Electronics > Repair
Repair : HP 3245A precision DC/AC source
alanambrose:
Here's an analysis of the pre-calibration error on my unit. It looks like the 1V and 10V ranges can be compensated fairly easily internally with some linear adjustments. Frankly, I'm surprised that it's so linear.
The data is here FYI:
http://anagram.net/nuts/3245a/Channel%20A%20vs%20B%20pre-calibration.xlsx
Alan
TiN:
Nice. Can you share program code, I can try on mine. :)
Can toss in Kei2400 as well for comparison.
alanambrose:
>>> Nice. Can you share program code, I can try on mine.
Hi Tin,
Sure, I'll just tidy it up a bit so you don't think I'm a complete hacker :)
Having decided there was nothing of value in the existing cal - here's the post-cal results. Error is ~5-10uV on the 1V range, +-20uV on the 10V range. I ran the cal a second time and there was no improvement. Allow for minus ~1-2uV error on the 3458A (measured with a short) even though I did autocal the DCV beforehand. Only 0.1C variation over the <1h it took to do these runs.
data is here:
http://anagram.net/nuts/3245a/3245A post-calibration A vs B.xlsx
Alan
alanambrose:
>>> Nice. Can you share program code, I can try on mine.
Hey TiN,
OK alpha-quality app here:
http://anagram.net/nuts/3245A/calibration/
- together with example output. It does the performance check as in the cal manual, the calibration sequence, and another pre/post cal check working from +-1uV to +-10V. For DCV only right now - it will be easy to add DCI.
It comes up with a calibration 'headroom' number i.e. how far away on average the tests are from the specified error e.g. if the spec says max 30uV error and the actual error is 6uV then the 'headroom' is 80%. As you'll see from the example output, ~80% is actually the kind of number I'm getting.
Let me know if you find any quirks/bugs. I would be interested in seeing the output of your runs.
Alan
alanambrose:
OK more cal data - this time DCI:
This suggests to me that my box was never calibrated during its life as it was so far out, and it seems easy to pull it way into spec. Cal headroom on DCI is into the 90% i.e. on average it is coming in more than 10x better than the official spec.
Data is here if anyone cares:
http://anagram.net/nuts/3245A/calibration/3245A post-calibration A vs B.xlsx
Alan
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