Electronics > Metrology
Fluke 5440A calibration
Rax:
Hi all,
Having just repaired my 5440A, I'd like to get it up to snuff.
There seem to be a few stages to this:
* Power Supplies (3-16, p.3-7) - pretty straight forward. This unit's levels were quite off when I checked them (before the repair). The unit passes all internal tests and measured exceptionally well before its first Int Cal (in my possession)
* Square Wave Generator (3-19, p.3-9) Not quite sure what the impact of this would be. Whether it absolutely needs to be completed.
* A bunch of others I may not focus on, at least in planning stages.
* External Calibration (3-27, p.3-18) Major ticket item, of course. A couple of basic questions here is that it's not able take a specific value close to 10V (such as, for instance, the Cal Club could provide). My solution to this - which I'm not sure how feasible, so I invite input - is to dial in my 731B to 10,0000000V, as indicated by my Prema 6048 (which I trust, don't REALLY ask me why ;)) and use that for the 10V step. Still thinking through the procedure, but do I absolutely need a null detector?
- For the higher ranges, I can likely use my DP 8200's 100V output, though I don't think it'd be any improvement over just relying on the 5440A's own scaling linearity, as Dr Frank suggested on a different thread. I don't have anything for 1000V.
- For the lower ranges, I'd use by KVD to divide down the 10V from the 731B.Thanks for sharing your input.
bdunham7:
--- Quote from: Rax on September 20, 2023, 01:17:00 am ---
* External Calibration (3-27, p.3-18) Major ticket item, of course. A couple of basic questions here is that it's not able take a specific value close to 10V (such as, for instance, the Cal Club could provide).
--- End quote ---
I'd be reluctant to actually make a calibration adjustment to either of those two sources until I had a decent history on the unit and knew its behavior (stability and tempco) over some time. The 5440A is probably your most stable and accurate device by OEM specifications. It is using the same reference as the 731B but with an oven. And at this level, you start to really need a temp-controlled environment.
Are you absolutely sure about the inability to take voltages that deviate from nominal as a reference? This would seem to be a huge oversight and this ability appears as step 9 of every 5440-series manual I could find, although I'm not at my normal computer at the moment and don't have an actual 5440A service manual handy. After all, every other Fluke microcontroller operated device that has software calibration entry has this ability, even the old 8500-series DMMs.
Rax:
--- Quote from: bdunham7 on September 20, 2023, 03:08:06 am ---I'd be reluctant to actually make a calibration adjustment to either of those two sources until I had a decent history on the unit and knew its behavior (stability and tempco) over some time. The 5440A is probably your most stable and accurate device by OEM specifications. It is using the same reference as the 731B but with an oven. And at this level, you start to really need a temp-controlled environment.
--- End quote ---
Which is why the way I envisage doing this is relatively consequently (within a day or, say, a weekend; even, if possible, in immediate sequence). I think I'd be able to complete the procedure with temperature variations of less than 1C.
The 5440A is, from my observations this far, in a completely different league than what I've seen before. I think the 731B is possibly not too far, but essentially, I'd use it purely as a transfer standard. I think as such it's intended to travel, be shipped maybe, experience some temperature variations, etc., but in my case it'd experience none of that.
--- Quote from: bdunham7 on September 20, 2023, 03:08:06 am ---Are you absolutely sure about the inability to take voltages that deviate from nominal as a reference? This would seem to be a huge oversight and this ability appears as step 9 of every 5440-series manual I could find, although I'm not at my normal computer at the moment and don't have an actual 5440A service manual handy. After all, every other Fluke microcontroller operated device that has software calibration entry has this ability, even the old 8500-series DMMs.
--- End quote ---
I'm not, this is from a relatively cursory read of the SM. Currently traveling for work, so limited capacity for this, but was hoping for some input from those with experience on this unit.
But the 5440A SM I have doesn't have a step 9 at the External Calibration procedure... ?... (mind you, the 5440A SM is only available as an Artek PDF, and is definitely different than the Bs or the 5442). Only seven steps in that one. May be a difference in software?
Rax:
Here are the pages on the "External Calibration" from the 5440A SM.
bdunham7:
It's in the second sentence of step 6.c.
I think the USA Cal Club FX standard is the best possible answer for 10V, something recently transferred from that might be next-best. But on those lower ranges are your substitutes for the 752A really adequate? Personally I would only be adjusting it's calibration if I was reasonably confident I knew both how stable it was and approximately how much it was off--after comparing with multiple independent references. Your 5440A may well turn out to be the most accurate instrument of your entire lot, especially after a 30-day power on bake out.
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