3_20_MHz_CRYSTAL

Published:2009/7/6 0:51:00 Author:May | From:SeekIC

Circuit is series-mode oscillator, but parallel-mode crystals can be used if trimmer in series with crystal is replaced by short-circuit. Adjust feedback by varying ratio of C1 to C2. Use grid-dip oscillator to resonate L1 with C1 when crystal is shorted; then remove short and tune slug of L1 to pull crystal exactly to frequency. R1 should be between 100 and 1000 ohms. The lower its value, the lower the crystal power dissipation and the better is stability. Q1 is 2N918, 2N3564, 2N5770, BF200, SE1001, or equivalent.-R. Harrison, Survey of Crystal Oscillators, Ham Radio, March 1976, p 10-22.



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