3 ms·

CuriousMarc made a video last week where he uses a vintage HP 5061A atomic clock and explains how it works. It's interesting to see that atomic clocks aren't ju

by kens 7y ago

CuriousMarc made a video last week where he uses a vintage HP 5061A atomic clock and explains how it works. It's interesting to see that atomic clocks aren't just some giant laboratory thing, but a product you could buy, even in the 1960s. https://www.youtube.com/watch?v=eOti3kKWX-c https://www.youtube.com/watch?v=eOti3kKWX-c

tyingq 7y ago
CDW has a Cesium reference clock for $92k. https://m.cdw.com/product/microsemi-5071a-high-performance-tube-cesium-clock-with-48-vdc-psu/5654336?enkwrd=Cesium https://m.cdw.com/product/microsemi-5071a-high-performance-t... Pretty similar form factor.
- vibrolax 7y ago
  I believe this is the direct successor to the HP 5061A. HP spun off Agilent, who sold the time/frequency product division to Symmetricom, who was then acquired by Microsemi. It seems that the inflation-adjusted price of the Microsemi 5071A is about the same as the ~1970 catalog price of the HP 5061.
michaelt 7y ago
You can buy a used rubidium frequency standard on ebay [1] for less than $200. Of course, it turns out there aren't that many home applications for an atomic clock, other than collecting precision metrology equipment. And if you're running a data centre and want higher precision than NTP, chances are you'll choose a PTP grandmaster clock at the high end, or a GPS receiver with a 1PPS output at the low end, in rather than buying second-hand parts from ebay. [1] https://www.ebay.com/sch/i.html?_nkw=rubidium https://www.ebay.com/sch/i.html?_nkw=rubidium
- segfaultbuserr 7y ago
  > Of course, it turns out there aren't that many home applications for an atomic clock For all the people who have a rubidium standard at home, 70% are using it for electronic lab, amateur radio, or NTP at home. But the remaining 30% is another large userbase too - audiophiles. Many audiophiles claim jitter and phase noise in the clock signal significantly affects audio quality, and the most extreme audiophiles use a lab grade frequency standard, rubidium or better, and feed it to all their Hi-Fi gears. P.S: Given all the factors that affect audio quality, is the phase noise from a PLL synthesizer of reasonable quality really a major factor? Even if it is, does a rubidium standard really have any benefit beyond diminishing return over a crystal oven? Well, of course, these are the questions that are never answered by audiophiles. > You can buy a used rubidium frequency standard on ebay There is a continuous source of used rubidium standard coming from retired telecommunication and lab equipment, they are the cheapest atomic standard available. The catch is that the rubidium inside the discharge lamp will eventually get depleted during operation, usually within 10 years, once its life ends, it's useless and needs to be rebuilt completely by the manufacturer. So read the manufacturing date if you are going to power it 7x24. The real expensive ones are the Cesium Standard, such as the HP 5061A. Recently, the Hydrogen Standard also saw some uses.
  - JackMcMack 7y ago
    The rubidium does not deplete (it's a closed system), but does settle on the glass. Supposedly you can heat the glass to turn all the rubidium into gas again, giving you theoretically infinite lifetime. I picked up a used PRS-10 on ebay for $250. It's a small but great oscillator, still made today. The manufacturer SRS claims 20 years lifetime, and mine has had 13 years of runtime, so I should be able to get 7 years out of it hopefully. The 11W1 DSub connector they used on the other hand is stupidly expensive. Cesium oscillators on the other hand do deplete their cesium (by design), as mentioned by CuriousMarc in the video. The tube in his unit was probably replaced at least twice, at a cost of >80k. The high performance tubes fare even worse because they "burn" through their cesium at a 3x rate. The 5071 successor by HP-Agilent-Symmetricom-Microsemi is the most frequently used COTS clock that contributes to UTC.
    - segfaultbuserr 7y ago
      > Supposedly you can heat the glass to turn all the rubidium into gas again, giving you theoretically infinite lifetime. Thanks for the tip, that's interesting. I never know that they can be renewed in this way. > Cesium oscillators on the other hand do deplete their cesium (by design), as mentioned by CuriousMarc in the video. The tube in his unit was probably replaced at least twice, at a cost of >80k. Sad story. Recently I was browsing a web store that sells decommissioned U.S. military equipment. I was here to search for some cheap RF power meters, and I was surprised to see a HP 5071 in the listing. The vendor noted that he knew nothing about the equipment and information was welcomed. For a moment, I was thinking about sending him a service manual from the HP archive, before I realized it was simply impossible to get it up and running again without replacing the tube :( > The 5071 successor by HP-Agilent-Symmetricom-Microsemi Aha, the old Hewlett-Packard was truly a unique company. Its electronic technology has at least three separate chains of succession. Test Equipment: HP-Agilent-Keysight Semiconductor: HP-Agilent-Avago-Broadcom (Broadcom ended production of most HP parts, so now it's mostly dead, RIP...) Frequency Standard: HP-Agilent-Symmetricom-Microsemi
      - CamperBob2 7y ago
bobbiechen 7y ago
Yeah I had always thought they would be incredibly expensive. The Spanner paper (which is how I ended up at the posted link) contains this amusing line - An atomic clock is not that expensive: the cost of an Armageddon master is of the same order as that of a GPS master http://static.googleusercontent.com/media/research.google.com/en//archive/spanner-osdi2012.pdf http://static.googleusercontent.com/media/research.google.co...

