Hi A shorted tightly twisted pair of heater wire has a *very* low magnetic field. That goes double if you get cute with the way you lay the heater down. I have been told that kind of heater does indeed detune a rubidium. What ever you do, it needs to have a near zero field.
Bob On Dec 24, 2009, at 8:53 AM, Joe Gwinn wrote: > At 10:06 PM +0000 12/23/09, time-nuts-requ...@febo.com wrote: >> Date: Thu, 24 Dec 2009 09:46:13 +1300 >> From: Bruce Griffiths <bruce.griffi...@xtra.co.nz> >> Subject: Re: [time-nuts] Cheap Rubidium >> To: Discussion of precise time and frequency measurement >> <time-nuts@febo.com> >> >> Joe Gwinn wrote: >>>> Date: Thu, 24 Dec 2009 08:57:42 +1300 >>>> From: Bruce Griffiths <bruce.griffi...@xtra.co.nz> >>>> Subject: Re: [time-nuts] Cheap Rubidium >>>> To: Discussion of precise time and frequency measurement >> >> <time-nuts@febo.com> >>>> > > [snip] > >>> >> Distributed heating using wire wound or printed heaters perhaps, but to >>>>> reduce the associated magnetic field bifilar winding should be >>>>> considered. >>>> >>>> Non-inductive power resistors, which are commercially available, have >>>> very low magnetic fields. >>>> >>>> The low-inductance resistors have Ayrton-Perry windings, which are >>>> bifilar. >> >> No, Ayrton-Perry windings arent bifilar. >> >> Classically a flattened helical winding was made on a insulating card. >> An identical winding was then wound in the opposite direction on top of >> the first winding and the 2 were connected in parallel. >> The idea being that the small magnetic field produced by one flattened >> helix is cancelled by that of the other flattened helix. > > True enough - while there are two conductors, they are not close and parallel. > > Anyway, the point is that non-inductive components by definition have low > magnetic fields, and that non-inductive power resistors are common. > > To eliminate the field from the loop of resistors, one can have a linear > string of A-P resistors in series, with a pair of return wires in parallel, > with the return wires on either side of the resistor string, thus reducing > the effective loop area. > > Joe > > > _______________________________________________ > 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.