Here’s a little project I put together on a whim about 18 months ago. It was my tribute to the unlicensed (i.e. pirate) beacon cluster around 4096 KHz. There were several of them operating in full force, with powers ranging from around 100mW to a watt or so a few years ago. Their heyday was about 20 years ago. They were located somewhere in the southwestern deserts of the US, and were powered by batteries and solar panels. The feller who placed and maintained them has stopped their upkeep and, as a result, most, if not all of them, are no longer operational. (There was a small group who also placed these beacons, and I believe they too stopped doing so years ago).

This little beacon, using a commonly available crystal, put out around 30 or 40mW, if I remember correctly, into a 51 ohm resistor as a dummy load. If it were to be connected to an antenna, which will not happen at this frequency, it would need a low pass filter. I haven’t posted the schematic here, for two reasons –

1. I don’t want to encourage unlicensed operation and
2. This particular circuit is a bit of a kludgy design, and not one I’d use anyway.

I’m posting the photos as a reminder that if you don’t have Manhatttan pads, or don’t want to make your own, then so-called “ugly construction” is a very viable way of putting circuits together. If you do it well, your circuits can be quite robust and long-lasting. One of Rex’s MePADS was used for the IC, but everything else was built ugly-style.

In the next overhead picture, you can see the ATTiny85 that keys the transmitter. Above and to the right of it, is a 78L05 that supplies 5V to the chip. Directly below the crystal is the oscillator transistor, which is keyed by the transistor to the left of it. On the right is the PA transistor. All 3 transistors are 2N3904’s.

Before ending this post, there is a key part of ugly construction that is worth mentioning. High value resistors (1MΩ and above) can be used as standoffs. To circuit components, they look like insulators. In this circuit, there are two 1MΩ resistors used for this purpose. I later bought 200 x 10MΩ resistors from Mouser, and will be using them as standoffs in the future. They won’t increase your current draw by any significant amount either. A 1MΩ resistor to ground from a point at 12V potential will only cause an increase in current consumption of 0.012mA. A 10MΩ resistor will have even less of an effect, incurring an increase of just 0.0012mA. That’s 120µA. I can live with that!

Anyway, that’s it. I hope this inspires you to get the soldering iron out and build a little circuit. A simple receiver or transmitter, a novelty circuit, or anything really. Building these little things and getting them to work is fun. Incidentally, if you’re interested in listening out for these unlicensed HF beacons, the best source of information is the forums at HF Underground. The forum you’ll want is the one called “HF Beacons” though there are many other great sub-forums there as well.