Fluke 8845A 6.5 Digit Precision Bench Meter vs. ??? - Page 1
Forum section: electronics / testgear

author: Unknown
author_rank: Unknown
timestamp: July 10, 2013, 12:12:26 am
content: Fluke 8845A 6.5 Digit Precision Bench Meter vs.the UNI-T version is a joke... compared to the same brand hand held units.vs. Agilent, what else?

author: EEVblog
author_rank: Unknown
timestamp: July 10, 2013, 12:14:53 am
content: Agilent 34461A, Rigol, and Keithley 2000 are the main rivals.

author: ElektroQuark
author_rank: Unknown
timestamp: July 10, 2013, 08:58:25 am
content: Agilent 34401A, Agilent 34410A.

author: Unknown
author_rank: Unknown
timestamp: July 11, 2013, 12:16:37 am
content: Fluke 8865ACan measure capacitors as low or as high as the Rigol DM3068.?Or is it just another overpriced piece of s@&€) ?I'm very impressed by the video review found on the web...The main actractive of Fluke for me is that all Multimeters exept the 15B are Tempereture Stable.With my Uni-T Ut601 i can measure 20pF, flawless, "21.1"15pF "14.4, 14.6" 3 different capacitors.10pF "9.2, 9.4, 9.7" 4 measured.1pF "1.3, 1.1, 1.2" 3 tested.47pF "44.4" 1 tested.Dont't know whats the big deal, all reviews i seen, claim that pF is soo small to measure, the air blablabla, and they are amazed how dificult is to measure capacitors so small...I'm happy with my Uni-T, but tired of purchasing 9v batteries, Duracell is very hard to find here, and is the only that last long.I would be very bummed if i spend $1000usd, and can't measure as good as the Ut601,Sometimes i wish i had an extra digit in the Ut70A,But love the 2mH - 20H.

author: ddavidebor
author_rank: Super Contributor
timestamp: July 11, 2013, 12:20:21 am
content: Read the specs...

author: Unknown
author_rank: Unknown
timestamp: July 11, 2013, 12:26:45 am
content: Quote from: ddavidebor on July 11, 2013, 12:20:21 amAccording to eevblog, Dave Agilent 34461A review "they are the same, in this range" or something like that, so why bother?Have you found something different?http://www.uni-trend.com/ut601.htmlCapacitance 200pF/2nF/20nF/200nF/2µF/20µF/200µF/2mF/20mF (0.5%+10)But looking actual measurements, Uni-T looks more accurate.>F.F.>> 39:00

author: EEVblog
author_rank: Unknown
timestamp: July 11, 2013, 12:41:29 am
content: If you want to measure capacitors properly, get a proper LCR meter, not a bench multimeter.

author: Unknown
author_rank: Unknown
timestamp: July 11, 2013, 01:00:37 am
content: Quote from: EEVblog on July 11, 2013, 12:41:29 amI guess i forget Multi meters are no UniMeter jajajajaaj

author: free_electron
author_rank: Super Contributor
timestamp: July 11, 2013, 01:10:14 am
content: Quote from: EEVblog on July 11, 2013, 12:41:29 amsecond that.and by proper LCR meter we mean a machine that uses 4 point measuring and can compensate its testleads ,and has multiple testfrequencies and possible DC bias control.

author: Kryan9
author_rank: Contributor
timestamp: July 11, 2013, 04:44:31 am
content: Curious, how exactly does an LCR meter compensate it's test leads, as doesn't the method of lead attachment to the DUT affect stray capacitances and inductances? Like, the way you attach the leads together to compensate or something for nulling is different than how they would be attached to the capacitor/inductor, right?

