I've designed, simulated and build this simple JFET colpitts oscillator and I couldn't get it to work with real parts. I didn't have BF256B jfet model so I simulated it using some generic one. The circuit oscillates at correct frequency but amplitude varies with time and sometimes it doesn't oscillate at all. I tried to make it oscillate at lower frequencies to see if it would be stable there so I replaced L1 with 10µH inductor, C2 with 2.2nF cap and C1 with 10nF cap and I couldn't get it to oscillate at all (I also tried 2.2nF C1). This is my first time using JFET so I might be doing something fundamentally wrong. Does anyone see any possible issues with this design?