5-1/2 and 6-1/2 digits bench multimeters - Page 1
Forum section: electronics / general

author: madires
author_rank: Super Contributor
timestamp: July 01, 2012, 08:06:47 pm
content: Hi!Currently I'm looking for a bench multimeter with 5-1/2 or 6-1/2 digits and matching accuracy. The most interesting DMMs with a nice value/price ratio I found are the Tongui TH1951, Tongui TH1961 and the Picotest M3510A/M3511A. I already read an older thread about the TH1961, but would be happy to hear about any experience with the DMMs above. There's a lot of negative feedback for Rigol DMMs, so I won't consider them. Also, Fluke isn't an option since their stuff is quite overpriced in the EU and I don't support such rip-off. I prefer to buy my tools within the EU due to warranty issues.Best regardsmadires

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 01, 2012, 08:39:57 pm
content: Keep an eye out for a used HP/Agilent 34401A

author: sotos
author_rank: Frequent Contributor
timestamp: July 01, 2012, 09:56:05 pm
content: Quote from: madires on July 01, 2012, 08:06:47 pmHello I have one, and want to sell it. Its brand new in the box, I will take some pictures and sell it in EBay. If you can wait 3 – 4 days and you are still interested, I can notify you.Sotiris.

author: free_electron
author_rank: Super Contributor
timestamp: July 01, 2012, 09:59:37 pm
content: bingo. 34401 is the gold standard. That , or a keithley 2001 or 2002Agilent :34401344053441034411Keithley:20012002Don't mess around with the old hp 3456. They go cheap on ebay but are big and bulky and very old.One more thing. Don't fall for vendors that list stuff as NIST calibrated ... NIST does not perform any calibration of equipment ! you can have a nist-traceable calibration. NIST will only verify reference cells and transfer standards . Those are then used to calibrate equipment. it is NOT NIST doing the calibration !

author: Unknown
author_rank: Unknown
timestamp: July 01, 2012, 10:49:38 pm
content: Don't forget the Keithley 2000. Avoid the Keithley 2100, it was an outsourced design with limited support/documentation and some annoying firmware bugs that were never fixed as far as I know.Quote from: free_electron on July 01, 2012, 09:59:37 pmVery old or very well aged?

author: T4P
author_rank: Super Contributor
timestamp: July 02, 2012, 05:10:28 am
content: Quote from: madires on July 01, 2012, 08:06:47 pmActually Rigol ain't half bad, and as for TongHui there's a sharp possibility it's a rebranded productBut in any case if you want a good bench DMM, use those that FE mentioned, Agilent makes really good stuff

author: free_electron
author_rank: Super Contributor
timestamp: July 02, 2012, 05:14:13 am
content: amen to that. their 3458A is a thirty year old design and still the rolls-royce under the meters.It is still the machine used to calibrate the calibratorsAlthough fluke now released a new one a couple of years ago that is slightly better.one day... one day... ah, one can only dream.

author: bingo600
author_rank: Super Contributor
timestamp: July 02, 2012, 05:38:01 am
content: 34401A - Ebay : 140786285589Slovenia - Also EU/Bingo

author: Bored@Work
author_rank: Super Contributor
timestamp: July 02, 2012, 04:15:46 pm
content: A Tonhui has been shown here, and it was surprisingly well build. It looked pretty much like it was an original Tonghui design. But yes, it has no pedigree.One Rigol shown here in the past was an absolute disaster. It looked like a pre-production prototype. Another one shown her looked okish.

author: robrenz
author_rank: Super Contributor
timestamp: July 02, 2012, 05:04:25 pm
content: Hugoneous did a hour long video review of the rigol 6.5 digit.https://www.eevblog.com/forum/product-reviews-photos-and-discussion/video-review-rigol-dm3068-6-5-digit-digital-multimeter/msg125265/#msg125265He likes it. Worth taking a look at least.BTW, I love my 8846A

