If you run a large meteorology bureau, then you probably have access to a wonderful weather radar for scrying the heavens. The rest of us aren’t so lucky. If you find yourself bereft of such hardware, though, you could build your own, taking your lead from [Koakno]’s fine example.The build uses a satellite dome salvaged from an old RV that [Koakno] scored for just $5. Specifically, a Winegard Carryout Anser GM-5000. The motorized parabolic dish was designed to track TV satellites, but here it’s been repurposed into a scanning radar antenna for X-band signals. It’s paired with a cheap SDR—you can use several on the market—which injects an 850 MHz signal, which is up-converted to 10.4 GHz by the low-noise block (LNB) in the GM-5000 and sprayed out towards the weather.Echoes come back from rain, hail, and debris, and get down-converted by the LNB back into an 850 MHz signal that the SDR can capture. The echoes are then plotted on a Plan Position Indicator (PPI) display, showing what’s going on in the atmosphere around the dome. [Koakno] reckons detection ranges span out to 40 km for things like heavy rain, while a supercell hail core could be spotted at up to 60 km in the right conditions.It’s worth noting something important, though. [Koakno] explains that this system is currently in violation of FCC regulations (and probably others around the world), and shouldn’t be used without the proper licenses to access given spectrum. It’s a useful study of how to build a weather radar, but perhaps not something you can just wire together and fire up without getting in a spot of bother.If you’re a die-hard tornado chaser or you’ve just always longed to stare meaningfully at a PPI display, this could be the build for you. We’ve featured other DIY radars before, too. We’d also like to see yours, so when it’s done and written up, fire us a note on the tipsline!