I’ve ordered a breakout board for Silicon Labs DDS chip, the Si5351, as a starting point for working with signals and forming a homebrew VFO. I think the first thing I’d like to try is putting together a “Polyakov-Style” direct-conversion receiver using KE3IJ’s excellent descriptions, probably for the 40m band, as a place to start. I’ve already got the bulk of the parts in my junk-bin, and a couple toroids are on their way
The folks at Etherkit have put together a very full featured library for the Si5351; I just wish it wasn’t so big! It eats up about 3/4 of the space on an Atmega328 by itself, which doesn’t leave a whole lot of room for other programming. Maybe it’ll be worth me implementing i2c of the Si5351 directly, since I don’t think I’ll be using a lot of the features of the Si5351 Etherkit library to start with.