Redditor and veteran upcycler "saveitforparts" has built a radio telescope with a difference: It's been put together primarily from salvaged and dumpster-dived hardware — plus "the cheapest eBay special" software defined radio (SDR) around.
I wanted to start getting into radio astronomy and FTA satellite stuff, so I threw this together with some trash I had hoarded," saveitforparts explains. "Old TV dish, random LNB [Low Noise Block downconverter] found at a surplus store (Axman for anyone from MSP), and a PTZ [Pan, Tilt, Zoom] mount from a security camera (work upgraded cams and was getting rid of old ones). Right now the PTZ is only manual control, but the same surplus store also had cheap Arduinos, so I'm hoping to upgrade to more automatic pointing / tracking once I learn how to use those."
"So far this is super basic, my SDR is the cheapest eBay special that barely goes up to 950MHz. The antenna connection goes through about 5 adapters and is frankly horrifying, and the LNB is powered with two 9v batteries. With the current setup I can 'see' the sun through clouds, and have spotted a couple likely TV sats. I'm not sure if I can do much else until I get more hardware. I've ordered a better SDR ([RTL-SDR] Blog V3) and one of those cheap FTA [Free To Air] boxes to play around with."
While the resulting system is functional, it's not ideal: "To do what you’re looking for without the frustration of never being able to lock most signals, look for a minimum 1 meter dish with a universal H/V [Horizontal/Vertical polarized] LNB," fellow Reddit user ChapadozinhoVermelho notes. "Larger is better. To motorize it, look for a USALS standard horizon to horizon motor. An FTA receiver would then be able to control the LNB and motor and receive signal over the same coaxial cable."
Head to Reddit for the full discussion thread.