CRYSTAL_DISCRIMINATOR_

Published:2009/7/4 4:00:00 Author:May | From:SeekIC

Inexpen sive third-overtone CB crystal used at 9-MHz fundamental serves as high-performance discriminator for VHF FM receiver. Adjust C3 for zero voltage with unmodulated carrier at or near center frequency. Adjust CI and C2 with AF sine wave applied to FM signal generator, using CR0 to check distortion of recovered sinewave. With 1 V P-P IF signal at 9 MHz and 5-kHz deviation, recovered audio will be about 1 V P-P at lower audio frequencies. Good limiter is required ahead of discriminator for AM rejection.-G. K.Shubert, Crystal Discriminator for VHF FM, Ham Radio, Oct. 1975, p 67-69.



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