EQUALIZER

Published:2009/6/30 2:14:00 Author:May | From:SeekIC

Designed for use between input jack and microphone of amateur transmitter, to keep bandpass response between limits of about 200 and 3100Hz. Circuit also provides measure of volume compression, improving transmitter efficiency. Construction and ad justment details stress importance of eliminating ground loops and RF feedback. Un is voltage-controlled amplifier in feedback loop, with 741 opamp U2 as compression detector. U2 is biased so output is almost at ground, and no feedback voltage is applied until input to U2 exceeds 0.9 V. U: thus operates in linear mode at maximum gain until output voltage exceeds 0.9 V, when voltage is applied to UI and gain of IC is reduced.-R. Tauber, The Equalizer, QST, March 1977, p 18-20.



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