On Sun, 19 Aug 2018 15:27:03 -0700 Ralph Devoe <rgde...@gmail.com> wrote:
> Thanks for the notes on the FS740. I missed it back last November. It > looks so user-friendly that I might have to get one. Most SRS stuff is > really well done. Yes, indeed. All SRS schematics I have read looked really like someone who knew what he is doing did the design. The newer designs also include comments in the schematics about the design decisions, which is really nice IMHO. > The question I have is whether it is practical to get to the 10(-13) level > with a good Rb and a good GPSDO. The Rb's aging rate is low enough, but, as > Corby has pointed out, they are sensitive to temperature / pressure so > that they can move faster than the GPSDO can correct for. I'm not clear how > far this can be pushed. If you have a HP5065 and use Corby's modification, then getting to 1e-13 should be reasonably easy. If you have a PRS10 or LPRO, you will have to do temperature and probably also pressure compensation to get to the stability needed. But I cannot say whether you can actually get down to those numbers. I am currently building a setup to measure the temperature and pressure dependence on an LPRO, but it will take some time until everything is ready, and then it will take a couple of months until I have reliable data. BTW: I recommend using some digital scheme for offset frequency generation and not touching the C-field adjust of the Rb. Either a simple DDS with enough bits should do, or a divider scheme like Rick's synthesizer[1]. Attila Kinali [1] "A narrow band high-resolution synthesizer using a direct digital synthesizer pollowed by repeated dividing and mixing," by Rick Karlquist, 1995 http://www.karlquist.com/FCS95.pdf -- <JaberWorky> The bad part of Zurich is where the degenerates throw DARK chocolate at you. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.