Fluke 8845A Calibration with a known reference - Page 1
Forum section: electronics / general

author: rplabs
author_rank: Contributor
timestamp: October 12, 2025, 09:41:46 am
content: Hello,I bought an 8845A that was not calibrated in a very long time.I am mainly interested in the DC voltage measurements and I would like to have the 10VDC range correctly calibrated.I bought a 4W short on eBay which seems good and I already made the calibration for Open and Short for the Resistance/ACV/DCV.After Zero calibration it seems the 8845A is still reading low compared to my other 2 meters 34401A.Now the question is how can I calibrate the 10VDC range using the 731B that was last time calibrated with a 3458A and both 34401A match the 731B in 4-5ppm.8845A is showing 70 to 150ppm difference when measuring the 10VDC on the 731B.In the Fluke 8845A Programming Manual there is a command to only run one step of the calibration based on a known reference.Example: CAL:STEP 5,[Reference Value]But there are no other details and this command seems to not be covered in the calibration manual.Another issue is that the 8845A/8846A calibration manual from January 2007 Rev.1 seems to have the tables wrong.Correct step tables can be found in the Supplement Issue 5 from 10/2009.During the Zero calibration I compared the step numbers and they match the ones in the Supplement Issue 5.According to this table I need step 86 GVDC +10VDC and step 87 GVDC -10VDCSo the commands should look like this:CAL:STEP 86,9.9999701CAL:STEP 87,-9.9999701Did anyone try to calibrate their 8845A/8846A using a know reference?Can anyone confirm these commands?Thanks!

author: Skoomsday
author_rank: Newbie
timestamp: October 18, 2025 04:03:18 pm
content: You'll need more than a 731B to fully calibrate it, when it is put into calibration mode it needs to go through a set sequence of shorts. opens, volts and current inputs, resistance/capacitance inputs to fully do it. We use a 5730A, 8508A, and a 5522A to cover everything required to do it. The adjustment program came form Fluke for it as well that we run in MET/CAL.If you go into the calibration manual (not the programming manual) it details how you can either do the calibration procedure manually through the front panel, or by using a remote interface, and the chart for all the test points you need to do in order. Then you can determine if you can cover all the points required.

author: rplabs
author_rank: Contributor
timestamp: October 18, 2025 08:11:45 pm
content: I used the calibration manual and you can calibrate individual steps. I already did the open and short for ACV/DCV/resistance. Now I am interested to calibrate a single step for +/-10VDC with a known reference because my reference is not exactly 10.0VDC and it is a little bit lower. It looks like it is possible to do it and there is a command for that but not clear how to use it... I am not interested in calibrating the other ranges, only this one.Anyway, yesterday I ran more tests on the 8845A and I compared it with my 34401A and it seems it is drifting a lot. So maybe it has other issue and calibration will not fix it. I need to open it and check all caps or if there is any issue on the analog part of the multimeter or the reference itself.

author: aronake
author_rank: Frequent Contributor
timestamp: «Reply #3 on:Todayat 06:30:25 am »
content: I just posted in code on using 5700a to calibrate a 8845a. Not exactly what you are looking for, but you may be able to get some hints on how separate ranges can be calibrated.https://www.eevblog.com/forum/metrology/python-etc-code-for-fluke-5700a-control-and-calibration-of-different