Lars, I've broadly understood the aging in the first days to month as being dominated by "bake-out". It's well fit with a logarithmic curve but the effect is so large in the first weeks that it hides the true long term aging (which could well have a different direction).
Tim N3QE On Wed, Nov 16, 2016 at 2:41 PM, Lars Walenius <[email protected]> wrote: > FWIW. Between 2001 and 2011 I run a 5MHz OCXO (in a box). It is a 2x3inch > type without EFC marked OFC MC834X4-009W with date code 97. Probably it was > from some base station testing and it had been sitting in my shelf since > 98. The OCXO were battery backed but at two occasions (2004 and 2007) we > had power fails that drained the battery as can be seen in the graph. > > Just out of curiosity I yesterday put just the first thirty days (like in > the pdf mentioned below) and let Excel calculate the logarithmic function. > If I extrapolate that to 10 years it seems that the drift would be > 6E-13/day but as can be seen in the aging graph it was more like ten times > higher. > > Some days ago I started the OCXO again after it had been on the shelf for > more than 4 years. Enclosed is a graph for the first 7 days. After six and > half days it seems to be a jump of about 1.5E-10 and as I have no > indication of anything else I believe it is from the OCXO. > > /Lars > > >On Mon, Nov 7, 2016 at 10:34 AM, Scott Stobbe <[email protected]> > >wrote: > > > Here is a sample data point taken from http://tycho.usno.navy.mil/ptt > > i/1987papers/Vol%2019_16.pdf; the first that showed up on a google > search. > > > > Year Aging [PPB] dF/dt [PPT/Day] > > 1 180.51 63.884 > > 2 196.65 31.93 > > 5 218 12.769 > > 9 231.69 7.0934 > > 10 234.15 6.384 > > 25 255.5 2.5535 > > > > If you have a set of coefficients you believe to be representative of > your > > OCXO, we can give those a go. > > > > > > > _______________________________________________ > 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.
