Hi The crystal enclosure may (or may not … who knows ..) be back filled with a low level of helium. It does not take much of a backfill for conduction inside the crystal holder to dominate the heat transfer vs radiation transfer.
Bob > On Jun 7, 2017, at 5:21 PM, Richard (Rick) Karlquist <rich...@karlquist.com> > wrote: > > > > On 6/7/2017 1:09 PM, Attila Kinali wrote: >> >> makes the PI loop better behaved. Also the thermal mass of the >> crystal holder is quite small. Especially compared ot the 10811. > > Actually, the oven mass of the E1938A is much heavier than the > 10811 and is made of copper to boot. >> Due to the flat puck design, I assume that the majority of the >> heat going to the crystal holder is due to radiation (unless I >> missed some insulation around the crystal). Radiation, albeit being >> a high "resistivity" transport mechanism, has very low inherent >> "capacitance". And thus the delay associated with this transport >> mechanism is low. > > The crystal case is well connected to the oven mass and gets > heated by conduction. I don't think radiation is a player. > >> There are probably a lot more small design decisions in the E1938 >> that make it such a superb oven. More than I probably will ever >> be able to figure out. And, I still am astonished how well it works. >> Attila Kinalid > > Rick N6RK > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
