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looking for HP3456A (6.5 DMM) calibration service in Italy or continental Europe
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gmac34:
I recently got a HP 3456A bench meter to repair, unfortunately fresh capacitors only cured half of its problems and it turns out I need to replace one of the fine-line resistor networks.
So it will definitely need to be calibrated.
I'm looking for recommendation on "hobbyist friendly" cal labs in Italy, I do not need traceability, just to get it sorted, and I'm on a student budget...
I would preferably bring the item in person, so driving distance from Bologna would be best, but recommendations In Europe are also welcome.
Thanks
Grazie
alm:
Do you need just calibration (a report of how much it is off) or also adjustment (twiddle trimmers until it reads all zero?). The latter is a manual adjustment, so cal labs will hate it and likely charge extra compared to more modern meters like the HP 34401A where they just press a button and the whole thing gets adjusted via computer control.

If you have another 6.5 digit or better DMM or know someone who does, and can improvise sources that are sufficiently stable short term, then I would adjust the 3456A as well as possible to the other meter, and then send it out for calibration without adjustment. DCV and resistance are relatively easy. ACV is much harder to generate all the voltages and frequencies it wants. Depending on what functions are affected by that resistor network, you may not have to adjust everything.
Vgkid:
If the U200 resistor network is replaced , then all ranges(voltage/resistance) will need to be fully calibrated. That will even go down to selecting the proper select on test link resistors  :scared: . I think it would be better to use another working 6.5dig meter.
gmac34:
I assumed it would need a full adjustment but the manual is not too clear on what happens after replacing U200. There are mentions of what to adjust if the other fineline (U500) is replaced (that one is matched to the voltage Reference Assembly), and it that case there are a bunch ion jumpers to move around, but I cannot find a procedure to replace U200.
On the manual I find:
"Thin-film resistors (U200 fineline resistor package) with .010% tolerance are used in the feedback paths for the gains of 100, 10, and 2. Gain of 2 is used for Ohms measurements only."
Gain of 100 and 10 are used in all ranges apart from 10V and 1000V

To do a DIY adjustment I have a 3245A, that would cover most voltages needed for the adjustment, apart form 100v dc.
For resistance I don't have much that is stable, maybe I can use the faulty U200...
But I only have a keithley 2000 as possible reference.

Off course the alternative is to keep the meter as is and accept that it cannot measure 100V and 1000V (it's the 100:1 voltage divider in U200 that seems faulty)
NoisyBoy:
Unfortunately, I cannot help you with your original question of a cal lab recommendation in Italy.  So hopefully someone local or in the EU can help.

I see the direction has moved towards a self-cal, it all depends on what you are using the DMM for, if you get it for the purpose of doing accurate 6.5 digit measurements, then any home cal or using another DMM as a transfer standard is not going to be good enough for such meter.  Challenge being the difficulty in having the stable sources at various test points that you need, in addition to a transfer standard with recent calibration.  You really need a calibrator for such work. 

However, if accuracy is not needed, or you are just having the 3456A as a TE collection, then a self-cal may be adequate so you don't have to ship the vintage equipment around. 

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