GGAPBE96 said:If an oscillator has multiple positive feedback paths,
it oscillates at plural frequencies or at a certain frequency??
LvW said:If there are parasitic oscillations in crystal oscillators, they are caused in most - if not in all - cases not by a secondary (unwanted) feedback path but by the different modes the crystal can operate.
Most mechanical and EM oscillators have "modes". A crystal at least has different overtones, I guess, you have heard about it before.I can't understand the words "different modes the crystal can operate"