I would not feel comfortable tearing into the unit. Controlling its environment and power to it yes. I did that with a 10811 and a 10544 years ago by drilling a 20 foot hole in my Dallas backyard lowering the units in it with support electronics in place and sealing the shaft with individual sand bags each with a numbered string, so I could pull them out one at time when I had to get to them. Did not have the equipment I have today but I did manage to borrow a 5061A for set up. Here in Miami being right on the water it is not an option. When I relocate from Miami to dryer grounds I may repeat it with a Rubidium. Bert In a message dated 3/28/2010 11:52:14 A.M. Eastern Daylight Time, [email protected] writes:
Bert asked > "why would I want to mess with them at all if they are already under > 1E-12?" Don't know about you, The reason I'd mess with them is cause I'm nuts and can make them even better. And Allan variance is not everything. Have you plotted their Freq change over time with better than 1E-12 resolution? If you are a True NUT, I'm betting you would see things that would make you sick. Things such as line freq spurs, Freq jumps, the effects of: changing temperature, changing PS, changing time, changing Load, partial injection locking to other osc friends around them, and maybe even to the changing moon. Don't forget the Basic Nut Cake pledge. If it can be made better then it is not good enough Or for the more practical answer; Cause I can make mine good enough with some help from two of its friends, named GPS and Rb, that I do not need a Cs primary standard. ws ********************* > Good morning > I have a more fundamental question. Having three 10811-5071 all with Allan > Variance from 1 to 100 Hz well below 1 E-12 one as low as 6 E-13 why would > I want to mess with them at all? > Bert Kehren > ******************** > In a message dated 3/28/2010 8:32:12 A.M. Eastern Daylight Time, > [email protected] writes: > > Hi > > If your zero g axis only works over a 1/100 G range, you are looking at > something other than acceleration. If you have found an axis with a zero, > it > should be a just as much a null at 1 mG as at 1 G as at 10 G's. It's also > possible that your "zero" is actually a minimum below your test > resolution > and higher G's bring it up to the point you can measure it. There's no > guarantee of a zero being there. > > Hitting the oscillator makes it vibrate in all three axis, that's not > going to be suppressed regardless of which way you have it mounted. > > Bob > > On Mar 28, 2010, at 12:42 AM, WarrenS wrote: > >> >> Humm, >> Have to admit, I did not consider that as a possibility before. >> Maybe when I tap on it, its not microphonics after all that cause the > freq to modulate, but the vibration of the inside stuff that is warming > it up. >> For every action there is a reaction and for every nut there is a > wing-it-nut. >> >> ws >> ***************** >> Hi >> >> If that's the result you are getting, you are measuring something other > than G sensitivity. Temperature effects possibly. >> >> Bob >> >> **************** >> On Mar 27, 2010, at 11:02 PM, WarrenS wrote: >> >>> >>> Just a friendly comment about the Zero G turn over point and Vibration >>> >>> Like Zero temp turn over, Special orientation of the OSC ONLY works > good over a VERY SMALL range, (maybe a 1/100 of G change) >>> It would not help vibration and has no effect on microphonics which are > likely a bigger problem anyway. >>> Try taping you Osc, It's freq will go crazy if monitoring it at high > resolutions and bandwidths >>> >>> ws >>> >>> ************************ >>> >>> Hi >>> >>> The concrete basement floor is your friend. >>> >>> Stay as far away from the blower on the furnace as you can. If you have > a drop forge in the basement avoid it as well :).... >>> >>> You will indeed have a seismograph, but not a very useful one. There's > not a lot of G's at seismic frequencies unless you live in an active > earthquake region. The fundamentals of G's and displacement vs frequency > are in > your favor in that respect. >>> >>> Bob >>> >>> >>> On Mar 27, 2010, at 12:42 PM, Stanley Reynolds wrote: >>> >>>> Is the source of the vibration important ? I'm thinking that any > vibration that is not on the same axis as gravity. Walking across the lab > vs a > fan that is out of balance close by. Would a suspended mass mounting help > with vibration isolation and damping with rubber pads and springs or would > that just make a seismograph ? >>>> >>>> Stanley >>>> >>>> >>>> ----- Original Message ---- >>>> From: Peter Vince <pvince at theiet.org> >>>> To: Discussion of precise time and frequency measurement <time-nuts at > febo.com> >>>> Sent: Sat, March 27, 2010 10:51:07 AM >>>> Subject: Re: [time-nuts] Making a HP 10811 better >>>> >>>> Warren, >>>> >>>> If you turn over an oscillator, is the frequency change >>>> completely reversible (to your "under 1e-12 resolution") when it is >>>> restored? Thinking aloud, if an hour-glass is turned over twice, the >>>> final level will be the same, but the grains will be mixed. A quartz >>>> crystal, however, is solid, so hopefully nothing actually moves. >>>> Presumably the zero-G axis is with the axis of oscillation at 90 >>>> degrees to gravity? >>>> >>>> Peter (the "other" one :-) >>>> >>>> >>>> >>>>> Another thing I use it for is to test high resolution Freq meters. >>>>> Using a calibrated wedge that I can then slide under one edge of the > zero-G >>>>> Osc box, I can >>>>> make small, variable, repeatable, freq changes of under 1e-12 > resolution, >>>>> something pretty hard to do otherwise. >>>>> If I want to make BIG changes like 1e-10, I can rotate the box on any > of its >>>>> sides and still use the wedge, >>>>> and for a quick check of new equipment, I just turn the box over > which then >>>>> gives a couple of parts in 1e-9 freq change. >>>>> It makes a weird but simple and indispensable variable freq source > that is >>>>> useful for many things, such as checking the LOOP TC of a TBolt. >> >> _______________________________________________ >> 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.
