This may be too simplistic, but are the jumps due to aging effects? On Thu, Oct 23, 2008 at 8:00 AM, <[EMAIL PROTECTED]> wrote: > Send time-nuts mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > or, via email, send a message with subject or body 'help' to > [EMAIL PROTECTED] > > You can reach the person managing the list at > [EMAIL PROTECTED] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of time-nuts digest..." > > > Today's Topics: > > 1. Re: Question on crystal jumps (Steve Rooke) > 2. Re: Question on crystal jumps (WB6BNQ) > 3. Re: Question on crystal jumps (Neville Michie) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 23 Oct 2008 23:35:37 +1300 > From: "Steve Rooke" <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] Question on crystal jumps > To: "Discussion of precise time and frequency measurement" > <[email protected]> > Message-ID: > <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1 > > 2008/10/23 Ron Smith <[EMAIL PROTECTED]>: >> The text says the curve of frequency against plate thickness does not give a >> straight line, but has discontinuities in it. These discontinuities they >> call "stepping points" and are a result of edge vibrations coinciding with >> sub-multiple frequencies of the wanted thickness vibration mode. The degree >> of coupling between the wanted and unwanted modes varies with crystal >> dimension. If there is zero coupling, the stepping points should not affect >> the main oscillation. But perhaps even the smallest change in dimension can >> cause it to cross one of these discontinuities and jump to and fro? I >> suspect that crystal sensitivity to stepping or jumping may be correlated >> with its temperature coefficient, although there are other factors >> (including gravitational) that influence frequency of oscillation at very >> small levels. > > I have a counter that seems to exhibit a jump in it's timebase. From a > cold state a fixed frequency connected to the input shows a gradual > change as the unit heats up over an hour or two. Once it reaches a > stable state it will stay in that state for a couple of days and then > it will jump to a new stable state, and stay in that state however > long the unit is switched on. This is repeatable each time I switch > on. I have not observed the jump and there is no data output on the > counter to be able to record the times that this happens. All I know > is that there is a definite little jump after a long period of > stability. > > 73 - Steve > -- > Steve Rooke - ZL3TUV & G8KVD > Omnium finis imminet > > > > ------------------------------ > > Message: 2 > Date: Thu, 23 Oct 2008 03:42:42 -0700 > From: WB6BNQ <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] Question on crystal jumps > To: Discussion of precise time and frequency measurement > <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=us-ascii > > Hi Bob Q, > > Yes Rubidium (Rb) and Cesium (Cs) standards use OCXO's. > > I suppose the way to look at it is the Rb or Cs chamber acts as an > invariant > atomic filter with extremely narrow bandpass (i.e., with an extremely > high Q). > The resonant frequencies of these atomic filters are up in the microwave > regions > and thus do not lend themselves easily to direct comparison. So, a high > quality > standard frequency oscillator is locked in a loop controlled by the > atomic > filter. The OCXO's output is the reference signal out of the atomic > standard. > > I hope this rather simplistic overview answers your question ? > > Bill....WB6BNQ > > Bob Q wrote: > >> Do rubidium standards use an OCXO? >> Bob Q. >> >> ----- Original Message ----- >> From: "Rick Karlquist" <[EMAIL PROTECTED]> >> To: "Discussion of precise time and frequency measurement" >> <[email protected]> >> Sent: Wednesday, October 22, 2008 2:23 PM >> Subject: Re: [time-nuts] Question on crystal jumps >> >> > I'm not quite sure what the question is here, but when >> > we made 10811 oscillators at HP, "jumps happened". Some >> > crystals were better than others, but no crystal was immune >> > from jumps. With good quality crystals, you might be able >> > to put an upper bound on the magnitude of jumps, like 10-9, >> > but not on the time between jumps. I also noticed that there >> > didn't seem to be any correlation between jump activity >> > and stability between jumps. You could have an oscillator >> > with really low aging, say a few parts in 1E11 per day that >> > looked really good for quite a while, but then the frequency >> > jumps. After you've controlled everything you can about the >> > crystal process, the electronics, the oven and the environment, >> > you are still left with jumps. If you want no jumps, go to >> > an atomic standard like rubidium. There are mechanisms that >> > can cause jumps in rubidium standards as well, but good >> > rubidium standards don't jump. >> > >> > Rick Karlquist N6RK >> > >> > >> > [EMAIL PROTECTED] wrote: >> >> I would be very pleased to know when (date and time) anybody >> >> out there happened to record jumps in frequency of crystals. >> >> I have stable (e-07) tuning forks which happen to jump too, >> >> and I don't understand why, even having under control >> >> temperature and air pressure. Sometimes they return to their >> >> prior frequency with another jump, and this could happen even >> >> days later, sometimes they jump and then recover smoothly the >> >> prior frequency in a short time (such as one hour). >> >> I have no idea whether any correlations would exist between >> >> crystals and tuning forks jumps, regarding the causes that >> >> could trigger metastability, and hence I would have a look at >> >> crystal data in order to improve the base for future >> >> speculation. >> >> >> >> Thanks in advance. >> >> Antonio I8IOV >> >> >> >> >> >> >> >> _______________________________________________ >> >> time-nuts mailing list -- [email protected] >> >> To unsubscribe, go to >> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> >> and follow the instructions there. >> >> >> >> >> > >> > >> > >> > _______________________________________________ >> > time-nuts mailing list -- [email protected] >> > To unsubscribe, go to >> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> > and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > > ------------------------------ > > Message: 3 > Date: Thu, 23 Oct 2008 22:00:56 +1100 > From: Neville Michie <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] Question on crystal jumps > To: Discussion of precise time and frequency measurement > <[email protected]> > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed > > Hi, > The EFRATOM LPRO does not use a OCXO, just a straight quartz crystal > oscillator. > The control voltage swings around a volt as the base plate warms up. > The time constant of the PLL that the XO is in must be quite short, a > small fraction of a second > so that the effect of drifting temperature has little effect on the > output. > I guess that all the crystal does is to filter what must be a quite > noisy signal > from the atomic resonance. When I inspected the circuit board I could > not even find the crystal, > it is not in a grand crystal can. > cheers, Neville Michie > > > On 23/10/2008, at 9:42 PM, WB6BNQ wrote: > >> Hi Bob Q, >> >> Yes Rubidium (Rb) and Cesium (Cs) standards use OCXO's. >> >> I suppose the way to look at it is the Rb or Cs chamber acts as an >> invariant >> atomic filter with extremely narrow bandpass (i.e., with an extremely >> high Q). >> The resonant frequencies of these atomic filters are up in the >> microwave >> regions >> and thus do not lend themselves easily to direct comparison. So, a >> high >> quality >> standard frequency oscillator is locked in a loop controlled by the >> atomic >> filter. The OCXO's output is the reference signal out of the atomic >> standard. >> >> I hope this rather simplistic overview answers your question ? >> >> Bill....WB6BNQ >> >> Bob Q wrote: >> >>> Do rubidium standards use an OCXO? >>> Bob Q. >>> >>> ----- Original Message ----- >>> From: "Rick Karlquist" <[EMAIL PROTECTED]> >>> To: "Discussion of precise time and frequency measurement" >>> <[email protected]> >>> Sent: Wednesday, October 22, 2008 2:23 PM >>> Subject: Re: [time-nuts] Question on crystal jumps >>> >>>> I'm not quite sure what the question is here, but when >>>> we made 10811 oscillators at HP, "jumps happened". Some >>>> crystals were better than others, but no crystal was immune >>>> from jumps. With good quality crystals, you might be able >>>> to put an upper bound on the magnitude of jumps, like 10-9, >>>> but not on the time between jumps. I also noticed that there >>>> didn't seem to be any correlation between jump activity >>>> and stability between jumps. You could have an oscillator >>>> with really low aging, say a few parts in 1E11 per day that >>>> looked really good for quite a while, but then the frequency >>>> jumps. After you've controlled everything you can about the >>>> crystal process, the electronics, the oven and the environment, >>>> you are still left with jumps. If you want no jumps, go to >>>> an atomic standard like rubidium. There are mechanisms that >>>> can cause jumps in rubidium standards as well, but good >>>> rubidium standards don't jump. >>>> >>>> Rick Karlquist N6RK >>>> >>>> >>>> [EMAIL PROTECTED] wrote: >>>>> I would be very pleased to know when (date and time) anybody >>>>> out there happened to record jumps in frequency of crystals. >>>>> I have stable (e-07) tuning forks which happen to jump too, >>>>> and I don't understand why, even having under control >>>>> temperature and air pressure. Sometimes they return to their >>>>> prior frequency with another jump, and this could happen even >>>>> days later, sometimes they jump and then recover smoothly the >>>>> prior frequency in a short time (such as one hour). >>>>> I have no idea whether any correlations would exist between >>>>> crystals and tuning forks jumps, regarding the causes that >>>>> could trigger metastability, and hence I would have a look at >>>>> crystal data in order to improve the base for future >>>>> speculation. >>>>> >>>>> Thanks in advance. >>>>> Antonio I8IOV >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> time-nuts mailing list -- [email protected] >>>>> To unsubscribe, go to >>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>> and follow the instructions there. >>>>> >>>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/ >>> listinfo/time-nuts >>> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ >> time-nuts >> and follow the instructions there. > > > > > ------------------------------ > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > End of time-nuts Digest, Vol 51, Issue 73 > ***************************************** >
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