Bob Camp wrote: > Hi > > I certainly agree that, say potting the circuit board, would be a lot easier than some of the stuff we have been talking about. I am not sure that it would significantly improve the case. The physical package as a whole, needs temperature stabilization. Double-oven strategies etc. is among them. At the same time it is a heat source, so we need to cool a few wats off it. Except for possibly the resonant cavity, I don't think thermal gradients is as important as stable temperature, where as the crystal(s) of the electronics boards is another story. The electronics might enjoy a cooler and somewhat gradient free environment, but for longer taus most of the effects would be servoed in to the rubidium resonance anyway, so I suspect most of those long-term effects can be focused on the physical package. > My main concern about tearing up the unit is impacting the magnetic shielding. I assume that the outer enclosure forms part of the magnetic shield (at least that's what the data sheets say ...). Good point. Cheers, Magnus

Hi My main concern with gradients would be second order effects on the servo circuit. As you change the zero of the phase detector you get a net short term frequency shift. Gradients on the pc board -> stress on smt parts -> value changes -> phase shift. Bob On Dec 24, 2009, at 8:09 PM, Magnus Danielson wrote: > Bob Camp wrote: >> Hi >> I certainly agree that, say potting the circuit board, would be a lot easier than some of the stuff we have been talking about. > > I am not sure that it would significantly improve the case. > > The physical package as a whole, needs temperature stabilization. Double-oven strategies etc. is among them. At the same time it is a heat source, so we need to cool a few wats off it. Except for possibly the resonant cavity, I don't think thermal gradients is as important as stable temperature, where as the crystal(s) of the electronics boards is another story. The electronics might enjoy a cooler and somewhat gradient free environment, but for longer taus most of the effects would be servoed in to the rubidium resonance anyway, so I suspect most of those long-term effects can be focused on the physical package. > >> My main concern about tearing up the unit is impacting the magnetic shielding. I assume that the outer enclosure forms part of the magnetic shield (at least that's what the data sheets say ...). > > Good point. > > Cheers, > Magnus > > _______________________________________________ > 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. >

Yes, dont start drilling or punching extra holes in the case as some have done, unless you are sure the case isn't mu metal or similar. Optical interrogation of the resonance using lasers would make it much easier to separate the electronics from the absorption cell, it would also allow the rubidium lamp to be dispensed with. However this method can be expensive and it has its own problems to solve. Bruce Bob Camp wrote: > Hi > > I certainly agree that, say potting the circuit board, would be a lot easier than some of the stuff we have been talking about. > > My main concern about tearing up the unit is impacting the magnetic shielding. I assume that the outer enclosure forms part of the magnetic shield (at least that's what the data sheets say ...). > > Bob > > > On Dec 24, 2009, at 7:51 PM, Magnus Danielson wrote: > > >> Bob Camp wrote: >> >>> Hi >>> The original intent was to simply take an existing "cheap" rubidium and do simple things to it. Tearing it into pieces and redesigning parts of it was not anything I originally contemplated. The tight integration of the physics package to the electronics would make this a fairly involved process. >>> >> Well, the main point with that was that while passive temperature stability craze have been raving high here, and into more and more expensive and elaborate propositions, relative simple changes (not without its challenges) would change the equation (amount of heat to cool of) quite noticeably. If money was no object, building no-compromise/prisoners temperature stabilization scehemes around used commercial rubidiums should not be the optimum way to go. Building a Rubidum or Cesium fointain would probably be way better use of the money. Quite a different project thought. >> >> Maybe we need to get back to doable levels, and also consider what changes Rb frequency, why and what can we do to avoid it. >> >> I have been dipping my nose into the literature, to refresh myself on the complex interactions. Lamp intensity in itself is a fashinating topic, while the filtering cells temperature to intensity dependence is another little complex field of its own and that (as I suspected) intensity too pulls the frequency. Oh, and after a quick glaze, I found that the necessary side-peaks needed for servo of C-field exists for Rb-87, so it can be done similar to that of Cesium. >> >> Cheers, >> Magnus >> >> _______________________________________________ >> 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. > >

