Hi folks, please be assured that I do not want to argue away the existence of these dependencies!
> > They don't have a "correct" frequency, only a very stable frequency. > > > > The actual resonance frequency of a rubidium standard depends amongst > > other things on the partial pressures inside the physics package. > > Other issues includes the exact frequency pulling of the > cavity wall, cavity tuning and the mixture of buffert gas > which to some degree compensates the wall pulling. Agreed! But you are talking about things that happen INSIDE the physics package, don't you? Ok, let us assume that there WERE big differences in the physics packages that need to be compensated for. In THIS case the tunable synthesizer would indeed make sense and even more the printed synthesizer settings on the physics packages! If this were the only information available, i would immediatly agree to you! However, when i look into the circuit drawings of my FRK-L it is beyond any question that it uses a FIXED FREQUENCY SYNTHESIZER unlike the HP5060 which uses the described tuneable synthesizer. And that arises the question how Ball/Efratom/Datum/Irvine manage to do it with a fixed frequency synthesizer (even exchange of the physics package) when HP needs a tunable synthesizer. IMHO this can only be possible with one of the two following conditions given: 1) The Ball/Efratom/Datum/Irvine physics packages do have tighter frequency specifications than the HP ones (some orders of magnitude) 2) There is analogue way to pull the atomic resonance to a kind of 'setpoint'. I screwed quite a bit to get my FRK running ok. The lamp temperature was not ok and the plasma excitation frequency was also. I know there are lots of parameters having a subtle but measurable influence on the atomic resonance. Efratom even specified the coefficient for atmospheric pressure, but all of this are very SUBTLE and easily compensated for with the C-field which gives a total +/-10E-9 freqency control range. +/-10E-9 makes about +/-0.7 Hz absolute at the rubidium's resonance frequency. The HP tuneable synthesizer is tuned in app. 1 Hz steps (!) and allows for offsets up to a stunning 1 KHz! Cheers Ulrich > -----Ursprüngliche Nachricht----- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Magnus Danielson > Gesendet: Montag, 6. November 2006 16:01 > An: time-nuts@febo.com; [EMAIL PROTECTED] > Betreff: Re: [time-nuts] Frequency processing scheme of > HP5065 vapour rubidium standard > > > From: "Poul-Henning Kamp" <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] Frequency processing scheme of > HP5065 vapour rubidium standard > Date: Mon, 06 Nov 2006 13:21:50 +0000 > Message-ID: <[EMAIL PROTECTED]> > > > In message <[EMAIL PROTECTED]>, "Ulrich > Bangert" > > writes: > > > > > > >But what surprises us completely is the fact that > different physics > > >packages need DIFFERENT thumbwheel settings to generate > the SAME time > > >scale as seen with the two devices available. > > > > This is because rubidium vapour standards are not primary standards. > > > > They don't have a "correct" frequency, only a very stable frequency. > > > > The actual resonance frequency of a rubidium standard > depends amongst > > other things on the partial pressures inside the physics package. > > Other issues includes the exact frequency pulling of the > cavity wall, cavity tuning and the mixture of buffert gas > which to some degree compensates the wall pulling. > > Cheers, > Magnus > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts > _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
