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| UT61E drift and recalibration |
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| stephenlm324:
I have drawn a blank on calibration of the resistance range. The voltage divider network could be replaced with a Caddock 1776-C4815 $23 from Digikey postage of arround $50, gasp. But I suspect that even this might not help. Page 9 of the ES51922 data sheet referring to the "divider ratio" mentions R6, so where is it? I had been under the impression that it was referring to the voltage divider resistors but there are only 5 of those. The only conclusion I can come to is that the divider is "on chip". I am open to suggestions. |
| M0BSW:
--- Quote from: Rick Law on November 27, 2013, 08:12:55 am --- --- Quote from: M0BSW on November 27, 2013, 07:40:42 am --- My experience with the 61E is also on resistance, I have in a box a 5.7 ohm 1% resistor, my two Alpatek's trusted meters read 5.7 dead on , however my 61e did read 5.7 now its drifted to 6.0 ohms , in a year. I would adjust it but have know ideal which pot to twiddle plus I'm not sure if 1.3 ohms is acceptable with the specs of the 61E. --- End quote --- I found part of the problem is the probe and the socket doesn't make very good contacts. I can twist the probe banana plug (as if it is a dial) and get +- 0.3ohm delta easily as I turn the plug like a dial. Cleaning the contacts helps for a while. I suspect if you clean the plugs, jiggle it, you may get 6.0 ohms back down to 5.7ohms. --- End quote --- Spot on Rick I did and it did back down to 5.7, well I never cheers Rick calm is restored. |
| notsob:
try replacing the original leads with fluke or pomona ones, the result is a huge lesson in what quality costs (the fluke leads prob cost more than half of what you paid for the 61E) |
| Monkeh:
--- Quote from: stephenlm324 on December 20, 2013, 01:55:41 am ---I have drawn a blank on calibration of the resistance range. The voltage divider network could be replaced with a Caddock 1776-C4815 $23 from Digikey postage of arround $50, gasp. But I suspect that even this might not help. Page 9 of the ES51922 data sheet referring to the "divider ratio" mentions R6, so where is it? I had been under the impression that it was referring to the voltage divider resistors but there are only 5 of those. The only conclusion I can come to is that the divider is "on chip". I am open to suggestions. --- End quote --- R7, 100R, connected to pin 22 (OR1)... It's under the display. |
| Rick Law:
--- Quote from: M0BSW on December 20, 2013, 08:36:15 pm --- --- Quote from: Rick Law on November 27, 2013, 08:12:55 am --- --- Quote from: M0BSW on November 27, 2013, 07:40:42 am --- My experience with the 61E is also on resistance, I have in a box a 5.7 ohm 1% resistor, my two Alpatek's trusted meters read 5.7 dead on , however my 61e did read 5.7 now its drifted to 6.0 ohms , in a year. I would adjust it but have know ideal which pot to twiddle plus I'm not sure if 1.3 ohms is acceptable with the specs of the 61E. --- End quote --- I found part of the problem is the probe and the socket doesn't make very good contacts. I can twist the probe banana plug (as if it is a dial) and get +- 0.3ohm delta easily as I turn the plug like a dial. Cleaning the contacts helps for a while. I suspect if you clean the plugs, jiggle it, you may get 6.0 ohms back down to 5.7ohms. --- End quote --- Spot on Rick I did and it did back down to 5.7, well I never cheers Rick calm is restored. --- End quote --- Glad that helped! |
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