Hi If your OCXO has a stability of +/-3x10^-10 over 0 to 60C (numbers picked to make math easy):
6x10^-10 / 60 = 1x10^-11 per C If the OCXO is 10X better than that (unlike) you are at 1x10^-12/C If the room temperature swings 1 C, you get a 1x10^-11 swing in the OCXO. Keep in mind that the OCXO also responds to things like gradients as much as it does to absolute temperature. If your EFC range is 1x10^-7 for 5V (pretty common): Each 1 mv change is 2 x10^-11. A 78L05 will hold 1 mv over 1C. Roughly 90% of them will hold that over 20C. That’s a cheap regulator for 2x10^-12. A 10 ppm / C reference will get you to 1x10^-13 / C You don’t *need* an EFC at 1x10^-7. Something 1/10 that size is probably good enough. Knocking it down to that level is just a couple of resistors. Way less money than fancy references. Bob > On Dec 11, 2014, at 7:13 AM, d...@irtelemetrics.com wrote: > > Yeah, I suffer from time-nuts digest lag, family lag, day job lag, among > other things. So please excuse delayed responses... > > The oscillator has proven to be relatively immune to 'reasonable' changes in > voltage, as would be expected. About the range of Numbers Bob Camp has > suggested, or maybe even better. The EFC voltage is not an issue at this > point. It was previously, and the solution to that was a low drift 'roll your > own' design. > > It would be nice to replace it with a COTS part, but it looks like there > aren't any available. Thus the reason for pinging the list. Sometimes you all > pull things out of thin air... ;) That said, the LT3081 looks interesting. > At the very least it's easily controllable from an external source. I've got > a few on order, and if it pans out I'll report back here. > > What I'm after right now is in reality small. Temp cycles are somewhat > apparent from looking at what the EFC voltage is doing locked with the GPSDO. > It's on the order 10^-12 range, if I did my math right. It is visible, so it > may be worth trying to fix. Of course, now that Bob has his new CS to play > with anything I do is judged by a completely different standard! ;) > > Again, thanks for the responses! > > Dan > > > _______________________________________________ > 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.
