Re: [time-nuts] new clock
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.
Re: [time-nuts] new clock
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.
[time-nuts] new clock
Greetings, Started following the discussions recently and am learning a lot. Found the temperature sensor thread interesting. Measuring contact temperature (enclosure, heat sink) is a different problem than air temperature. For closing temperature control loops the absolute accuracy is often less important than things like speed of response (phase lag), both short and long term stability, and sensitivity (noise margin). Note that the NTC sensors, while having many positive attributes, are quite non-linear over an extended range. Calibration at the actual set point is necessary for absolute work. I am building the typical beginner clock project. A surplus Trimble VCO is used to clock a microprocessor. the micro has an internal 8x PLL which adds resolution in timing and simplifies the code. A GPS PPS is the reference and a DAC closes the loop. (Info if anyone interested). Instrumentation is limited. This all works ok and I am getting out old control texts to try to improve the performance but the voltage required by the VCO to maintain lock is dropping at an alarming rate - about 30 mV / week. Is this normal or do I have a lemon? What are good sources for non-lemon quartz oscillators? Thanks much in advance for any suggestions. Richard Warner ___ 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] new clock
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.
Re: [time-nuts] new clock
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.
Re: [time-nuts] new clock
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.
Re: [time-nuts] New clock
Have an extra $1,500? http://www.symmetricom.com/products/frequency-references/chip-scale-atomic-clock-csac/SA.45s-CSAC/ N0UU ___ 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.
Re: [time-nuts] New clock
On 1/19/2011 11:39 AM, lstosk...@cox.net wrote: Have an extra $1,500? http://www.symmetricom.com/products/frequency-references/chip-scale-atomic-clock-csac/SA.45s-CSAC/ N0UU Did you miss the many earlier messages on this list? They actually had a PR blurb about this on the local TV news this morning (San Francisco, Cal), with a smiling Symmetricom guy holding one for the camera. The local announcer pronounced the company name as symmetry-com. It should be symmetric-com, shouldn't it? ___ 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.
Re: [time-nuts] New clock
On 1/19/11 2:18 PM, Rex wrote: On 1/19/2011 11:39 AM, lstosk...@cox.net wrote: Have an extra $1,500? http://www.symmetricom.com/products/frequency-references/chip-scale-atomic-clock-csac/SA.45s-CSAC/ N0UU Did you miss the many earlier messages on this list? They actually had a PR blurb about this on the local TV news this morning (San Francisco, Cal), with a smiling Symmetricom guy holding one for the camera. The local announcer pronounced the company name as symmetry-com. It should be symmetric-com, shouldn't it? When I've talked to them on the phone, they've pronounced it: sih meh' trih comm (all short i or schwa sounds... no long e) Mind you, this is in California, where we pronounce cot and caught exactly the same way. ___ 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.
Re: [time-nuts] New clock
jimlux wrote: Mind you, this is in California, where we pronounce cot and caught exactly the same way. Jim, You must be hanging out in the streets again. You need to stop that. BillWB6BNQ ___ 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.
