Specications are for 6 ½ digits and two hours warm up - Page 1
Forum section: electronics / general

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: November 16, 2011, 11:30:33 pm
content: An simple question, about your own habits when using your 6 ½ digits bench type multimeter.I found in the specifications of an such 6 ½ digits meter that needs two hours warm up time,do you follow the book ?

author: Wartex
author_rank: Frequent Contributor
timestamp: November 17, 2011, 12:14:25 am
content: Afaik 8846a needs 30 minutes. It also depends on ambient temp.

author: nukie
author_rank: Frequent Contributor
timestamp: November 17, 2011, 12:21:49 am
content: If you have a low drift precision voltage reference, you can measure the warm up time vs voltage accuracy. Depending on the ambient temperature, my Keithley 2000 takes less than 10 minutes to stabilize at 23c, roughly the same as my HP34401A. This is due to the heating of the voltage reference and both models uses the same part.I find it's usually the last two digits that are slightly off by 10 to 20. The first 4 digits are usually usable when it's first powered up. My equipment are very old not sure about new stuff.

author: robrenz
author_rank: Super Contributor
timestamp: November 17, 2011, 03:06:21 am
content: From my 8846A manual; "1 hour to full uncertainty specifications"but on trend plot from turn-on it is stable in about 40 mins

author: Lawsen
author_rank: Frequent Contributor
timestamp: November 17, 2011, 04:51:28 am
content: The HP-34401A or present brand Agilent 34401A needs 1 hour to warm up for accurate measurements, but I do not have any other 6 or more digits multimeters to compare with. I do not know what I am talking about. I have an 6.5 digits multimeter and I leave it on for 15 to 30 minutes, before making a measurement and leave it on all day, until I am finished breadboarding or discrete soldering. I usually use the Fluke multimeters, which are 3.5 to 4.5 digits at most. I have a classic, the Philips PM2505 and 2518. My most oddest multimeter is the solar powered pocket sized multimeter with a self case. The Fluke 12 finally broke and I would like to trade it in at Fluke for something else. The key pad kept being non responsive for the last five years and constantly needing dis-assembly and cleaning. I would like to get the "brick," the Agilent handheld, but the economy is too slump for more instruments. The Agilent repair rate for bench multimeters are higher than Agilent DSOX oscilloscopes. Agilent oscilloscopes have a lower repair price than Agilent multimeters as listed on their Agilent web site. I do not know why? I think the lower repair rate is to have trust in Agilent oscilloscopes and increase sales to compete with low priced Rigol and Atten brands.

author: ejeffrey
author_rank: Super Contributor
timestamp: November 17, 2011, 11:01:44 am
content: 95% of the time when using my bench meter I don't care about anything beyond 4.5 digits. I use the bench meter for its functions like computer control and 4-wire ohms, or because I need a line powered instrument for long term logging. Even when I want the last digit, I generally care about resolution more than accuracy. In the rare case where I need absolute accuracy or low drift over an extended measurement I obviously let it warm up.

author: amspire
author_rank: Super Contributor
timestamp: November 17, 2011, 11:39:13 am
content: I have two Japanese Advantest R6871E-DC 7 1/2 digit multimeters. It is good for 0.01% at turn on, but for accuracy, I would run them for at least an hour.

author: Neilm
author_rank: Super Contributor
timestamp: November 17, 2011, 06:42:43 pm
content: Of course - if you want to ensure precision you would not turn it off. This is usually the practice in calibration labs who want to start work straight away. Also, some very high precision equipment might require more than 1 hour to meet uncertainty specifications. The longest I have seen was 12 hours.Neil