Hi I'd check the case with a magnet, but I'm not real sure that it would not do something permanent. Bob On Dec 24, 2009, at 9:09 PM, Bruce Griffiths wrote: > Yes, dont start drilling or punching extra holes in the case as some have done, unless you are sure the case isn't mu metal or similar. > > Optical interrogation of the resonance using lasers would make it much easier to separate the electronics from the absorption cell, it would also allow the rubidium lamp to be dispensed with. > However this method can be expensive and it has its own problems to solve. > > Bruce > > Bob Camp wrote: >> Hi >> >> I certainly agree that, say potting the circuit board, would be a lot easier than some of the stuff we have been talking about. >> >> My main concern about tearing up the unit is impacting the magnetic shielding. I assume that the outer enclosure forms part of the magnetic shield (at least that's what the data sheets say ...). >> >> Bob >> >> >> On Dec 24, 2009, at 7:51 PM, Magnus Danielson wrote: >> >> >>> Bob Camp wrote: >>> >>>> Hi >>>> The original intent was to simply take an existing "cheap" rubidium and do simple things to it. Tearing it into pieces and redesigning parts of it was not anything I originally contemplated. The tight integration of the physics package to the electronics would make this a fairly involved process. >>>> >>> Well, the main point with that was that while passive temperature stability craze have been raving high here, and into more and more expensive and elaborate propositions, relative simple changes (not without its challenges) would change the equation (amount of heat to cool of) quite noticeably. If money was no object, building no-compromise/prisoners temperature stabilization scehemes around used commercial rubidiums should not be the optimum way to go. Building a Rubidum or Cesium fointain would probably be way better use of the money. Quite a different project thought. >>> >>> Maybe we need to get back to doable levels, and also consider what changes Rb frequency, why and what can we do to avoid it. >>> >>> I have been dipping my nose into the literature, to refresh myself on the complex interactions. Lamp intensity in itself is a fashinating topic, while the filtering cells temperature to intensity dependence is another little complex field of its own and that (as I suspected) intensity too pulls the frequency. Oh, and after a quick glaze, I found that the necessary side-peaks needed for servo of C-field exists for Rb-87, so it can be done similar to that of Cesium. >>> >>> Cheers, >>> Magnus >>> >>> _______________________________________________ >>> 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. >> >> > > > > _______________________________________________ > 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. >

If you do that and it is mu metal then you'll have to demagnetise it. However this is easier than having to anneal it. If you have a magnetic probe you may be able to test its effectiveness in shielding against the earth's magnetic field. This may be one way of checking if a mu metal case needs to be annealed as a result of rough handling. If you have a dead rubidium then magnetising the case isn't an issue. Bob Camp wrote: > Hi > > I'd check the case with a magnet, but I'm not real sure that it would not do something permanent. > > Bob > > On Dec 24, 2009, at 9:09 PM, Bruce Griffiths wrote: > > >> Yes, dont start drilling or punching extra holes in the case as some have done, unless you are sure the case isn't mu metal or similar. >> >> Optical interrogation of the resonance using lasers would make it much easier to separate the electronics from the absorption cell, it would also allow the rubidium lamp to be dispensed with. >> However this method can be expensive and it has its own problems to solve. >> >> Bruce >> >> Bob Camp wrote: >> >>> Hi >>> >>> I certainly agree that, say potting the circuit board, would be a lot easier than some of the stuff we have been talking about. >>> >>> My main concern about tearing up the unit is impacting the magnetic shielding. I assume that the outer enclosure forms part of the magnetic shield (at least that's what the data sheets say ...). >>> >>> Bob >>> >>> >>> On Dec 24, 2009, at 7:51 PM, Magnus Danielson wrote: >>> >>> >>> >>>> Bob Camp wrote: >>>> >>>> >>>>> Hi >>>>> The original intent was to simply take an existing "cheap" rubidium and do simple things to it. Tearing it into pieces and redesigning parts of it was not anything I originally contemplated. The tight integration of the physics package to the electronics would make this a fairly involved process. >>>>> >>>>> >>>> Well, the main point with that was that while passive temperature stability craze have been raving high here, and into more and more expensive and elaborate propositions, relative simple changes (not without its challenges) would change the equation (amount of heat to cool of) quite noticeably. If money was no object, building no-compromise/prisoners temperature stabilization scehemes around used commercial rubidiums should not be the optimum way to go. Building a Rubidum or Cesium fointain would probably be way better use of the money. Quite a different project thought. >>>> >>>> Maybe we need to get back to doable levels, and also consider what changes Rb frequency, why and what can we do to avoid it. >>>> >>>> I have been dipping my nose into the literature, to refresh myself on the complex interactions. Lamp intensity in itself is a fashinating topic, while the filtering cells temperature to intensity dependence is another little complex field of its own and that (as I suspected) intensity too pulls the frequency. Oh, and after a quick glaze, I found that the necessary side-peaks needed for servo of C-field exists for Rb-87, so it can be done similar to that of Cesium. >>>> >>>> Cheers, >>>> Magnus >>>> >>>> _______________________________________________ >>>> 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. >>> >>> >>> >> >> >> _______________________________________________ >> 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. > >

