Crystal frequency tuning

Discussion in 'The Projects Forum' started by LDC3, May 19, 2013.

  1. LDC3

    Thread Starter Active Member

    Apr 27, 2013
    920
    160
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
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    Only in a fine tweak manner, you can move the last few digits around. The whole point of the crystal is frequency doesn't shift much. Make one of the 20pf variables.
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
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    This is probably a hijack but a curiosity from my past. In the 60's a class mate was a keen ham operator. In those days one could extract the crystal from the holder itself. He mentioned to me he was up-shifting a crystal by "grinding" it on a flat surface with toothpaste as the grinding medium. I loved the practical bent that ham operators seemed to manifest as a matter of course.:)
     
  4. LDC3

    Thread Starter Active Member

    Apr 27, 2013
    920
    160
    I don't think I want to go to this extreme to change a frequency. After I grind off some of the crystal, I would need to test the frequency. Then propablely grind off some more, remount the crystal, and so on ..... :)
     
  5. MrChips

    Moderator

    Oct 2, 2009
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    Depends on how much you want to change the frequency. Crystals are stable to about 5 ppm. You can tweak it around 50 ppm, 0.005% that's it.
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
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    That first circuit re post #1 has a pot to adjust the xtal drive, that pot will probably allow some trimming of freq itself.
     
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