I had an interesting idea about using a crystal to stabilize a regenerative receiver. I spent a few hours modifying my Piglet regenerative receiver and managed to get some big improvements compared to using the normal LC resonator circuit. A standard ham FT-243 crystal was inserted into the regenerative feedback loop, the receiver tunes from the crystal frequency to about 25Khz down from the marked frequency. You can really hear the circuit "pop-in" when the tuned circuit is resonated with the crystal and CW signals get much louder and less "drifty". CW stations from around the country could be copied relatively easily in the narrow frequency range. After I got the circuit running, I did a Google search on crystal regenerative receivers and discovered that this has been tried by others (no surprise). I added some links to similar experiments at the bottom of my article. Here's the modified schematic: More details on the project can be found here: http://www.solorb.com/elect/hamcirc/pigletregen/index.html The original Piglet receiver worked very well for listening to WWV and short wave broadcast stations, the crystal-stabilized version could probably be used for real ham QSOs, although it would be a challenge since regens are touchy and sensitive to overloading from nearby signals.