Hi I suspect that I will wind up with at least one dead rubidium in the course of all this ... Bob On Dec 24, 2009, at 10:19 PM, Bruce Griffiths wrote: > If you do that and it is mu metal then you'll have to demagnetise it. > However this is easier than having to anneal it. > If you have a magnetic probe you may be able to test its effectiveness in shielding against the earth's magnetic field. > This may be one way of checking if a mu metal case needs to be annealed as a result of rough handling. > > If you have a dead rubidium then magnetising the case isn't an issue. > > Bob Camp wrote: >> Hi >> >> I'd check the case with a magnet, but I'm not real sure that it would not do something permanent. >> >> Bob >> >> On Dec 24, 2009, at 9:09 PM, Bruce Griffiths wrote: >> >> >>> Yes, dont start drilling or punching extra holes in the case as some have done, unless you are sure the case isn't mu metal or similar. >>> >>> Optical interrogation of the resonance using lasers would make it much easier to separate the electronics from the absorption cell, it would also allow the rubidium lamp to be dispensed with. >>> However this method can be expensive and it has its own problems to solve. >>> >>> Bruce >>> >>> Bob Camp wrote: >>> >>>> Hi >>>> >>>> I certainly agree that, say potting the circuit board, would be a lot easier than some of the stuff we have been talking about. >>>> >>>> My main concern about tearing up the unit is impacting the magnetic shielding. I assume that the outer enclosure forms part of the magnetic shield (at least that's what the data sheets say ...). >>>> >>>> Bob >>>> >>>> >>>> On Dec 24, 2009, at 7:51 PM, Magnus Danielson wrote: >>>> >>>> >>>> >>>>> Bob Camp wrote: >>>>> >>>>> >>>>>> Hi >>>>>> The original intent was to simply take an existing "cheap" rubidium and do simple things to it. Tearing it into pieces and redesigning parts of it was not anything I originally contemplated. The tight integration of the physics package to the electronics would make this a fairly involved process. >>>>>> >>>>>> >>>>> Well, the main point with that was that while passive temperature stability craze have been raving high here, and into more and more expensive and elaborate propositions, relative simple changes (not without its challenges) would change the equation (amount of heat to cool of) quite noticeably. If money was no object, building no-compromise/prisoners temperature stabilization scehemes around used commercial rubidiums should not be the optimum way to go. Building a Rubidum or Cesium fointain would probably be way better use of the money. Quite a different project thought. >>>>> >>>>> Maybe we need to get back to doable levels, and also consider what changes Rb frequency, why and what can we do to avoid it. >>>>> >>>>> I have been dipping my nose into the literature, to refresh myself on the complex interactions. Lamp intensity in itself is a fashinating topic, while the filtering cells temperature to intensity dependence is another little complex field of its own and that (as I suspected) intensity too pulls the frequency. Oh, and after a quick glaze, I found that the necessary side-peaks needed for servo of C-field exists for Rb-87, so it can be done similar to that of Cesium. >>>>> >>>>> Cheers, >>>>> Magnus >>>>> >>>>> _______________________________________________ >>>>> 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. >>>> >>>> >>>> >>> >>> >>> _______________________________________________ >>> 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. >> >> > > > > _______________________________________________ > 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. >