author: saturation
author_rank: Super Contributor
timestamp: July 02, 2012, 06:58:33 pm
content: Poor 3456a! See older discussions on eevblog for pros and cons.As alm suggests, if you're a hobbyist, the 3456a will give you the same accuracy for VDC and ohms as the 34401a but at a slower reading rate, but much more user serviceable. The VAC is fairly mundane and it has no amp range.Working uncalibrated units sell for $30-200 on eBay, versus $600-1000 for the 34401a, which is still in production. Abuse aside, the typical, if not, uncommon failure of 3456a over time is a PSU electrolytic cap, it will give error -4 on self test. Avoid the 2015Axxxxx serial numbers if you can, because the earliest run of them had defective eproms that have lost data with age [ any pic of the 2015Axxxxx series rear case will show a fan cage, which was removed in the later versions.] Fewer parts in the 3456a are unobtanium compared to the 33401a [ but you can send it back to Agilent for repairs.] If you need more than just high accuracy VDC and ohms, clearly look elsewhere. I paid $50 x 2, $100, and a calibrated one for $150, for 4 units; 3 years later one died with the -4 error and I'm in the process of replacing the cap.Quote from: alm on July 01, 2012, 10:49:38 pm

author: madires
author_rank: Super Contributor
timestamp: July 03, 2012, 10:30:21 pm
content: Hi!Thanks for the great feedback so far! I'm curious about the upcoming take-it-apart of the Rigol DM3068. Maybe I should have another look at the Rigol DMMs. The user defined sensor feature is really a great idea. Regarding Picotest someone told me that their flagship, the M3500A, is repackaged by Agilent or Fluke.Cheersmadires

author: Unknown
author_rank: Unknown
timestamp: July 04, 2012, 01:50:45 am
content: You're probably referring to the fact that both Picotest and Keithley rebadge the Array M3500A (Keithley calls it the Keithley model 2100). There have been a number of complaints about firmware issues in the Keithley 2100 that the Keithley engineers were unable to fix (probably no access to the firmware). If Keithley couldn't get the Array engineers to fix it, than I doubt the Picotest version is going to be any better.

author: slburris
author_rank: Frequent Contributor
timestamp: July 04, 2012, 09:34:55 pm
content: I have the Fluke 8502A and Fluke 8505A both were eBay finds and match each other within a few counts of the last digit. They seem to be rock solid and they seem to be at least as accurate as the voltage and resistance standards I have access to.Scott

author: free_electron
author_rank: Super Contributor
timestamp: July 04, 2012, 10:32:31 pm
content: Quote from: madires on July 03, 2012, 10:30:21 pmno way. forget that. Agilent doesn't rebadge that stuff. their ow cost designs are made by the company they absorbed a few years ago. They are all in-house designs.even the low end cheapo scopes built by rigol for them are agilent only. you will not find these under a different name. They don't play that game.i must say i am shocked beyond belief that keithley sells this under their name while it is an Array design ... Oh how deep the great have fallen ... a sad day in history indeed.

author: nctnico
author_rank: Super Contributor
timestamp: July 04, 2012, 10:45:24 pm
content: Isn't Keithley part of Tektronix these days? Anyway, what I've seen from Array is not bad at all.

author: nanofrog
author_rank: Super Contributor
timestamp: July 04, 2012, 10:55:21 pm
content: Tektronix (Danaher) now owns Keithley.Not sure what's going to happen of this though (mold Keithley into a step up from Fluke, drop Fluke from bench DMM's entirely, or something else).

author: nukie
author_rank: Frequent Contributor
timestamp: July 05, 2012, 02:27:29 am
content: Keighley 2000 is one of my most reliable multimeter. Its aged well and it hasn't drifted a single digit for pass 5 years. It's very impressive lm399. The design was no doubt influenced by the hp34401a looking at the internal hardware. Pretty annoyed and disappointed when I first learned they rebadge units.tapatalk

