Foundations of Amateur Radio

Walking into your shack is often a joyous experience. You take a moment to smile at your setup and, at least mentally, rub your hands in glee anticipating some fun. Well, that is how it is for me, but recently it's been less of that and more of an audible groan at the accumulated cruft that makes it nigh on impossible to sit down, let alone achieve anything fun.

It's not as bad as it could be. I'm forced to keep my station at least operational to host my weekly net, but if that wasn't there, it would have been overtaken by anything and everything finding a flat surface to put stuff on. It got to the point where I had to move some radio equipment off my desk, just so I could pile more stuff onto it.

So, on Tuesday I finally had enough. It was a pretty normal day, waiting for others to get stuff done, deadlines be damned, but I took one look at the shack and snapped. This has happened before and I suspect that it will continue to happen throughout my life, but that day I'd crossed the line.

Before I share what I achieved, I should mention a couple of other things. If you've been here for a while you'll know that I am an unashamed computer geek. Software Defined Radio, or SDR, appears to have been invented just for me, embedded computers, digital modes, networking, data analytics, Linux, Docker, you name it, I'm there. Mind you, this isn't new. It's been true for nearly forty years now, ever since I set foot into my high-school computer lab where I found myself looking at a bank of Apple 2 computers. Then I bought the first computer in my class, a Commodore VIC 20. Life was never quite the same.

This to tell you just how much computing features in my day-to-day.

I have a long term plan to use embedded computers like for example a Raspberry Pi to essentially turn my analogue Yaesu FT-857d into a networked SDR. The idea being that I use my main computer to do the processing and the Pi to control the radio and feed the audio in and out across the network. I want to make it so that you can use any traditional SDR tool with such a radio, and if I get it right, any other radio.

For more context, I'm getting more and more deaf. I swear my SO is speaking softer each day and hearing tests tell me that audio above 2 kHz is pretty much gone. I have been playing with audio signal processing with a view to tailoring the audio coming from my radio into something more audible to me.

On Tuesday I had an ah-ha moment. I could keep waiting until I got all that done and then set-up my shack just so, or I could embrace the analogue nature of my gear and use the mixing desk I have to feed the audio through its on-board audio processing and at least improve my audio experience today, rather than some nebulous future time.

Finally, I purchased a peg board some time ago for the specific purpose of strapping my coax switches to so I would not have to contend with coax all over my desk whilst trying to remember which switch did what when I finally had a moment to play.

All this came together in a new version of my shack, albeit an alpha pre-release, to be treated with extreme caution, if you break it, you get to keep both parts and it will kill a kitten without notice.

To get started, I removed all non-radio stuff from my desk. Including half a dozen computers, a dozen patch leads and adaptors left over from the harmonics testing project, there were monitor cables, USB cables, a variety of power supplies and a stray binder with empty pages.

I found all the radio gear that I really wanted to have on my desk, placed it where I could actually use it and figured out how to connect the audio output from each radio to the mixing desk which also found a home.

Then I jumped on the RF side of things. Getting started was the hardest part. I decided that it would make sense to split the peg board in two, one half for HF, the other for VHF and UHF. I have two coax switches that I use as the entry point onto the board. They're each fed with the antenna coax and each have one port connected to the other. The idea being that during a thunderstorm I can connect the two antennas to each other and isolate the rest of the shack. It won't protect against an actual direct hit, but all charge being built up should dissipate between the two antennas. Feel free to give me suggestions on how better to do this in a shack located on the second floor of a house in Australia. Note that the rules for grounding across the world are drastically different, so don't assume that your laws apply in Australia.

The HF coax side has a strapped down Bias-T which powers the SG237 antenna coupler that's outside. Then there's a switch so I can connect HF to a radio or to a beacon, which I also strapped to the peg board. On the VHF side there's just a second coax switch to select between two radios, but only one is currently connected. I plan to strap my PlutoSDR to the other port.

I powered everything up and couldn't trigger the local repeater. I got out my handheld and tried. That worked fine. I could even hear it on my main radio, but it wouldn't trigger. No SWR issues, I could hear local broadcast stations, but still couldn't trigger the repeater. It took an embarrassingly long time to discover that I had managed to feed the HF antenna into the VHF/UHF side. The SWR was fine because it was triggering the SG237, so, fun.

On the audio side I can now change the compression of a signal, change the low, mid and high frequencies and if I feel inclined change the balance between my ears. Microphone is via the hand microphone, for now. There's no CAT control at the moment and I still need to plumb in the push to talk, or PTT, foot pedal. I also need to move the peg board so RF cables aren't dangling in the breeze, but overall, a massive improvement and best of all, I turned on my radio and it wasn't even Saturday morning.

So, what's your excuse for procrastinating?

I'm Onno VK6FLAB