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

[Mark Sims]

I think it will take some testing to see if using an analog frequency doubler or XOR digital doubler will provide the best performance.   My gut says the analog doubler ($6) will work better than the ($0.20) XOR doubler.  I hope the XOR doubler works well.

It would be even better if the doubler / divider is not needed and one can just square the input 10 MHz.   The HP cal procedure says to feed a signal generator with a 10 MHz 50% duty cycle square wave to the counter.   Most signal generators don't tend to be all that precise about how well they do the 50% thing and HP does not specify a tolerance on the freq or duty cycle (or even which signal generator to use).  If the counter's internal cal routines do things right, it should be able to null out the asymmetries.