FIVE_MARKER_STANDARD

Published:2009/7/21 3:53:00 Author:Jessie | From:SeekIC

Uses 400-kHz DT, cut crystal in NOR-gate oscillator U1A and divider chain U2-U6 to provide calibration markers at 200, 100, 50, 25, 10, and 5 kHz. U2A-U3B are wired as D flip-flops for dividing by 2. U4 is divide by-N counter, with latch arrangement of U5 used to reset selected divide-by5 logic. Out-put of 100 kHz is divided by 5 and then by 2 to give symmetrical 10-kHz output for division by 2 to provide 5 kHz. CM0S CD4000-series logic elements reduce power consumption from 9-V battery to 2.8 mA but allow sufficient switching speed and harmonic energy for good response throughout HF bands.-F. M. Griffee, Frequency-Marker Standard Using CMOS Logic, Ham Radio, Aug. 1977, p 44-45.



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