author: free_electron
author_rank: Super Contributor
timestamp: July 05, 2012, 03:23:52 am
content: The Danaher corporation 'borged' Tektronix , Fluke and Keithley ... and went through the product lines with a bazooka.I believe the Keithley 2000 is slightly older than the 34401 and the 2001 and 2002 were the answer to the 34401.As far as keitlheyt being influenced by Agilent. I don;t think so. These are real Keithley designs. Not only are the guts of these machines very different , they use totally different measurement principle. I the keiltey A/D is a pipelined SAR while agilent is multislope. Keithley must have had serious problems when designing their unit as the actual A/D convertor is a separate module that plugs in to the main board. They use an Actel CPLD and discrete opamps to make this thing.All these machines use LM199 reference zeners and an AD637 as true RMS convertor.Range switching, input scaling, ohms current sources are done using an in-house designed and fabbed asic for Agilent. A silicon substrate, laser trimmed hybrid makes the precision divider in Agilent. Also built in their semiconductor fabs.The keithley machines (i'm talking 2001 and 2002 .. im not very familiar with the 2000 ) build all that stuff with discrete opamps and caddock or bourns thin film alox resistors. Switching is done useing DG442 style analog muxes.The Keithley 2001 and 2002 has maybe 50 ic's to do all that work. in Agilent there's 2...The problem is temperature drift...Keithley had problems with a whole slew of 2001's due to a design flaw in the power supply. the rectifiers were built using MELF glass body 1n4001's. once in a while these would go in short , taking out half the power supply ( they have like 6 voltage all derived from one rectifier... ) , frying all the traces underneath the fat capacitors close to the rectifier.i've seen 5 or 6 with that problem. ( we had a stack of those that died ... i tried fixing em in a spare moment.. this was years ago. like 2002 or so .)They typically died when switching them on. i don't know if it was the inrush current that killed the diodes over time . fact was they went out with a sharp 'pet' sound and smoke came out. the mains fuse didn't blow... They eventually fixed this. we got new ones.Keithley made good instruments... So sad to se that they now have fallen to the point of selling a wingpangpong with their name on it..

author: T4P
author_rank: Super Contributor
timestamp: July 05, 2012, 04:24:36 am
content: Whether Array is wing-wang-pong or not ( They are from Taiwan, not China so they aren't WWP )It's still very bad for Keithley to rebrand.

author: nukie
author_rank: Frequent Contributor
timestamp: July 05, 2012, 02:05:57 pm
content: My apologies if I have supplied the wrong information. I looked inside my Keithley 2000, and to me the parts look like late design so it makes me think it is younger than HP. Also, a lot of parts(relays etc) looked like they borrowed directly from HP34401A but no doubt many of the A/D conversion is different. My oldest HP34401A is 21 years old judging by the date code and the date on the aluminium shield.

author: free_electron
author_rank: Super Contributor
timestamp: July 05, 2012, 03:38:43 pm
content: Post a pictureof the guts of the 2000.That way we can do. A teardown and circuit explanation

author: reagle
author_rank: Unknown
timestamp: July 06, 2012, 01:10:22 am
content: What about older Flukes? I am rather fond of my 8842A- cheap and very well built 5 1/2 digits. Also Fluke 45s

author: nukie
author_rank: Frequent Contributor
timestamp: July 06, 2012, 03:05:12 am
content: No problem I will start a new thread on the Keithley 2000tapatalk

author: reagle
author_rank: Unknown
timestamp: July 08, 2012, 02:13:53 am
content: Here is an ebay auction for Fluke 45:http://www.ebay.com/itm/fluke-45-multimeter-works-great-/300735942461?pt=LH_DefaultDomain_0&hash=item4605424f3dThough he only ships to US.

author: sotos
author_rank: Frequent Contributor
timestamp: August 17, 2012, 05:53:18 pm
content: PICOTEST M3510A, 6.5 digit, dual display, high performance digital multimeter.Item is for sale.If, still interested.http://www.ebay.com/itm/261084203456?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1558.l2649

author: PA4TIM
author_rank: Super Contributor
timestamp: August 17, 2012, 11:40:13 pm
content: I have a Keithley 2000 and I like it. Also a 196 anf 199. I doubed between a Fluke and agilent but the keithley had some functions the agilent had not that were important to me. The accuracy was comparable with the Fluke ( the more expensive one, end on 46 ? ) but that was allmost 400 euro more.The Keithley was calibrated nist tracable, came with certificate that named calibrators brand and serialnumber and date of nist calibration.Also an older solartron 7,5 digit.One day I hope to find an affordable 3458 ( one must have a dream)

author: mahwe
author_rank: Contributor
timestamp: September 10, 2012, 09:22:39 pm
content: First sorry for my bad english.i would like to buy a Fluke8846A or a Agilent 34410A.Does anybody use them with Labview or matlab?I know the Agilents from the university an i love them, but i like the Plot and the Histogram from the Fluke.I would like to use the DMM together with other Instruments.How good is the RS232-USB and the Lan communication in compare with the agilent ?

