i need some help plz , i used a crystal oscillator 60MHZ in the circuit below

but the output was 20MHZ even when i used a another crystal, i need an explanation plz, thanx

 

http://img143.imageshack.us/i/fig1q.jpg/

 

Greetings, You will find that you have a 3rd harmonic crystal oscillating at the freq. it was cut for 20 mhz. All overtone xtals will oscillate at the cut freq. in the circuit you are using
Hope that helps

David

 

can u tell me plz, what circuit i need to use to get 60 MHZ ?

 

Look in Google for overtone crystal oscillator circuit. It will have an LC tuned circuit. Yours will be tuned to 60MHz. The active circuit will probably be over-driven to produce plenty of odd harmonics and your LC circuit selects the 3rd harmonic.

 

what is meant by a 3rd harmonic of a xtal oscillator ?

 

nvm guys i figured it out, thanx for helping