What is the bandwidth of the measurement? It may be some broadband noise that is filtered by the OCXO
Didier KO4BB Poul-Henning Kamp <[email protected]> wrote: > >Ok, this surprised me a LOT! > >I used my HP3458A to measure the stability of the Vref output from >an IsoTemp OCXO-107 and the results were anything but stellar: > >The OCXO's Vref has 18 microVolt RMS noise > >For comparison my HP6626A power-supply has 2 microVolt RMS noise. > >Obviously, the Vref only has to be good enough to not be a relevant >source of noise when used on the EFC input. > >If the OCXO has a EFC sensitivity of 10PPM/Volt, then a microVolt >more or less means a 1e-11 change in frequency. > >The Vref is also quite sensitive to the OCXO supply voltage, but >since it was powered by the HP6626A, that's not where the noise >comes from. > >Plot attached... > > >-- >Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >[email protected] | TCP/IP since RFC 956 >FreeBSD committer | BSD since 4.3-tahoe >Never attribute to malice what can adequately be explained by >incompetence. > > >------------------------------------------------------------------------ > >_______________________________________________ >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. -- Sent from my Nexus 7 tablet. _______________________________________________ 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.