author: Arek_R
author_rank: Regular Contributor
timestamp: April 03, 2018, 08:55:50 pm
content: Hi folks, what do you thing about this offer:?https://www.ebay.co.uk/itm/Agilent-HP-34401A-6-5-Digit-Multimeter-2-Wire-4-Wire-KEYSIGHT/183032253806?hash=item2a9d928d6e:g:BRgAAOSwFMdaZn5D

author: mbless
author_rank: Regular Contributor
timestamp: April 05, 2018, 06:20:14 pm
content: Quote from: Arek_R on April 03, 2018, 08:55:50 pmIt looks really clean and has GPIB & serial but is too expensive for me. If that is a calibration sticker from Jan. 2009, you should have it calibrated which will run you another ~£250. That brings you up to £700, at which point I'd rather buy a new DMM.I bought a brand-new (2 month old factory calibration) 34465A for £900 last year. No GPIB, but has usb and ethernet I can connect to for automation.

author: Miti
author_rank: Super Contributor
timestamp: April 05, 2018, 11:35:04 pm
content: Nobody likes HP 3478A apparently. It is a 5.5 digits after all, I have 2 of them and I like them a lot. They're well aged, never drift. You replace carefully the battery and it is good for another 20 years.

author: nanofrog
author_rank: Super Contributor
timestamp: April 05, 2018, 11:51:23 pm
content: Quote from: Miti on April 05, 2018, 11:35:04 pmFWIW, I find they're too hard to read since the LCD display isn't backlit.

author: GreyWoolfe
author_rank: Unknown
timestamp: April 06, 2018, 02:31:08 am
content: Quote from: nanofrog on April 05, 2018, 11:51:23 pmNo biggie if you have the surface of the sun over your workbench like I do.My little Micronta 22-175A display is like that and I can see it just fine. YLMV(Your lighting may vary).

author: nanofrog
author_rank: Super Contributor
timestamp: April 06, 2018, 10:47:28 am
content: Quote from: GreyWoolfe on April 06, 2018, 02:31:08 amGood point.Since I've moved my benches to a different wall, my lighting has actually improved enough such a display would be more visible (swapped CCFL's for ~6000K LED's in the ceiling fixture). Display angle could still be a problem though. An easy fix for handhelds as they're easily repositioned. Not so sure with a bench unit (viewing angle = ?).FWIW, I'm still trying to get the lighting sorted (no room for swing arm lamps as before). Looking atinexpensive magnetic machine lightsfor sewing machines/lathes/milling machines as they'll easily attach to the bottom of my shelves as they've steel angle on the bottoms for additional support.

author: GreyWoolfe
author_rank: Unknown
timestamp: April 06, 2018, 03:31:21 pm
content: Quote from: nanofrog on April 06, 2018, 10:47:28 amI have 2, 4ft Envirolite 6 bulb 5200K LED shop fixtures over my workbench, end to end, suspended from the ceiling. Each fixture is supposed to be 10,000 lumens. Doesn't matter if they are or not, they are BRIGHT! I am completely LED in the office and I am very happy about it. Lots of light, a better quality light from the fluorescent bulbs and cheaper to run.

author: nanofrog
author_rank: Super Contributor
timestamp: April 06, 2018, 03:48:23 pm
content: Quote from: GreyWoolfe on April 06, 2018, 03:31:21 pmAre you trying to replicate a small star in there or something?I suspect I'd end up like this after sitting in that much light...

author: Arek_R
author_rank: Regular Contributor
timestamp: April 06, 2018, 09:08:11 pm
content: Quote from: mbless on April 05, 2018, 06:20:14 pmYeah it's not a good price, but well here in EU it's like that.Or maybe someone could save me with untaxed shipping in normal prices from USA to meSo we find nice deal, I purchase it to someones adress in US, send via paypal $50 for shipping + "thank you" in equivalent of 20-pack of beerBecause usually they charge automatically like $100-$300 for shipping and some ridiculous 40% tax, global shipping program in a nutshell...EDIT: Found better offer from US with normal shipping price($40):https://www.ebay.co.uk/itm/Hewlett-Packard-34401A-6-Digit-Digital-Multimeter/282912993966?hash=item41deedb2ae:g:fp4AAOSwrXdaxiORWith some luck I might be able to get it for 300GBP($400?)What do you think?

