HETERODYNE_FREQUENCY_METER_

Published:2009/7/1 20:18:00 Author:May | From:SeekIC

Circuit consists of 1-2 MHz oscillator Q1, untuned mixer X1, and AF beat-note amplifier Q2. C4 is calibrated to read directly in frequency from 1 to 2 MHz, using accurate unmodulated RF signalgenerator. After calibration, unknown RF signal input frequency is fed into meter for zero-beating with harmonics of calibrated oscillator.Magnetic headphones plugged into J1 make beat note audible. On second harmonic, dial of C4 covers 2-4 MHz; on twentieth harmonic, coverage is 20-.40 MHz. L1 is 65 tums No. 28 enamel on 1-inch form, tapped 20 tums from ground. L2 is 10 tums No. 28 enamel closewound around center of L1.-R. P. Turner, FET Circuits, Howard W. Sams, Indianapolis, IN, 1977, 2nd Ed., p 144-146.



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