Deep soil temperature stability is a bit of a myth, mainly because not many people actually measure it. I measured a beautiful 0.2C degree annual sine wave 15 metres down in limestone in Kentucky. The catch is the Gauss's Error function drop-off rate of temperature fluctuation is a very good low pass filter, so all the ambient noise of longer than a year period is not well attenuated. Secular variations, like a warm winter, a warmer than normal decade, all appear with less attenuation. 100 year functions reach 100 metres depth, and that does not count effects from percolating ground water. Admittedly a deep cellar made a good clock vault, but a thermistor, a computer fan and a 100 watt filament lamp in a wooden box can give far more accurate temperature control.
cheers, Neville Michie On 23/07/2014, at 10:17 PM, Alexander Pummer wrote: > it does need a different design, but a buried oscillator, 5 to 8 meter deep > in the garden has the best temperature stabilization, just don't turn thee > power off, but that could be done using the old Greek water-clock principle, > the spill over stabilizer. In the Bay Area [California] the soil's > temperature is around the year approximately 17C° ±0.01C° if you go further > down it will be even more constant, without any heating power and control > loop.... > 73 > KJ6UHN > Alex > On 7/22/2014 6:43 PM, Bob Camp wrote: >> Hi >> >> A lot depends on the oscillator. My fine old GR rack mount took most of 9 >> months to settle most of the way. It was still dropping in a year after that >> when I stopped watching it. Some of my T-Bolts took a week, some took a >> couple months…. >> >> Best thing you can do with any OCXO is just leave it on power. >> >> Bob >> >> On Jul 22, 2014, at 7:53 PM, paul swed <paulsw...@gmail.com> wrote: >> >>> Agree with Marks comments. >>> Regards >>> Paul >>> >>> >>> On Tue, Jul 22, 2014 at 5:25 PM, Mark Sims <hol...@hotmail.com> wrote: >>> >>>> An oscillator can take many weeks to settle in after being powered off / >>>> shipped / abused / looked at cross-eyed / etc. It typically takes a >>>> Thunderbolt a month or two to settle down after being shipped from China. >>>> _______________________________________________ >>>> 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. >> _______________________________________________ >> 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. _______________________________________________ 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.
