You're not using a digital scope with a too low scan rate are you? This will give you aliasing problems & can look a bit strrange. Use an analogue scope or analogue setting to look at the waveform. Also make sure there is effective decoupling as close to the oscillator as possible. Richard P Hi Guys I am trying an 40 MHz oscillator that I got from Farnell ( PN 112-549), but instead of getting a square wave or at least something that is close to it, I am getting a very bad signal. it seems to be oscillating but it looks like it has harmonics on it,with this I mean several frequencies not a consistent one. also it does not look like the wave form the datasheet shows. I am using a 200MHz oscilloscope with a 10X probe. As I never used an oscillator at such a high frequency, I do not know what to make of it, any help would be appreciated. regards Luis -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body