DIVIDER_FOR_7_MHz

Published:2009/7/6 3:05:00 Author:May | From:SeekIC

Used after 7-MHz VFO of 40-meter transmitter, to provide 3.5 MHz as required for operation in 80-meter band. Half of 7474 TTL D flip-flop Un is connected in divide-by-2 configuration. U2 provides required well-regulated 5-V source. Q1 clips negative-going portion of 7-MHz sine wave to prevent damage to 7474. Square-wave 3.5-MHz output from U1 is applied to source-follower Q2 which drives class A amplifier output stage Q3. RFC1 and RFC2 are 10 μH. C1 is 6.8-μF 10-V tantalum. Q2 is 100-pF mica. L1 is 41 turns No. 26 enamel spaced to fill entire 7-80-2 core,to give 10 ptH.-S. Creason, A VFO Frequency Divider, QST, Nov. 1976, p 23-24.



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