Hi Like it or not, modern crystal packages are mad of metal ( as opposed to glass). The gotcha with metal is that getting rid of *all* of the He is darn hard. That makes a “perfect vacuum” more than a bit tough.
Bob > On Jun 12, 2022, at 7:38 PM, Lux, Jim via time-nuts > <[email protected]> wrote: > > On 6/12/22 6:30 PM, Bob kb8tq via time-nuts wrote: >> Hi >> >> Tear into some of your SC cut based OCXO’s. Take a look at the crystal >> package. For >> bonus points, open up the crystal package. If you have the gear to test it, >> take a look >> at what the gas *is* inside the package. ( Good luck with that :) :) :) ) >> >> If you had the gear and the willingness to scrap out OCXO’s you would find >> that a number >> of fast warmup OCXO’s have a *tiny* amount of He in the package. Measuring >> this would >> be tough ( it’s that small). Go through the thermal modeling and it’s *way* >> more conductive >> (thermal wise) than a *perfect* vacuum …… >> >> Bob > > > And the worst thing is that if your vacuum sealed widget is in an atmosphere > with more He around (like waiting for a launch, in a place that does more He > leak tests, etc.), the He will diffuse into your package and it doesn't work > like expected. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe send an email to [email protected] _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe send an email to [email protected]