author: plesa
author_rank: Frequent Contributor
timestamp: July 11, 2013, 07:35:51 am
content: On good LRC with 4 point measurement meter you need to enter the lenght of the test lead and compensate open and short circuit leads.This compensation you can perform for used frequency or it will measure whole LRC frequency range in steps, walues are interpolated.The open correction compensates for any stray admittances (G, B) that may exist within the interval from the calibration plane, which is determined by the selected cable length, to the DUT connecting points.The short correction compensates for any residual impedances (R,X) that may exist within the interval from the calibration plane, which is determined by the selected cable length, to the DUT connecting points.I will recomended the Agilent 34411A, it is use the same Truevolt technology, has basic capacitance measurement and the features of the 34461A ae available throught SW on PC.But it depends on your application, for some basic measurement on the bench it is overkill.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: July 11, 2013, 09:03:33 am
content: Is there a good reason why they don't put LCR features in a 5.5 or 6.5 bench meter?I mean it probably adds max. 150Euro since most is already there. So +15% price to have aMultimeter.

author: Unknown
author_rank: Unknown
timestamp: July 11, 2013, 01:26:36 pm
content: LCR would require generating AC signals and measuring more than just the magnitude of the voltage. You could put them in the same box, like the Keithley DMM + signal generator (THD meter) combination, but at best it would save some bench space. A bench class LCR meter would add more than €150, do you really think the thousands of dollars you pay for an Agilent bench LCR meter only goes towards the power supply, display and front panel? They're not going to put a Uni-T-level LCR meter together in the same box as an Agilent 34461A.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: July 11, 2013, 02:59:45 pm
content: Quote from: alm on July 11, 2013, 01:26:36 pmR is always there, some have C (simple load curve measurement), and L is always absent.So I do not think mixing 'level' is their issue.Yes, they need to add an AC source (5 fixed frequencies) but that can't really be such a big deal?

author: Unknown
author_rank: Unknown
timestamp: July 11, 2013, 03:32:00 pm
content: LCR meters can measure the resistance using an AC signal (eg. ESR for a cap), this is a different measurement than DC resistance (which is close to infinite for a good cap). I'm not aware of any DMM that does this. Capacitance is also measured using a completely different technique by DMMs (charge/discharge rate using constant DC current/voltage, which is why they're easily confused by leaky caps or parallel/series resistance). This is why people recommend a real LCR meter for testing caps over a DMM.Go on the Agilent website and look up prices for bench LCR meters. Compare this to DMM prices + the supposedly €150 of parts that it would add to a DMM.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: July 11, 2013, 04:15:57 pm
content: Quote from: alm on July 11, 2013, 03:32:00 pmBut those expensive ones have a variable frequency (and some a very high BW) not a few fixed frequencies up to 100Khz, hence the price. All those DMM can handle 100kHz AC fine.Measuring the phase can't be hard either since they make the AC signal.

author: Unknown
author_rank: Unknown
timestamp: July 11, 2013, 06:03:36 pm
content: The Agilent 4263B has six fixed frequencies up to 100 kHz and has a list price of $2700. Well over twice the list price of a 34461A.

author: ddavidebor
author_rank: Super Contributor
timestamp: July 11, 2013, 06:40:09 pm
content: Lcr meter are expensive, the only way to do them "cheap" is do an ASIC

author: KedasProbe
author_rank: Frequent Contributor
timestamp: July 11, 2013, 07:49:14 pm
content: Quote from: alm on July 11, 2013, 06:03:36 pmThen don't buy that oneI don't know why this old one cost that much. Maybe tolerance...But a lot of cheaper ones exist, I would be fine with stripped down functionality:http://www.bkprecision.com/products/component-testers.html#!/lcr-metersThe functionality of the 879B would be fine for a desktop multimeter, otherwise they wouldn't sell that many of their LCR-meters.

author: Unknown
author_rank: Unknown
timestamp: July 12, 2013, 09:37:54 am
content: They're not going to put an inferior instrument in the same box as a 6.5 digit DMM.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: July 12, 2013, 11:26:52 am
content: Quote from: alm on July 12, 2013, 09:37:54 amMaybe, for now you are right but they did already put the inferior capacitance in there. I guess if they start doing LCR the first one to do it will be Rigol. But from my point of view they can wait 10 years until I need/want a new DMM(I ordered a DM3068 a few days ago)