LOW_DRIFT_7_MHz_VFO

Published:2009/7/6 0:48:00 Author:May | From:SeekIC

Low-drift solid-state design for 40-meter band has maximum change of only 25 Hz from cold start to full warm-up at 25℃. After stabilization, maximum hunting is 5 Hz. Drift is minimized by paralleling two or more capacitors in critical parts of circuit. Series-tuned Colpitts oscillator is followed by two buffer stages, with second providing enough amplification for practical amateur work while further improving isolation of oscillator. Low-impedance output network minimizes oscillator pulling from load changes. Article stresses importance of choosing and using components that minimize drift.-D. DeMaw, VFO Design Techniques for Improved Stability, Ham Radio, June 1976, p 10-17.



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