Foundations of Amateur Radio

As you might know, I like to transmit with as little power as possible, known as QRP operation. My own station runs at 5 Watts, since on HF, that's as low as my radio will go. I could go lower by turning down the microphone gain, which interestingly is how some radios actually operate, but for now, 5 Watts seems to be a good starting point and truth be told, even though I've been here for a while, I feel like I'm learning something new every day.

One of the largest challenges associated with using low power on HF is propagation on the HF bands which is more fluid than ever. There's plenty of variables. For example, in addition to the day-night cycle, there's Earth's magnetic field, the impact from coronal mass ejections as well as the solar cycle. As that cycle waxes and wanes, or in my case, wanes and waxes, propagation trends are affected on a longer term basis.

There's all manner of tools to explore this. The Australian Space Weather Service is one of many such bodies that create ionospheric prediction maps showing frequencies and their propagation through the ionosphere. Then there's the derivative ones that use this data to declare if a band is open or closed, spread widely across the globe with little in the way of context, like time, or location.

There are tools like VOACAP which attempt to predict the point-to-point path loss and transceiver coverage dependent on antennas, solar weather and time and date. They also attempt to arrive at a so-called MUF, the Maximum Usable Frequency, defined as the highest frequency at which ionospheric communication is possible for 50% of the days in a month. The LUF, the Lowest Usable Frequency is defined as the frequency at which communication is possible 90% of the days of the month.

All these tools have one thing in common. They're predictions and forecasts. They reflect an attempt at quantifying reality. There is a place for this, but my often repeated encouragement of getting on air to make some noise is advice that covers the gap between prediction and reality.

I've long been a fan of using Weak Signal Propagation Reporter, or WSPR as a tool to measure actual propagation. What I like most about it is that it can be used on your own station, using your own antenna, at any time.

It occurred to me the other day that there must be a relationship between a WSPR signal and a voice signal. Not a mathematical one, but one that makes the difference between establishing a voice contact with another station and calling CQ until you're blue in the face.

With that in mind I took a leap and purchased a ZachTek Desktop WSPR transmitter, capable of operating on all the HF bands that my license permits. It was shipped from Sweden this week and it is expected to take more than a month to get to me, likely most of that travelling between Sydney and Perth, but when it does, I'll be able to set up my own in-house 200 milliwatt beacon that will show me just how far my signal goes on the bands that I pick. As an aside, I'm still looking for a similar solution for 2m and 70cm since there are all manner of interesting propagation phenomena associated with those bands as well.

I'm still digging into how I can best gather the reception data to visualise it and I'm working on a strategy that can send me an alert when a particular band is open from my station at such a level that I can look to operating a particular mode, like FT8, or SSB, or anything that I might choose.

The data is public, thanks to the various WSPR reporting systems around, so others in my grid square, likely beyond that, will also be able to benefit from my beacon. I'm considering generating a propagation map from my own station and publish that, but it's too early to say what's involved in making that happen.

Right now I've dived into the rabbit-hole associated with finding a suitable antenna. My current station vertical requires a tuner and I don't think that finding a way to tune my antenna every time the beacon changes band is a good solution.

I suspect that I'll also need to come up with a way to have two transmitters share the same antenna, but I'll cross that bridge when I need to.

Once the beacon arrives, it's my intention to start with 10m as my beacon band using my current antenna, since 10m is on the verge of being useful for my QRP adventures and I must confess, I'm looking forward to making a voice contact with the other side of the planet with my station for the first time in a long time.

What kinds of things can you think of that would benefit from a solution like this?

I'm Onno VK6FLAB