Electronics > Repair
3458A
drhex:
@Frank: I did have a nice basement lab when I was still in Germany, incl a 3458A in really nice nick, but sold everything when moving to UK - here, I don't have meaningful temp control sadly. Will measure and document.
drhex:
First three days:
Day Date Time TEMP? CAL? 72 PPM rel day 1 Av drift Drift day by day
1 14/12/2024 9:00:00 PM 38.35 1.000859540
2 15/12/2024 4:05:00 AM 38.1 1.000859590 1 0.049957060 0.02498 -0.049957060
3 16/12/2024 11:00:00 PM 37.6 1.000859560 1 0.019982824 0.00666 0.029974234
So much better than spec so far (.43 ppm/day) even in a non temperature controlled environment, 3458A has been running continously.
Voltage at rest fluctuates between -0.71 to -0.55 µV which seems fine. Open input still goes up to about 11V then changes range which drops it down to about 7V again. This is with a shorted shielded cable, nothing fancy.
Outside of the instrument looks s***, have ordered parts from Keysight. Also have caps etc here to get the power supplies sorted.
Seems to me I made a decent buy?
And no, it isn't warped, just a pic from the auction...
drhex:
So given my temperature is all over the place is it even worthwhile continuing to measure day by day change? I assume you can't cancel TEMP changes out somehow?
1 14/12/2024 9:00:00 PM 38.35 1.00085954
2 15/12/2024 4:05:00 AM 38.10 1.00085959 1 0.049957060 0.02498 -0.049957060
3 16/12/2024 11:00:00 PM 37.60 1.00085956 1 0.019982824 0.00666 0.029974234
4 17/12/2024 9:50:00 PM 37.85 1.00085942 1 -0.119896944 0.02997 0.139879765
5 18/12/2024 7:54:00 PM 38.45 1.00085932 1 -0.219811064 0.04396 0.099914132
6 19/12/2024 12:00:00 AM 37.45 1.00085914 1 -0.399656479 0.06661 0.179845455
Dr. Frank:
--- Quote from: drhex on December 19, 2024, 06:58:55 pm ---So given my temperature is all over the place is it even worthwhile continuing to measure day by day change? I assume you can't cancel TEMP changes out somehow?
1 14/12/2024 9:00:00 PM 38.35 1.00085954
2 15/12/2024 4:05:00 AM 38.10 1.00085959 1 0.049957060 0.02498 -0.049957060
3 16/12/2024 11:00:00 PM 37.60 1.00085956 1 0.019982824 0.00666 0.029974234
4 17/12/2024 9:50:00 PM 37.85 1.00085942 1 -0.119896944 0.02997 0.139879765
5 18/12/2024 7:54:00 PM 38.45 1.00085932 1 -0.219811064 0.04396 0.099914132
6 19/12/2024 12:00:00 AM 37.45 1.00085914 1 -0.399656479 0.06661 0.179845455
--- End quote ---
As said, you can cancel TEMP variations by using a stable environment, or you can determine the T.C. of U180 and subtract this effect from the CAL? 72 parameter, hopefully chosing the correct sign. I guess, latter is automatically done by Ians program.
Frank
Kleinstein:
--- Quote from: drhex on December 19, 2024, 06:58:55 pm ---So given my temperature is all over the place is it even worthwhile continuing to measure day by day change? I assume you can't cancel TEMP changes out somehow?
--- End quote ---
To a certain degree one can correct the temperature effect. With data for a longer time window the individual measurements also get less critical.
After a long time not using the meter, there and be some additional drift anyway.
So far the drift data look good, though still a bit short to be really sure. The limit should be seen more as 3 ppm per week instead of 0.43 ppm per day.
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