram of a simple shortwave receiver that I could build on my breadboard. And it didn’t work. Then a little while later, for some reason or another, I tried to build an SDR (software-defined radio) quadrature mixer to let me experiment with a range of radio encoding methods on one of my Linux computers. And it didn’t work. Then I decided to keep it simple and just build a direct-conversion CW (Morse code) receiver – not much to go wrong there. And it didn’t work.
See the pattern here? Yes, none of them worked. And today, even after I managed to receive and (manually) decode the 60kHz MSF time signal with the help of (the same) Linux SDR program, I still failed to get a simple frequency mixer working in order to tune higher up the LF band. And I only managed to get the time signal experiment working because the sound card in my new computer can sample at up to 192kHz sampling rate, and 60kHz is thus below the maximum tunable frequency of 96kHz, meaning that I practically just had to connect a fairly long random-wire antenna to the line in port on my computer, fire up the SDR, and type in “60kHz” – not much of an achievement there. Heck, even the magnetic loop antenna didn’t work.
So there’s a pattern in the outcome of my amateur radio
projects experiments. What there isn’t a pattern in is in what goes wrong. It’s not like there’s anything wrong with my antenna – for a random-wire antenna with no tuning or preamp, it was pretty damn good at picking up that rather weak 60kHz signal. It’s not like I’m not understanding transistors; I actually managed to figure that one out for one of my projects experiments. It’s not like I don’t know how to calculate the inductance of a coil (unlike what everyone on the ham IRC channel assumed when I said my crystal set wasn’t working). OK, there’s some consistency: I generally manage to either burn out a transistor or have it not do anything at all, and winding coils always seems to end up in a messy loop of knotted wire no matter what tutorial I follow. But other than that, there’s no consistency. Today, I *think*, it was the frequency mixer that let me down; last time it was the HF local oscillator. This time I gave up on the HF oscillator and went with a 1MHz hack just to test that the mixer was working. And I know I can’t stay with the 1MHz oscillator, because ultimately I want to do HF, but you need to be able to wind a coil to build a decent HF oscillator, and I can’t wind a coil (perhaps if I could then that regenerative shortwave circuit that I found online would have worked).
I don’t know why I can’t get it. It’s not that I’m not paying enough attention. I sure am interested in amateur radio and I want to be successful, and I take my time to read through every page that I find and work through all of the calculations. But there’s bits that I don’t understand. I don’t understand transistor amplifiers. I’ve read loads of pages on them, how to bias them, and so on, but whenever I build one the output always stays stubbornly at 0V, and if I do get it to go above 0V it’s normally with a gain of less than 1. Or the whole antenna coupling nonsense. Why can’t I get that? It’s just a damn capacitor; somehow nobody can tell me how to calculate the value of the thing.
Still, it’s not like I was trying to build a super-sensitive extra-selective ultra-high S/N ratio wideband FSK transceiver that could reach halfway round the world. I was just trying to build a practically useless, terribly unreliable, proof-of-concept (and ability) CW receiver that couldn’t even tune the entire band. I didn’t expect it to pull in QRP transmissions from Europe. I just expected to hear a crackle from the speaker, or see something other than a straight line on the oscilliscope. I guess that awful 1.65kHz squeal that came from somewhere deep inside the antenna preamp probably counts as noise.
I know the theory; I just can’t seem to put it into practice.