Hi Erik. What is your counter resolution/gate time? At 1second, the interval difference from 10MHz + 5mHz is 500ps. --mike
On Fri, Feb 18, 2022 at 11:20 AM Erik Kaashoek <[email protected]> wrote: > During long term testing of some 10 MHz TCXO the output frequency seems > to jump within one second 20 mHz ( millihertz) up in frequency every > 110 seconds up and after a 25 seconds, again within one second, the same > amount down. The noise in the frequency measurement was well below 5 mHz > In an ASCII drawing of frequency versus time this looked like: > ________|~~~~|___________|~~~~|________ > Sometimes the high frequency period was very short (some seconds) or > absent but the overall period was within 5 seconds constant > This was tested with 4 different power supplies, although all where > mains connected, not yet tested with battery only, 2 different counters > and two different reference frequency standards. > The TCXO was thermally shielded and testing with some cold air showed a > different behavior for external temperature changes (fast jump away and > slow return to stable frequency) > Also, with thermal shielding removed, touching the TCXO showed also a > fast jump away and slow returning to stable > Measuring the supply voltage did not show clear changes but the used > voltmeter only had 4 digits resolution. > The official spec of the TCXO is much worse so the device is well within > spec but I'm trying to understand why this could happen. > Does anyone know a possible cause for this behavior? > Could this be a small mains supply variation in a 110 seconds long cycle? > Or what else? > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send > an email to [email protected] > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
