Bingo! It's working now!! Thanks to everyone on the thread. Paul, I have to give chops to Bob on this one, even though my experience is the same as yours with respect to the preset triggers. Actually, your comments/question about the "trigger lights flashing" in concert with the 1PPS signal got me looking/thinking and no, they weren't. BTW, my 0.000001 number was meant to be Hz but I left off the units.
Both Bobs (Camp and Albert) were pointing me at the 'input'. So, I drug out the HP5335A manual and re-read about all 4 trigger levels. Auto-adjustable mode allows adjusting the trigger according to the amplitude of the input signal... a sort of percentage trigger mode, i.e. turn the trigger control clockwise to 3/4 scale and you're triggering at 75% of the signal's amplitude. The above trigger changes combined with reconfiguring for 50ohms input signal did the trick. I'm now seeing readings like 0.999 999 983 +0. Thanks again, Jim... N5SPE On Feb 16, 2014, at 4:07 PM, Bob Camp <[email protected]> wrote: > Hi > > If you have a 50/50 duty cycle 1 pps, it’s going to work with a lot of > settings. With a narrow (say 10us wide) pulse, most of the counters have auto > trigger issues. If it’s already known to be reading nutty, trigger is a good > place to start looking. > > Bob > > On Feb 16, 2014, at 4:29 PM, Paul <[email protected]> wrote: > >> On Sun, Feb 16, 2014 at 2:33 PM, Bob Camp <[email protected]> wrote: >> >>> On all these counters, you need to switch to DC input for 1 pps signals. >>> You also need to manualy set the trigger level to something like +1.5V. >> >> >> I can't believe I'm disagreeing with Bob Camp but this is not my >> experience. 99.9% of the time preset trigger works fine and I think you >> should start with that. AC coupling almost always works and is sometimes >> required (with the Rb I think). >> >> I have a 5335A (w/ opt 010+040) and have measured 1PPS on my PRS-10, Fury, >> Firefly and random GPS parts. If the trigger light is not flashing at 1 Hz >> the only thing I've ever had to do is toggle AC coupling or enable 1PPS >> output on the device (or plug it in). Sometimes increasing the gate time >> tidies up the display. >> _______________________________________________ >> 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. > > _______________________________________________ > 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. _______________________________________________ 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.
