...with a 20bit DAC, a suitable voltage reference for that DAC and an HP3458...
On Sun, Nov 6, 2016 at 12:39 AM, Bob Stewart <b...@evoria.net> wrote: > Hi Hal, > > With a 20 bit DAC, even a small aging rate is going to show up. I'll let the > one GPSDO cook for a month or so and see what it shows then. I'll also pull > the data from the log file and see if I can see any correlation between the > temperature and the EFC over time. IOW, for data points separated by 3.5 > days, does the temperature difference between the two point seem to play a > large part of the change in the recorded DAC value. > > The graph was made from the logging data sent to the PC. But, the firmware > doesn't have access to historical data on the PC, so something is needed for > aging calculations. Tom mentioned here recently about the 58503A GPSDO > saving 64 hours of data for it's aging calculations. So, I just added a few > hours to that to get to 3.5 days of history in the GPSDO. > Bob ----------------------------------------------------------------- > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/neo/groups/GFS-GPSDOs/info > > From: Hal Murray <hmur...@megapathdsl.net> > To: Bob Stewart <b...@evoria.net> > Cc: Hal Murray <hmur...@megapathdsl.net> > Sent: Saturday, November 5, 2016 6:23 PM > Subject: Re: [time-nuts] Thermal impact on OCXO > >> The OCXO has been hot for a number of months. > > Then I don't understand why it is still aging that much. > > >> I changed the firmware to save the DAC voltage every 30 minutes for 3.5 >> day > > That's not very long. > > How did you make the graph? You had to get the data out to a place where you > can plot it somehow. If you can do that, why are you "saving" the data? I > assume you have a serial port to a PC or something like that. > > >> The fuzz in the temperature line is, indeed, the HVAC cycling > > You could try putting a box over the unit to see if that slows down the > temperature changes. > > Mostly, you are trying to block air flow. > > > > -- > These are my opinions. I hate spam. > > > > > > > _______________________________________________ > 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. _______________________________________________ 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.