Hi There are not many single oven designs out there that achieve the stability of the E1938. Of the designs I’m aware of, all use a “correction signal” to get there. Double ovens are a totally different beast …..
Bob > On Dec 26, 2021, at 12:14 PM, Attila Kinali <[email protected]> wrote: > > Hoi Rick! > > On Sun, 26 Dec 2021 08:36:06 -0800 > "Richard (Rick) Karlquist" <[email protected]> wrote: > >> The E1938A has both an ALC loop (common in many oscillators) plus an AFC >> loop, which is exclusive to the patented bridge stabilized circuit. I >> am thinking that maybe the AFC circuit was causing the hump. That >> theory could be verified by disabling the AFC and seeing if the hump >> goes away. The AFC is not necessary just to make the oscillator play >> for noise testing. > > May I ask a heretic question? Does the AFC actually improve > stability? > > I looked at quite a few OCXO circuits (that are still in use) > over the past years. Of them, the E1938 is the only one that > tries to compensate changes within the oscillator at all > (besides ALC). Yet there are many other oscillators that acheive > similar stability values as the E1938. > > You hav written a nice description[1] of how the oscillator does > work and why it should be better, but there are no comparisons > of the ciruit with and without AFC. Or even a standard Pierce > versus the Balanced Bridge. Which for me raises the question, > whether the additional complexity is justified. Especially given > that the bridge circuit halves the available Q and thus increases > 1/f^2 and 1/f^3 noise. > > Attila Kinali > > [1] "A New Type of Balanced-Bridge Controlled Oscillator", > by Richard Karlquist, 1999 > http://www.hpl.hp.com/techreports/1999/HPL-1999-6.pdf > -- > The driving force behind research is the question: "Why?" > There are things we don't understand and things we always > wonder about. And that's why we do research. > -- Kobayashi Makoto > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send an > email to [email protected] > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
