[time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

Bob kb8tq kb8tq at n1k.org
Sun Jul 9 12:09:18 EDT 2017


> On Jul 9, 2017, at 9:35 AM, Francesco Messineo <francesco.messineo at gmail.com> wrote:
> On Sun, Jul 9, 2017 at 2:15 AM, Mark Sims <holrum at hotmail.com> wrote:
>> So far my design is tending towards:  10MHz ref input -> Minicircuits doubler -> Wenzel squarer -> 74AC74 divider -> 74AC04 buffer -> level shifter.  The doubler/divider might not be needed,  but I think it will give a more symmetric output.  I might include a space for a 10 MHz TTL oscillator for non time-nut users... hopefully it might be stable enough over the short time interval for a cal measurement cycle.
> once upon a time, I was experimenting with digital signals to derive
> stable RF transverter
> LOs. I've "found" that feeding a XOR gate with a signal and his
> replica delayed by 2 inverters
> did result in a crude frequency doubler (well it's rather an edge
> detector).

You can do the same thing with a filter on one input of the XOR. Tuning the filter for best 
symmetry is fairly easy. Watching the result on a spectrum analyzer usually is quickest. 


> Since I was going to use the double frequency just to drive
> a divider by two, the actual duty cycle out of the doubler didn't
> matter.
> Frank
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