I use to have a similar on from GR but was lost in a fire. It had a large GR metal name plate on one side.
I sanded and varnished the box and had it on display for quite a long time. GR was great at stretching the mechanical limits of material to get electrical specs. -pete > I have a General Radio 100KHz crystal oven that is inside a crafted wood > box. The oven uses a mercury thermometer with a pair of wires sealed in > the side to implement a bang-bang servo. The wood box will thus smooth out > the square wave heat pulse. I think it came from something like an LR-1 > Navy signal generator as a calibration standard. I need to put an > oscillator circuit on it in order to characterize its behavior. It's on > the FIFO to-do stack... > Don > > Arnold Tibus >> Ed, >> and the big group >> >> I did run such a 10811 without the outer heater connected and without >> any insulation around as replacement for the original insulation and box >> but I did not see any fluctuations beside the normal behaviour of a >> 10811. >> >> (I have to admit that I did not yet run precision records, neither for >> the >> heater current nor for the frequency output. I see what I have to do >> soon!) >> >> This model is obviously adjusted inside to work best in an encreased >> environment of around 40 to 45 deg. C . >> >> I think as Ulrich does explain, blocking the heat flow significantly >> must >> deteriorate the regulating loop parameters. The life time of the >> oscillator >> electronics outside the stabilized crystal element will as well >> decrease... >> >> A good idea in fact to put the standard in a stable area and very slow >> varying temp range of around 15 deg. C underneath the house >> fundaments...I will think about! >> >> Did anybody ever think to apply wood as stabilizing element around an >> oscillator? Wood behaves a bit strange, it is on one side a not bad >> insulator and it does have as well a quite high heat storage capacity! >> >> (Oak with around 2.4 J/g, K., Lambda 0.17 W/m.K,, >> Pine around 2.7 J/g.K., Lambda 0.14 W/m.K. >> Water around 4.18 J/g.K., Lambda 0,604 W/m.K. >> Copper has 0.385 2.4 J/g, K., Lambda 401 W/m.K. at 25 deg. C. ) >> I consider wood a very intersting material, cheap and easy to work... >> >> Arnold >> >> >> >> On Thu, 11 Jun 2009 09:22:00 -0600, Ed Palmer wrote: >> >>>Ulrich, when you changed the thermal characteristics around your 10811, >>>how 'crazy' did it become? >> >>>According to your theory, there should be differences in the schematics >>>of the oven controllers between the single and double oven variants of >>>the 10811. Last year I picked up a couple of those double oven 10811s >>>from China that had the outer insulation removed. I wonder if I could >>>see any anomalies in its operation with no outer insulation and only the >>>inner oven operating. >> >>>Ed >> >>>Ulrich Bangert wrote: >>>>> I'm not talking about crystal ovens, I'm talking about >>>>> timekeeping kit in general: how to filter high frequency >>>>> temperature fluctuations out, so the PLL does not have to >>>>> deal with them. >>>>> >>>> >>>> Ok, but in this general case you have to accept the fact, that >>>> filtering >>>> high temperature fluctuations is only ONE part of the engineering job. >>>> The >>>> second task (which I tried to point at) is: When you do already have a >>>> closed loop temperature regulation system inside what you plan to >>>> built >>>> around it, then you need to manage the filtering without mal >>>> interaction of >>>> the local temperature controller with your additional filtering stuff. >>>> The >>>> art is to make the closed temperature loop inside see only smaller >>>> temperature fluctuations but No changes otherwise. >>>> >>>> If you apply an overall change in temperature insulation to the >>>> ambient >>>> you >>>> will make the work of the inside temperature controller a lot harder >>>> because >>>> it is not prepared for that. In the aluminium box that i wrote about I >>>> have >>>> for an experiment replaced the air between the 10811 and the outer box >>>> with >>>> a material that has a significant lower temperature conductivity than >>>> standing air. You can easily watch the temperature controller go crazy >>>> with >>>> that. For a second experiment I have replaced the air with a material >>>> having >>>> lots more of thermal conductivity than air and you can watch the >>>> temperature >>>> controller go crazy with that too. You don't need sophisticated >>>> temperature >>>> measurement equipment to see the controller go crazy, just watch the >>>> frequency of the oscillator. This will tell you all about it. >>>> >>>> Things are different, if you have an influence on the controller's >>>> regulation parameters (which you do not have with a ready bought >>>> device). If >>>> you do have, then your additional provisions for filtering and >>>> insulation >>>> can easily be included into the thermal model that the temperature >>>> controller has to handle and will lead to different operation >>>> parameters of >>>> the controller. That will of course work and that is why I compared >>>> your >>>> suggestions to designing a new oven (for xtal or rubidium or >>>> whatever). >>>> >>>> Best regards >>>> Ulrich Bangert >>>> >>>> >>>>> -----Ursprungliche Nachricht----- >>>>> Von: [email protected] >>>>> [mailto:[email protected]] Im Auftrag von Poul-Henning Kamp >>>>> Gesendet: Donnerstag, 11. Juni 2009 12:50 >>>>> An: Discussion of precise time and frequency measurement >>>>> Betreff: Re: [time-nuts] Thunderbolt stability and ambient >>>>> temperature >>>>> >>>>> >>>>> In message <e182724b9fce4b9f9e914bcc4f374...@athlon>, "Ulrich >>>>> Bangert" writes: >>>>> >>>>>>> For PLL steered devices, you want your device enclosed by a >>>>>>> thermal mass which is again enclosed by a layer of thermal >>>>>>> isolation. The goal is to filter/average all rapid (daily ?) >>>>>>> external temperature influences, only letting through such >>>>>>> slow variations (seasonal ?) which the PLL can comfortably >>>>>>> >>>>> cope with. >>>>> >>>>>> My impression with this thread is that two sligthly different things >>>>>> are being discussed here: >>>>>> >>>>>> Some posters explain how a crystal oven shall be designed as >>>>>> Poul-Henning does with his words above. Absolute correct, no doubt >>>>>> about it! >>>>>> >>>>> I'm not talking about crystal ovens, I'm talking about >>>>> timekeeping kit in general: how to filter high frequency >>>>> temperature fluctuations out, so the PLL does not have to >>>>> deal with them. >>>>> >>>>> The above advice applies to GPSDO's and Rb's and Cs's as well >>>>> as TCXOs, OCXOs and voltage references. >>>>> >>>>> Poul-Henning >>>>> >>>>> -- >>>>> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >>>>> [email protected] | TCP/IP since RFC 956 >>>>> FreeBSD committer | BSD since 4.3-tahoe >>>>> Never attribute to malice what can adequately be explained by >>>>> incompetence. >>>>> >> >> >> >> >> _______________________________________________ >> 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. >> > > > -- > Dr. Don Latham AJ7LL > Six Mile Systems LLP > 17850 Six Mile Road > POB 134 > Huson, MT, 59846 > VOX 406-626-4304 > www.lightningforensics.com > www.sixmilesystems.com > > > _______________________________________________ > 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.
