Hi, The magnetic field issue has bothered me a little too, but I don't know whether it has a practical effect. Maybe putting a fan in a plastic or aluminium box close to the Rb might show something - unless someone already knows the effects.
I have a compass on the bench beside the LPRO, and it does drift a bit. What surprised me most was how much the field around the mains transformers changed each time they are switched on or off. Angus. On Wed, 21 Oct 2020 10:04:11 -0400, you wrote: >Hi > >The only issue with the controlled fan approach is that you >have a variable magnetic field as a result. That and the vibration >both can impact the stability of the Rb. Some means of isolating >the fan from the immediate vicinity of the Rb sounds like a good idea. > >Bob > >> On Oct 21, 2020, at 9:31 AM, Luiz Alberto Saba <[email protected]> wrote: >> >> I am thinking in an black aluminium finned heatsink, the size of the base >> plate, and a fan, controlled by an electronic thermostat (sensor direct >> coupled to the heatsink). Is that ok? >> >> Em 21/10/2020 09:40, Wannes Sels escreveu: >>> There are conflicting requirements regarding temperature in Rb's: >>> >>> - For best performance, the rubidium and quartz oscillators must be kept at >>> a high and stable temperature. >>> - For reliability, the supporting electronics must be kept at a lower >>> temperature. >>> >>> The heater takes care of the high temperature. The stability of the >>> temperature can be improved by increasing the thermal mass, i.e. adding a >>> block of aluminium or copper. >>> The electronics can be kept cooler with a heatsink, and forced ventilation >>> if needed. >>> >>> When you stick both the electronics and physics in a small package, this >>> becomes more difficult. For the PRS-10 some form of heatsink is pretty much >>> required to keep the electronics cool enough. Although I seem to remember >>> reading somewhere that the "benchtop" heatsink they offer now is lighter >>> than older units. >>> >>> If the room temperature is not stable enough, you might want to increase >>> the size of the heatsink and add a fan. This reduces the temperature swing >>> inside the unit, while still cooling the electronics, at the cost of >>> increased power draw for the heater. >>> >>> >>> >>> >>> On Wed, Oct 21, 2020 at 5:38 AM Hal Murray <[email protected]> wrote: >>> >>>>> I spent a lot of years buying Rbs and putting them on small heatsinks. >>>> I >>>>> always was disappointed in their reliability. That continued to be the >>>> case >>>>> up to the point that the baseplate temps got into the 40C region. In my >>>>> case, that took a fan . >>>> How well did it work if the heat sink wasn't small? What is your version >>>> of >>>> small? >>>> >>>> Do you have any data (or vague memories) of how much it helps to orient >>>> the >>>> heat sink so the fins are vertical so they encourage warm air to flow up >>>> past >>>> the fins? >>>> >>>> -- >>>> These are my opinions. I hate spam. >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>>> and follow the instructions there. >>>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to >http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
