Hi Corby, very interesting. I have some questions?
1) it is difficult to read the frequency value on the plot. Can you specify? 2) how do you set the offset of the op-amp trimmer ? 3) do you think is possible to use the -20V on the HP5065A instead the -12V from the DC-DC converter? 4) what frequency measurement system do yo have used for? I am curious to know how you have generate the barometric swing. thanks , Luciano www.timeok.it On Fri 13/05/16 03:29 , <[email protected]> wrote: > HP 5065A Environmental sensitivity > > First here is a comparison between the specified sensitivities of various > > Rubidium units. > > Barometric per mbar Temperature per degree C > > HP 5065A 6.3X10-14 1.6X10-12 > M100 FRK 8.7x10-14 2.4X10-12 > LPRO 1.0X10-13 6.0X10-12 > FE5650A unspecified 1.1X10-11 > FRSC 1.0X10-13 1.1X10-11 > PRS10 unspecified 1.0X10-11 > > As you can see the HP specs are better than the others! > > After much effort I managed to measure the actual sensitivity of a 5065A > on my bench. > It was much better than the spec at 1.55X10-14/mbar! I then installed > a barometric compensation circuit consisting of a sensor and OP amp. This > feeds the C-field circuit in the 5065A. > After alignment the sensitivity was so low that it was below my > measurement noise floor! > > Attached is a frequency plot that illustrates the correction. On the left > is a calibration offset from the Maser of plus/minus 1.84X10-12. The > middle section shows the frequency with the compensation on during > several cycles of plus/minus 35 mbar. The right is with compensation off > and the plus/minus 35mbar excursions. > > Also attached is a schematic of the compensation circuitry. > > Now I'll work on the temperature sensitivity. Poul-Henning has explored > in this area and has some good information to start with. > > Cheers, > > Corby > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts [1] > and follow the instructions there. > > > > Links: > ------ > [1] > http://webmail.timeok.it/parse.php?redirect=https://www.febo.com/cgi-bin/ma > ilman/listinfo/time-nuts > Message sent via Atmail Open - http://atmail.org/ _______________________________________________ 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.
