John wrote:
I discovered an article on the web that uses an AD835 multiplier chip to square the WWVB signal * * *. I built a five section synchronous filter tuned to 60 KHz to get rid of interference and its output feeds the 835 chip. This all works fine. * * * the 599J won't tune that high so I have to divide this 120 KHz frequency by 2. * * * I've tried to generate a pulse train from the 120 KHz signal and then use a flip-flop to divide the frequency. This does not work well. Apparently generating the pulse train picks up noise and I end up with a 60 KHz signal with fluctuating phase. Now I'm trying to get a Miller frequency divider working
Why are you trying to generate pulses, rather than just squaring (clipping) the output of the 835 in a saturated amplifier? Pulses have less energy and therefore higher noise. All you need is a signal-conditioning squarer matched to the level coming out of the 835 (see Bruce Griffith's pages at <ko4bb.com> for ideas, as well as the Wenzel site and any number of illustrations in Experimental Methods in RF Design -- for example, both Figures 5-46 and 4-45 show complete simple squarers with FF dividers). Even a CMOS gate biased to half-voltage should work fine. I like the NC7SZ74 Dflop for the divider. Half of a 74HC74 works fine, too.
This should be the kind of thing you throw together in 15 minutes and it works first time.
Best regards, Charles _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
