Hi One interesting thing to do with good / cheap OCXO’s:
If you multiply an OCXO from 5 to 10 MHz, noise goes up by 6 db. If you mix two independent 5 MHz OCXO’s to get 10 MHz, phase noise goes up by 3 db. The same thing happens with ADEV, multiply has no impact. Mixing *should* only get you sqrt(2) of the original ADEV. ( This assumes the ADEV is not coming from a common source like temperature …..) Indeed you could go crazy with hundreds of OCXO’s. Practical setups might run 2, 4, or 8 devices. If indeed they are 20 to $30 sort of parts, four get you somewhere around $100 for the OCXO’s. Mixers / filters / pc boards might double the total cost. Mixing 4 would cut the ADEV by two and drop phase noise by 6 db compared to a multiply. If you had an ideal divider, you could indeed get 6 db better noise at the original frequency. Compared to chasing “unobtanium” grade OCXO’s this could get you low parts in 10^-13 without spending years loosing out on kilo-buck level auctions. ( …. and possibly getting one that does not work ….). Taking the plotted data, you might hit 2x10^-13 at 10 seconds with 4 or 8 OCXO’s. Would you break 3x10^-13 at 1 second? Only way to know is to try it :) Indeed, there are a variety of ways to do the combination. Each has it’s benefits …. Bob > On Jan 22, 2020, at 2:51 PM, [email protected] wrote: > > Hi, I'm testing some of these for a project and they have pretty good > performance! > > Attached is a plot of a very nice one. > > Most are in the mid to high 10-13th Allan Deviation! > > Need to cover to prevent drafts while testing for best results, I just > lay a piece of bubble wrap over the unit on the bench. > > 800ma cold 300ma warmed up 5Mhz sine wave out SC cut with EFC input an > +5v Ref output. > > Very fast warmup! > > Can be adjusted plus minus 1.5Hz, would make a nice offset oscillator for > a DMTD (1Hz offset) > > Also listed as 023-63008, eBay has some and if you Google it there are > some direct sellers. > > Does anyone know what these were removed from? > > Be interesting to know as there seem to be quite a bunch out there! > > Cheers, > > Corby<885ad.bmp>_______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
