I found the undocumented PPS signal on pin 6. This is on the "new" $38 unit I just got.
Question: Can anyone measure the pulse? How wide is it and what is the voltage? Here is my setup: Have an older Tek 465 scope that is in only "fair" shape and I see nothing on that pin but milivolt level sine wave of about 60MHz. I can't set the scope to show any hint of a PPS but I know it's there because I routed the scope's vertical amplifier output to channel A of an HP5328 counter, measured period A and I get 999997.5 uSec period. So I'm sure the PPS is going through the scope. But I can't see it so I can't measure it. Next I place the PPS from an Oncore UT+ GPS on Channel A and I get very close to the same period. I suspect my counter needs calibration. Next experiment: Route the FE-5680's 10MHz output to the counter's external clock input. Now the counter is running off the Rb. Then I measure the GPS' PPS and the period is exactly 1 second except for the last digit which some times flips to 1 or 9 (the expected one count random error) So I think the Rb is better than whatever oscillator is inside the HP counter. Next experiments are a long term comparison of the GPS and Rb PPS but I need to know the height and width of the FE5680's PPS. I Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
