IF_NOISE_BLANKER

Published:2009/7/2 2:15:00 Author:May | From:SeekIC

Used ahead of 455.kHz IF strip of communication receiver to provide about 40-dB attenuation of ignition and other noise pulses that can interfere with reception in 2- and 6-meter amateur bands. Two paths for noise pulses, one AC and the other DC, must be balanced for good operation. Resistor and capadtor values in noise rectifier are chosen to select sharp noise pulses in preference to signals. DC noise pulses are amplified by pulse amplifier and converted to AC notse pulses. Settings of pots are optimized for best noise blanking. Circuit requires 12-V supply, which can be obtained from receiver with appropriate dropping resistors and zener as shown for +105 V, or from separate source.-F. C. Uones. Ex. perimental I.F. Noise Blankers, CQ, March 1971, p81-83.



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