20_MHz_PHONE

Published:2009/7/8 2:13:00 Author:May | From:SeekIC

Colpitts oscillator using HEP 53 provides excellent stability with third-over-tone crystal. Power amplifier stage uses 2N4427 in class C common-emitter stage modulated through collector circuit, to develop about 1.25-W output at 28 MHz. HEP 801 FET microphone amplifier provides high-impedance input for crystal microphone and drives HEP 593 IC to give about 1-W AF output. Article covers con-struction and tune-up.-B. Johnston, Little Bill, 73Magazine, July 1974, p 63-64 and 66-67.



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