The more i read, the more i loose trust in any GPSDO.
There are warnings that the used OCXOs are likely to be at the end of their lifespan in terms of frequency-trimming voltage range.
So they might soon not be trimmable to 10.000 000 MHz anymore?
This is a risk, I've just bought one off e-bay as I think there are ways to mitigate the risk. First, I can measure the control voltage to see where it settles within the return period (though the cost of shipping it back to China may be prohibitive) - if it really is at an extreme value I think the seller would probably replace it.
Secondly, I've acquired quite a few new old stock OCXOs off ebay over the years so in future it may well be possible to replace the OCXO though this may require some sort of daughter board.
Also, the life span of around 10 to 20 years for OCXOs is based on worst case, drift generally decreases with age and with good fortune it may be fairly stable well within range.
If you're really worried then get something like Leo Bodnar's one which uses a new device so won't have aging issues but of course the device is just a TCXO and won't have the same stability as a double-oven OCXO.
The datasheet on the 8863 OCXO has aging at 10^-8 per year with tuning at +/- 0.3 ppm so 0.3*10^-6/10^-8 gives a tuning life of 30 years - the drift on the lower option model is 1.5 *10^-8 so this would be 20 years.
The Lea 5T GPS module was launched on the 2nd April 2008 :
http://www.insidegnss.com/node/600So these GPSDO cannot be more than 10 years old so by my calculation they should have 10 to 20 years of life left in them.
These modules have been superseded, perhaps by rubidium units or other means I don't think they have, by any means, reached the end of life.
I've just also checked on the data sheet for the GPSDO itself and this is dated Nov 08, there may have been revisions but it all points to an age of less than 10 years for something with a life of potentially double that.