Hi The market is what dictates how fancy an OCXO gets made. Bottom line is that there really isn’t that big a market (and willingness to pay for super duper TC). If indeed you could do all the fancy stuff and still keep the sell price below $10 then who knows ….
Bob > On Dec 26, 2021, at 1:39 PM, Attila Kinali <[email protected]> wrote: > > On Sun, 26 Dec 2021 13:03:24 -0500 > Bob kb8tq <[email protected]> wrote: > >> The TC of the E1938 as reported in Rick’s papers is way past what >> a “normal” single oven will do (like by several orders of magnitude). > > Yes, but the oven itself is also a much better design than > almost anything out there. Actually, I think that most > single oven OCXO designs out there are rather crude[1], when > it comes to temperature control. Just using the lessons > learned from the E1938 design (i.e. to deliberate control > where the temperature gradients will lie) would improve > many of the OCXO design out there. And that's something > that could have been done without infringing upon the E1938 > patents at all. > > The only other oven design, that I am aware of, that does > something similarly is the 860x inner oven design from > Oscilloquartz. But, as they never mention that they control > gradients, I am not sure whether they were aware of that issue > or whether that's more an outcome of design optimization. > > While we are at it: One of the key points of the E1938 oven > only mentioned in passing[2] is that lateral heat flow, > i.e., heatflow parallel to the designed equi-temperature planes, > needs to be zero. If it isn't zero, then the equi-temperature > planes will bend towards the upper or lower ends of the cylinder > and there would be a net temperature gradient over the crystal. > The two ways how the E1938 achieves this is by using "finite > guard rings" with a gap between the main oven mass and an > additional heater ring along the rim of the oven to compensate > for the heat lost there. Both are very effective, though not > the only ways to achieve this. > > If this "keep the parallel heat flow at zero" would be applied > to more OCXO oven designs, that would already improve them quite > a bit, without the need to go full E1938. > > Attila Kinali > > [1] E.g., the FE-405's inner oven are two resistor next to the > can of the crystal (see attached picture stolen from Bert Kehren). > There is not even an attempt to control the gradients or make > the temperature over the crystal related to the temperature at > the thermistor. > > [2] "The theory of zero-gradient crystal ovens", by > Karlquist, Cutler, Ingman, Johnson and Parisek, 1997 > http://www.karlquist.com/oven.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 > <FE-405B_Osc-3.jpg>_______________________________________________ > 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.
