oscillator output

Discussion in 'General Electronics Chat' started by almoatazbellah, Mar 13, 2011.

  1. almoatazbellah

    Thread Starter New Member

    Nov 24, 2010
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    i need some help plz , i used a crystal oscillator 60MHZ in the circuit below

    [​IMG]

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

    Thread Starter New Member

    Nov 24, 2010
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  3. ve3bbn

    New Member

    Mar 7, 2011
    2
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    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
     
  4. almoatazbellah

    Thread Starter New Member

    Nov 24, 2010
    22
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    can u tell me plz, what circuit i need to use to get 60 MHZ ?
     
  5. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    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.
     
  6. almoatazbellah

    Thread Starter New Member

    Nov 24, 2010
    22
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    what is meant by a 3rd harmonic of a xtal oscillator ?
     
  7. almoatazbellah

    Thread Starter New Member

    Nov 24, 2010
    22
    0
    nvm guys i figured it out, thanx for helping
     
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