SIX_ACCESS_TONES

Published:2009/7/20 2:02:00 Author:Jessie | From:SeekIC

Provides 0.4-s bursts at choice of six audio frequencies, for access to up to six different repeaters. Value of C1 in transistor circuit determines duration of burst. AF oscillator uses Signetics NE566V phase-locked loop, with tone frequencies determined by C1 and R1 plus R2 through R7. To adjust initially, remove Q1 from circuit so oscillator runs continuously, connect frequency counter to junction of 0.05-pF capacitor and 1-megohm resistor, set all pots at minimum, ad just R1 for 2500 Hz, set selector switch to position 1, and adjust corresponding control for desired frequency.Repeat for other pots.-G. M. Dickson, A Tone-Burst Generator for Repeater Access, QST, April 1974, p 30-31.



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