Hello Time-Nuts, I recently acquired an HP 5065A rubidium oscillator (with 10811 10MHz OCXO). I think I pretty much have it running now and have been letting it cook for the last couple of weeks. I offset the C-field + and - and measured the frequency to calculate the C-field sensitivity. My unit came out to 1.96x10E-12 per dial unit, which agrees with the manual stated 2x10E-12. So, calculated the on frequency C-field value and dialed it in. Attached is a Lady Heather plot of the frequency over the last 3 days. The purple line is the 1pps plot with the vertical scale being 20ns per division. So, the unit is off about 125ns over the last 72 hours (running about 4.92x10E-13 slow). So my C-field setting is off about 1/4 of a division, but I think I'm going to leave well enough alone. The yellow line is the NTBW50AA temperature sensor, and you can clearly see when the furnace cycles. I was away for the weekend, and you can also clearly see when I came home this evening and turned up the heat. At the very end of the plot is the spike when I turned on the lights in the shop. I love using a Thunderbolt/NTBW50AA for making frequency measurements this way. I remove the OCXO, and insert the 10MHz from the DUT. Then disable disciplining so the DAC voltage doesn't try to chase the open loop oscillator. Of course the short-term performance looks worse than it actually is because of measuring against GPS, but the long-term measurements are very good. I want to log this unit at regular intervals to see what the aging looks like. Also need to do some measurements against the cesium to see what the short-term performance might be. But, I think this oscillator will be a good reference in many cases in lieu of using the cesium. Regards, Skip Withrow

On 11/08/2016 12:16 AM, Skip Withrow wrote: > Hello Time-Nuts, > > I recently acquired an HP 5065A rubidium oscillator (with 10811 10MHz > OCXO). I think I pretty much have it running now and have been letting it > cook for the last couple of weeks. I offset the C-field + and - and > measured the frequency to calculate the C-field sensitivity. My unit came > out to 1.96x10E-12 per dial unit, which agrees with the manual stated > 2x10E-12. So, calculated the on frequency C-field value and dialed it in. > > Attached is a Lady Heather plot of the frequency over the last 3 days. The > purple line is the 1pps plot with the vertical scale being 20ns per > division. So, the unit is off about 125ns over the last 72 hours (running > about 4.92x10E-13 slow). So my C-field setting is off about 1/4 of a > division, but I think I'm going to leave well enough alone. > > The yellow line is the NTBW50AA temperature sensor, and you can clearly see > when the furnace cycles. I was away for the weekend, and you can also > clearly see when I came home this evening and turned up the heat. At the > very end of the plot is the spike when I turned on the lights in the shop. > > I love using a Thunderbolt/NTBW50AA for making frequency measurements this > way. I remove the OCXO, and insert the 10MHz from the DUT. Then disable > disciplining so the DAC voltage doesn't try to chase the open loop > oscillator. Of course the short-term performance looks worse than it > actually is because of measuring against GPS, but the long-term > measurements are very good. > > I want to log this unit at regular intervals to see what the aging looks > like. Also need to do some measurements against the cesium to see what the > short-term performance might be. But, I think this oscillator will be a > good reference in many cases in lieu of using the cesium. > > Regards, > Skip Withrow > > > > _______________________________________________ > 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. > I hope you will forgive me for reducing the SNR of this forum a bit, but is that a pro-Trump message embedded in that Lady Heather plot? Furthermore, it might also be promoting electoral fraud, though ``...vote often!'' is ambiguous (maybe that's plausible deniability?) -Ruslan

Skip Wow a poor mans test setup. Kind of my speed and no HPIB or big counters etc. Like the re-use of Lady Heather. Clever. OK now to go find the soldering Iron and hack my TBolt... Maybe not today. So if you have a 5065 with 5 MHz out it needs to be doubled? With respect to the cfield. Yes its pretty sensitive down in the sub minor tick area. When I had the 5071 for testing I could never get it quite right. But nothing was actually wrong or noisy it was at the limit of reality. Regards Paul. WB8TSL On Tue, Nov 8, 2016 at 8:12 AM, Ruslan Nabioullin <rnabioullin@gmail.com> wrote: > On 11/08/2016 12:16 AM, Skip Withrow wrote: > >> Hello Time-Nuts, >> >> I recently acquired an HP 5065A rubidium oscillator (with 10811 10MHz >> OCXO). I think I pretty much have it running now and have been letting it >> cook for the last couple of weeks. I offset the C-field + and - and >> measured the frequency to calculate the C-field sensitivity. My unit came >> out to 1.96x10E-12 per dial unit, which agrees with the manual stated >> 2x10E-12. So, calculated the on frequency C-field value and dialed it in. >> >> Attached is a Lady Heather plot of the frequency over the last 3 days. >> The >> purple line is the 1pps plot with the vertical scale being 20ns per >> division. So, the unit is off about 125ns over the last 72 hours (running >> about 4.92x10E-13 slow). So my C-field setting is off about 1/4 of a >> division, but I think I'm going to leave well enough alone. >> >> The yellow line is the NTBW50AA temperature sensor, and you can clearly >> see >> when the furnace cycles. I was away for the weekend, and you can also >> clearly see when I came home this evening and turned up the heat. At the >> very end of the plot is the spike when I turned on the lights in the shop. >> >> I love using a Thunderbolt/NTBW50AA for making frequency measurements this >> way. I remove the OCXO, and insert the 10MHz from the DUT. Then disable >> disciplining so the DAC voltage doesn't try to chase the open loop >> oscillator. Of course the short-term performance looks worse than it >> actually is because of measuring against GPS, but the long-term >> measurements are very good. >> >> I want to log this unit at regular intervals to see what the aging looks >> like. Also need to do some measurements against the cesium to see what >> the >> short-term performance might be. But, I think this oscillator will be a >> good reference in many cases in lieu of using the cesium. >> >> Regards, >> Skip Withrow >> >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/m >> ailman/listinfo/time-nuts >> and follow the instructions there. >> >> > I hope you will forgive me for reducing the SNR of this forum a bit, but > is that a pro-Trump message embedded in that Lady Heather plot? > Furthermore, it might also be promoting electoral fraud, though ``...vote > often!'' is ambiguous (maybe that's plausible deniability?) > > -Ruslan > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. >