author: nanofrog
author_rank: Super Contributor
timestamp: April 06, 2018, 11:29:02 pm
content: Quote from: Arek_R on April 06, 2018, 09:08:11 pmYou might want to take a look at reshipping services (example).FWIW, other members have used such services successfully.As per the eBay unit you linked, it's a good price IMHO (add ~$100 in shipping and customs based on eBay's estimate). So I'd recommend figuring out your max bid and give it a go.

author: Arek_R
author_rank: Regular Contributor
timestamp: April 07, 2018, 12:06:18 am
content: It's $40 for shipping and $65 for import charges.I'll try $320, which will close in $425 or about 300GBP.

author: rhb
author_rank: Super Contributor
timestamp: April 07, 2018, 12:54:21 am
content: I picked up a 3478A for $109 with shipping recently. It arrived somewhat dirty, but it cleaned up really well. I can't say about the calibration but it is rock steady on any of three LM399 references. Pretty hard to beat in the "bang for the buck" department.

author: GreyWoolfe
author_rank: Unknown
timestamp: April 07, 2018, 02:02:26 am
content: Quote from: nanofrog on April 06, 2018, 03:48:23 pmFunny you mention the small star. When I turn one of them on, SWMBO asks if I am trying replicate the sun in the officeI justAs far as the guy with the cane, you can't look at these fixtures when they are on, they leave spots, not that I didn't do that when I first set them up, of course not.I also don't press the red button that says DO NOT PRESS!

author: Miti
author_rank: Super Contributor
timestamp: April 07, 2018, 02:55:33 am
content: Quote from: rhb on April 07, 2018, 12:54:21 amThey are amazing instruments with few limitations:- As mentioned before, they don't have back light - a minor inconvenience for me.- Unshrouded connectors - I think this is bigger than the back light. You'll have to cut the probes shrouds.- It only goes up to 300V - I don't remember the last time I needed to measure more than 300V though.- Doesn't have high Z mode - this is a big one in my opinion, 34401 and Fluke 884x both have it and I used it many times.Sure 34401 and Fluke are different beasts and if you need that resolution and you can afford one, go for it. I have both at work and a Fluke 8845A at home but my go to instruments are HP3478A and Fluke 179 for continuity. It just feels so right, so reliable, it's hard to describe. Fluke 8845A (and 34401 as well) is a bit annoying with its ever changing last two digits and slow buzzer so unless I really need that resolution or I need Hi Z or multiple meters, I don't feel like using it.

author: mtdoc
author_rank: Super Contributor
timestamp: April 07, 2018, 03:43:13 am
content: Quote from: Miti on April 07, 2018, 02:55:33 amNo! Don’t do this.Get a set ofProbemaster 8018S probes with retractable shrouds. They’re excellent probes that work perfectly with the excellent HP3478A.

author: nanofrog
author_rank: Super Contributor
timestamp: April 07, 2018, 08:36:07 am
content: Quote from: mtdoc on April 07, 2018, 03:43:13 amSeconded.These are excellent probes, and the retractable connectors make them usable in both new and old equipment (works with both shrouded and non-shrouded input jacks on DMM's).FWIW, you'd want the 8018S version (retractable connectors).FWIW, they also offer a 9000 modular series (9101S).

author: Miti
author_rank: Super Contributor
timestamp: April 07, 2018, 11:50:30 am
content: Interesting, thanks! I use Probemaster at work, the ones with retractable tip, but I missed that they make retractable shrouds as well.The reason why I cut them was that I had a lot of Fluke and Pomona with broken wire from too much bending, recovered from the garbage bin at work and repaired.We can't fix them due to safety concerns but for me, they are acceptable, I don't have high voltage, high energy applications.Well, the 3478A value just went up.Not to mention that we may be onto something with calibration. Check this out:https://www.eevblog.com/forum/repair/hp-3478a-how-to-readwrite-cal-sram/Soon we may be able to fine tune whatever range we want in the comfort of our basement for almost nothing... well, you'll need a transfer standard of some sort and a GPIB adapter.