On Mon, 22 Nov 2004, Mark Jordan wrote: > > I read somewhere that the crystal frequency also depends > on the altitude of operation. Is that true? No, the crystal is hermetically closed. I did open crystals and tried to use them as vacuum sensors (Q based) and it does not work until you are at vacuum levels that are not encountered in normal equipment. Peter _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist