It was a tweet from an online friend in the world of amateur radio, featuring a transmitter design published in Sprat, the journal of the G-QRP club for British enthusiasts of low-power radio. The transmitter was very simple, but seriously flawed: keying the power supply line would cause it to exhibit key clicks and frequency instability. It would probably have been far better leaving the oscillator connected full-time and keying the supply to the amplifier, with of course a suitable key click filter.
We’ve all probably made projects that get the job done at the expense of a bit of performance and economy, and from one angle this circuit is a fantastic example of that art. But it’s not the shortcomings of direct PSU keying a small transmitter that has brought it here, but observation instead of
what it represents. Perhaps my social group of radio amateurs differs from the masses, but among them the universal lament is that there is nothing new in a simple transistor transmitter that could just as well have been published in 1977 as 2017.
To explain why this represents a problem, it’s worth giving some background. Any radio amateur will tell you that amateur radio is a wonderful and diverse pastime, in fact a multitude of pastimes rolled into one. Working DX? Got you covered. Contesting? UR 599 OM QRZ? Digital modes pushing the envelope of atmospheric propagation? Satellites? SDRs? GHz radio engineering? All these and many more can be yours for a modest fee and an examination pass. There was a time when radio was electronics, to all intents and purposes, and radio amateurs were at the vanguard of technology. And though electronics has moved on from those days of purely analogue communications and now stretches far beyond anything you’d need a licence and a callsign to investigate for yourself, there are still plenty of places in which an amateur can place themselves at the cutting edge. Software defined radio, for instance, or digital data transmission modes. With an inexpensive single board computer and a few components it is now possible to create a software-defined digital radio station with an extremely low power output, that can be copied on the other side of the world. That’s progress, it’s not so long ago that you would have required a lot of dollars and a lot of watts to do that.
Against that background, a casual reader could be forgiven for missing all this progress and coming away with the impression that amateur radio construction is a world of discrete components with part numbers you would have found in a supplier catalogue from 1975. It is unfair to pick on Sprat alone though (after all, its editor [George Dobbs G3RJV] is a personal engineering hero), this seems to be pervasive across a spectrum of publications in the field.
So why, given that there is a lot of interesting new technology for radio amateurs, do we see so much of what essentially we have seen many times before? The answer of course is that there is a demand for it, and it’s easy to see why that is the case as there is undoubtedly an elegance to making a working transceiver for next-to-nothing from the minimum of parts. There is however a deeper reason for that demand, and it lies in what different radio amateurs are comfortable with. If you know how to make discrete transistor circuits but for example surface-mount soldering scares you and the intricacies of GNU Radio are beyond you, then of course you are going to prefer the safe and friendly world of 1975 when it comes to parts selection.
You might ask why this is a problem, after all if a demand exists and is being sated, isn’t that a good thing? But there are so many more recent technologies to be explored in amateur radio, and maybe the various media outlets that serve amateur radio aren’t fully tapping that demand as well. In this I include Hackaday, because while we are not a radio amateur publication as such it is definitely true that radio amateurs are part of our constituency. A significant proportion of Hackaday writers have callsigns, and we like to cover amateur radio stories. We’ve taken you through some of the fundamentals of software defined radio and tried to cover GNU Radio in detail, but are there any other fields we’re not giving enough attention to? It’s something we’d like to ensure we get right, if there’s a field of amateur radio you’d like us to cover, let us know. As always, the comments are open.