Thank you, Tom - I appreciate the advice. I am using a 74HC390 in the (divide-by-20, square wave output) divider chain, and sure enough, after looking more closely at the data sheet, it clocks on the FALLING edge (I thought otherwise - wrong)! I will stick an inverter in the path and that will probably fix it.
Will update again once that's taken care of. Dave > >Check rising/falling edge times, check trigger levels, check signal levels and >load. Are you DC or AC coupled. How about power supply noise and grounding? >Which edge are you actually triggering on? Is there crosstalk with the Tx line. > >It is extremely unlikely that there's a problem with the UT+ itself -- this >series of Motorola Oncore GPS boards has served the time & frequency community >for two decades with no problems, or jitter, or off-by-100us errors. > >It will be fun to meticulously track down the bug; don't just make it go away >and move on. We will all learn from this interesting problem. > >I'll trade you a perfect UT+ if you give up. At some point we time nuts stop >getting excited about what works and delight in what doesn't, and why. > _______________________________________________ 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.
