Inside the physics cell of a Rubidium Frequency Standard

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I recently purchased three used Rubidium Frequency Standards AccuBeat AR-60A on eBay. Two of these were marked as "for spare parts", one of these was just missing the SMA connector in the front but otherwise seems to be working.
However, the physics cell of the other one does not work with either of the two control boards and is likely broken - so I opened it to have a look inside and you can join me.
Link to the paper shown in the video: tinyurl.com/42...

Опубликовано:

28 сен 2024

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Комментарии : 15

@derekkozel Год назад

Thank you for the teardown! It was very interesting to see the insides of a small model like this. It would be great to see the various control signals as the oscillator turns on and locks in.

@uwezimmermann5427 Год назад

Yes, it probably would be - however, I don't think I will disassemble my working units, and also it will be difficult to probe the unit during operation, because of the compact design.

@xtevesousa 3 года назад

Could you let me know the name of the FB group you got the hint from? thank you.

@uwezimmermann5427 3 года назад

it is a Swedish group, facebook.com/groups/1479391662380353

@xtevesousa 3 года назад

@@uwezimmermann5427 The languague puts it beyond my reach unfortunately, did you find any other info, more specifically how communicate via serial port? Thank you

@uwezimmermann5427 3 года назад

@@xtevesousa no, I haven't, but I haven't even tried or considered this for now... The two units I have are working fine as they are, and are only about 0.2 Hz apart in frequency, even though I cannot yet confirm their absolute accuracy.

@campbellmorrison8540 2 месяца назад

Extremely thoughtful and careful teardown, actually this video is more a disassembly. I love trying to find out how these sorts of devices work so I really enjoyed listening to you impart your knowledges as you progressed A1

@vishaldotgupta Год назад

very nice and detailed information. could you find what actually was wrong with this unit. to make it work, one need right temprature (MRF tx and resistors), 6.8 Ghz feild ( can be verified using feild probes and spectrum Analyser), the continuity of coil can be verified using DMM. for infrared lamp i am not sure but can be visible using from digital camera with IR Filter removed. photo sensor could be checked using DMM and or scope. i have one of these, in which lock bit is not going down. Shell gets warm so i assume MRF is okay. Rest i need to check. I may be wrong my assumptions, so please guide

@vishaldotgupta Год назад

one more thing i will like to add. when you were testing MRF321 in diode mode, it is important to check BJT in fwd , reverse mode and in between Collector and emitter. these three tests are conclusive to check good or bad devices. three test lead may be de soldered to isolate the device

@uwezimmermann5427 Год назад

Thank you for your comments - actually I have no ambition to fix this unit, since I got two working ones. I keep this one as educational material for my students.

@ghlscitel6714 2 месяца назад

Should be slightly radioactive. 87Rb is not stable. The "Helmholtz-coil" is the tuning element. With it's magnetic field the frequency of the hyperfine transistion is modulated.

@uwezimmermann5427 2 месяца назад

The 28% of 87-Rb in the tiny amount of rubidium inside the vials has a half life of 5e10 years, so its radioactivity is not an issue here...

@ogimitzev9033 Год назад

Hi Uwe, Thank you for the nice video. Do you know the Serial protocol voltage level for AR-60 (RS232, TTL 5V/3V)? Thanks

@uwezimmermann5427 Год назад

I would need to check, but I am almost convinced that it should be RS232. You should be able to test this by measuring the idle voltage on the TX-line. If it is positive then it should be either TTL 3V/5V, if it is negative it is certainly RS232.

@ogimitzev9033 Год назад

@@uwezimmermann5427 Thank you. It is 5V, but I was unable to get a response from the device following AccuBeat RS232 protocol for their nano product.