Electronics > Metrology

Feasible? Convert Fluke 5440B A9 Into Stand Alone DC Standard

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denimdragon:
The title says it all. I have had this 5440B for several years and I have
attempted to repair it here and there, initially spending several days
replacing bad caps, burnt carbon resistors, burnt regulators, and even
meticously clean those damn relays 3 times (All of them  :-//). I have
revisited the calibrator at least 2 times every year, with some success,
only to have new faults appear. I was going to get rid of it 2 years ago,
but was advised against it as it is a very stable once working right, but
now, I don't have the luxury of time or space that I once had, so I need
to make use of it.

I'm in need of a very stable voltage reference, and since the 5440B
is very stable and has two aged SZA263s on board with a heater,
I am wondering how difficult it would be to use the A9 board as
a stand alone 13.2 volt reference, possibly trimming it later to 10V and
maybe 1.018 or 2.500 volts. But the 10V is of course the main target.
The other voltages would just be an added luxury.

I would like to do as little as possible to the original A9 board in order
to achieve this. I basically want to power the SZA263s, the Heater and
any absolute necessary supporting circuitry. I can machine a costume
enclosure for the complete board with power and terminal connections
on the outside and some type of temperature monitoring.

Does this sound moderately simple to do? Also, does it seem like
a good idea? It would save me quite a bit of money as I will still need
to purchase a second commercial 10V reference (732A/B).

I'm open to suggestions and comments. TIA

bdunham7:
You'd probably be better off selling the complete but not working 5440B and getting something else like a 732A.  Dividing down your 13.2V to a stable 10V is not so easy either if you want a low output impedance.  And then you'd have to calibrate and characterize it anyway. 

You also might be overestimating your need for super-precision 10V references.  An environmental chamber, the ability to accurately measure temperature and humidity and a multi-channel logging method that has low thermal voltages are all things you probably should look at first.

Rax:

--- Quote from: bdunham7 on March 01, 2024, 09:06:40 pm ---You'd probably be better off selling the complete but not working 5440B and getting something else like a 732A.  Dividing down your 13.2V to a stable 10V is not so easy either if you want a low output impedance.  And then you'd have to calibrate and characterize it anyway. 

--- End quote ---

I agree with bdunham7. The 5440 series are well appreciated and sell very well (aside from their extreme size and weight and the associated hardship for the seller). But, with a bit of patience and persistence, you may be able to grab a 732 with hopefully minor issues with the money you'd get for a non-functional 5440.

While running the A9 PCA independently of the main unit may not be impossible, I don't think it will turn out to be trivial; how much effort are you willing to put into this graft is up to you, but I'd think it may not be the most optimal path forward to achieving your stated goals.

denimdragon:
Ok. So I'm sold that it's not the most efficient way to move forward,
but now I'm thinking about keeping it after dropping of my 34401A
and Fluke 5450A to get calibrated today. I had a conversation with
the metrologist there and he told me that I should keep it and just
buy a 732A/B. He said that the 5440 and 5442 are really super
solid boxes. He also said he would calibrate it for a reasonable
price once I fixed it. It would be a bit because he had just sent
off his 732s. That gave me new hope so I guess I will start
Back on the repair path. Maybe I can get back on it at the
End of the month.

bdunham7:

--- Quote from: denimdragon on March 05, 2024, 02:25:06 am ---I'm thinking about keeping it after dropping of my 34401A
and Fluke 5450A to get calibrated today.

--- End quote ---


Two questions:  What age/firmware is your 34401A and are you getting data with the calibration?  If so and if it is a good lab, I'd like to see the data if you're willing to post it.

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