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.
<<attachment: _.png>>
_______________________________________________ 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.
