Hi There are notes here and there talking about MTBF vs temp on this or that Rb.
One simple answer is a servo fan based approach and a target around 45C. Bob > On Oct 5, 2021, at 11:55 AM, Dana Whitlow <[email protected]> wrote: > > I wonder what the detailed thermal model of telecom Rb's looks like. I > cool my PRS-10's > hear sink surface to ~55C with a heatsink, but parts of some other surfaces > of the package > run several degrees hotter. This rather puzzles me, and worries me. > > Dana > > > On Tue, Oct 5, 2021 at 10:46 AM Bob kb8tq <[email protected]> wrote: > >> Hi >> >> Rubidiums are somewhat unusual beasts. They typically have two heated >> zones ( = two ovens) in >> them. One is a bit hotter than the other. Because of the basic physics, >> those ovens are right next >> to each other / in contact with each other. >> >> If you go to crazy with the insulation, the “colder” oven will heat up due >> to heat leakage from the >> “hotter” oven. You need a certain amount of heat coming off the package >> to allow this to happen. >> >> The bigger issue is that there is a pretty big batch of electronics near >> the ovens in the typical telecom >> Rb. Unless you heatsink things pretty well these parts heat up. When they >> do their MTBF drops >> quite a bit. You save a couple of watts of heat (maybe) and loose the Rb >> after a year or two. Not >> a great tradeoff. >> >> Yes, there are a lot of different designs for lab grade Rb’s. There are >> also some really tiny little >> guys running around. Neither category is all that easy to get on the >> surplus market. If you want >> to dive into either of those categories, there are issues, they just may >> not be quite the same. >> >> Bob >> >>> On Oct 4, 2021, at 1:39 PM, Wim Peeters <[email protected]> wrote: >>> >>> Insulation decreases the power consumption. But it will also increase >> the temperature of the electronics. >>> >>> A heath-sink will cool the electronics but will increase the power >> consumption. >>> >>> Or maybe insulate the part of the case that gets hot, and put a >> heat-sink on the other parts? >>> >>> Wim Peeters >>> _______________________________________________ >>> 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. > _______________________________________________ > 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.