by kens 7y ago

tyingq 7y ago

CDW has a Cesium reference clock for $92k. https://m.cdw.com/product/microsemi-5071a-high-performance-tube-cesium-clock-with-48-vdc-psu/5654336?enkwrd=Cesium https://m.cdw.com/product/microsemi-5071a-high-performance-t... Pretty similar form factor.

vibrolax 7y ago
I believe this is the direct successor to the HP 5061A. HP spun off Agilent, who sold the time/frequency product division to Symmetricom, who was then acquired by Microsemi. It seems that the inflation-adjusted price of the Microsemi 5071A is about the same as the ~1970 catalog price of the HP 5061.

michaelt 7y ago

You can buy a used rubidium frequency standard on ebay [1] for less than $200. Of course, it turns out there aren't that many home applications for an atomic clock, other than collecting precision metrology equipment. And if you're running a data centre and want higher precision than NTP, chances are you'll choose a PTP grandmaster clock at the high end, or a GPS receiver with a 1PPS output at the low end, in rather than buying second-hand parts from ebay. [1] https://www.ebay.com/sch/i.html?_nkw=rubidium https://www.ebay.com/sch/i.html?_nkw=rubidium

segfaultbuserr 7y ago
> Of course, it turns out there aren't that many home applications for an atomic clock For all the people who have a rubidium standard at home, 70% are using it for electronic lab, amateur radio, or NTP at home. But the remaining 30% is another large userbase too - audiophiles. Many audiophiles claim jitter and phase noise in the clock signal significantly affects audio quality, and the most extreme audiophiles use a lab grade frequency standard, rubidium or better, and feed it to all their Hi-Fi gears. P.S: Given all the factors that affect audio quality, is the phase noise from a PLL synthesizer of reasonable quality really a major factor? Even if it is, does a rubidium standard really have any benefit beyond diminishing return over a crystal oven? Well, of course, these are the questions that are never answered by audiophiles. > You can buy a used rubidium frequency standard on ebay There is a continuous source of used rubidium standard coming from retired telecommunication and lab equipment, they are the cheapest atomic standard available. The catch is that the rubidium inside the discharge lamp will eventually get depleted during operation, usually within 10 years, once its life ends, it's useless and needs to be rebuilt completely by the manufacturer. So read the manufacturing date if you are going to power it 7x24. The real expensive ones are the Cesium Standard, such as the HP 5061A. Recently, the Hydrogen Standard also saw some uses.
- JackMcMack 7y ago
  The rubidium does not deplete (it's a closed system), but does settle on the glass. Supposedly you can heat the glass to turn all the rubidium into gas again, giving you theoretically infinite lifetime. I picked up a used PRS-10 on ebay for $250. It's a small but great oscillator, still made today. The manufacturer SRS claims 20 years lifetime, and mine has had 13 years of runtime, so I should be able to get 7 years out of it hopefully. The 11W1 DSub connector they used on the other hand is stupidly expensive. Cesium oscillators on the other hand do deplete their cesium (by design), as mentioned by CuriousMarc in the video. The tube in his unit was probably replaced at least twice, at a cost of >80k. The high performance tubes fare even worse because they "burn" through their cesium at a 3x rate. The 5071 successor by HP-Agilent-Symmetricom-Microsemi is the most frequently used COTS clock that contributes to UTC.
  - segfaultbuserr 7y ago
    > Supposedly you can heat the glass to turn all the rubidium into gas again, giving you theoretically infinite lifetime. Thanks for the tip, that's interesting. I never know that they can be renewed in this way. > Cesium oscillators on the other hand do deplete their cesium (by design), as mentioned by CuriousMarc in the video. The tube in his unit was probably replaced at least twice, at a cost of >80k. Sad story. Recently I was browsing a web store that sells decommissioned U.S. military equipment. I was here to search for some cheap RF power meters, and I was surprised to see a HP 5071 in the listing. The vendor noted that he knew nothing about the equipment and information was welcomed. For a moment, I was thinking about sending him a service manual from the HP archive, before I realized it was simply impossible to get it up and running again without replacing the tube :( > The 5071 successor by HP-Agilent-Symmetricom-Microsemi Aha, the old Hewlett-Packard was truly a unique company. Its electronic technology has at least three separate chains of succession. Test Equipment: HP-Agilent-Keysight Semiconductor: HP-Agilent-Avago-Broadcom (Broadcom ended production of most HP parts, so now it's mostly dead, RIP...) Frequency Standard: HP-Agilent-Symmetricom-Microsemi
    - CamperBob2 7y ago

bobbiechen 7y ago

Yeah I had always thought they would be incredibly expensive. The Spanner paper (which is how I ended up at the posted link) contains this amusing line - An atomic clock is not that expensive: the cost of an Armageddon master is of the same order as that of a GPS master http://static.googleusercontent.com/media/research.google.com/en//archive/spanner-osdi2012.pdf http://static.googleusercontent.com/media/research.google.co...