John, VK2ASU, demonstrated GQRX SDR software on a Raspberry Pi using an RTL-SDR dongle to receive 2m stations. Performance was amazingly good for such a small computer.
I had tried something similar recently, on Raspian, but my GQRX crashed on start up. John seems to have figured out that the settings file must be edited before launching to avoid this problem.
My favourite thing is John's cooling arrangement as he finds the Pi gets rather hot when working as an SDR (Software Defined Radio).
John also brought a low cost Android tablet which can be used as a pretty good SDR.
The main talk by Mike, VK2BMR, was the story of his project to build a 2.5KV regulated power supply.
It was a fantastic presentation where Mike described his journey to build a power supply that could easily kill you if something went wrong. In the end he has achieved excellent performance and efficiency. The best bit of these presentations is to hear what went wrong and how it was debugged.
At the trash and treasure I picked up a home brew radio with a lovely reduction drive.
Something I haven't seen for a few years was an OLPC laptop that seems to run Linux quite well. Not sure what happened to these devices, I know they failed to hit the $100 price point at the time but perhaps Raspberry Pi's have taken over from these but I still wish we had a durable laptop version.
A lovely day at Dural again.