Second DMM ? - Page 1
Forum section: electronics / testgear

author: luudee
author_rank: Frequent Contributor
timestamp: July 22, 2023, 03:35:39 pm
content: Hi Guys,I am looking for a second DMM for my lab.I already own a SDM3065 from Siglent, and am quite happy with it.I would like to buy a second DMM, should have at least the functionalityof the Siglent, but preferably slightly better.Looking for suggestions and recommendations. I don't mind good used equipment,as long as I can have it calibrated locally ...Many Thanks,ludee

author: HKJ
author_rank: Super Contributor
timestamp: July 22, 2023, 06:46:18 pm
content: Take a look at the Keithley 6500, it is not cheap, but you will get a lot of functionality over the Siglent.For a more regular DMM Keysight is not bad, but Siglent mostly copied it, i.e. you do not get much extra.If you want lower spec. meters, there is some other Chinese brands that works, but Siglent is the premium Chinese brand in DMMs (With Rigol a close second).

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 22, 2023, 07:15:39 pm
content: Other people have mentioned the Keithley DMM6500 as well. I would consider that one if I needed something more robust than what I have.

author: HKJ
author_rank: Super Contributor
timestamp: July 22, 2023, 07:48:33 pm
content: Quote from: KungFuJosh on July 22, 2023, 07:15:39 pmCalling it more robust it not really what I think about with it. The 6500 can do a lot of stuff that other DMM's can't. Some notes:Its digitizer makes it a oscilloscope (for low frequencies) with very very high precision.Its configuration is second to none, it has a multitude of triggering and other options.It can be programmed (With a real programming language) to do some very advanced stuff.You may not need these options immediately, but it makes the meter much more than just a extra DMM and a very good secondary DMM (It is also a very good primary DMM).I will admit that for regularly measurements I use my Keysights more than the 6500, but for some measurements the Keysights are not really usable and the 6500 is king.My point is that with the 6500 you do not only get a extra DMM, but you get some extra measurement options. How many extra options depends on how much time you want to spend on learning the DMM. The digitzer do not require time, but triggering and programming do.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 22, 2023, 08:03:20 pm
content: I know some rag on Picotest, but you might take a look at their model M3500A (or M3510A if you don't need the resolution). A few threads around, and they mention an excellent and easy-to-use remote interfacehttps://www.eevblog.com/forum/testgear/picotest-m3510a-vs-hpagilent-34401a/This is the same as Keithley's model 2100.

author: Faranight
author_rank: Unknown
timestamp: July 22, 2023, 08:55:58 pm
content: Another vote for Keithley DMM6500. That thing is a beast!

author: luudee
author_rank: Frequent Contributor
timestamp: July 23, 2023, 09:15:14 am
content: Thank you all for the feedback !!! VERY much appreciated !!!Keithley 6500 is it !Already sent an email to my local Tek/Keithley rep ...Cheers,luudee

author: luudee
author_rank: Frequent Contributor
timestamp: September 24, 2023, 02:07:45 pm
content: Guys,quick follow-up question, I noticed Kithley has also a DMM7500, which is 7.5 digits.Is the 7500 identical to the DMM6500 (except higher resolution) ?Also, looks like they have a DMM7510. How does that compare ?Many thanks !luudee

author: HKJ
author_rank: Super Contributor
timestamp: September 24, 2023, 02:38:42 pm
content: Quote from: luudee on September 24, 2023, 02:07:45 pmI have not seen a DMM7500, but have both the DMM7510 and DMM6500. They are not the same, even though the screens looks similar and they have about the same functionality.Some difference:The DMM7510 has a rotary encoder, this makes it possible to use it without the touchscreen (If it ever fails).The DMM7510 has light in its buttons.The DMM6500 has a slot for a switch module, i.e. it can be used to monitor multiple channels.The DMM6500 has some special support for apps (Some can be downloaded from Keithley) Note: They can both run scripts.On the DMM6500 the amp fuse can be changed from the front.My DMM7510 has a considerable more noisy fan than my DMM6500, for this reason I mostly use the DMM6500.The DMM6500 is a slightly never design and if you don't need the extra digit I believe it is a much better package.

author: JoeRoy
author_rank: Regular Contributor
timestamp: September 24, 2023, 02:39:41 pm
content: Quote from: luudee on September 24, 2023, 02:07:45 pmAFAIK, most 6.5 and 7.5 digits DMMs share the same Voltage Reference, then, after 1-2 years they will have basically the same accuracy, although the 7.5 can give you an extra decimal (useful to perceive small variations).Siglent SDM3065x and Keithley DMM6500 have a Scan card option, I do recommend it, you can find DIY projects for an interface.

author: luudee
author_rank: Frequent Contributor
timestamp: September 24, 2023, 02:56:03 pm
content: Quote from: JoeRoy on September 24, 2023, 02:39:41 pmThank you for the reply, JoeRoy.I read that the 6500 uses 16 bit resolution, and the 7500 uses 18 bit resolution. Wouldn't thatgive the 7500 *continues* better performance if it is calibrated annually ?Kind Regards,luudee

author: luudee
author_rank: Frequent Contributor
timestamp: September 24, 2023, 03:06:57 pm
content: Quote from: HKJ on September 24, 2023, 02:38:42 pmThank you so much for the feedback HKJ.I'll check the apps that are available on the keithley website and see if there is anything I can not live without, lol ...Many Thanks !Kind Regards,luudee

author: luudee
author_rank: Frequent Contributor
timestamp: September 24, 2023, 03:11:05 pm
content: Guys,I just found this PDF, it lists all (??) Tek/Keithley DMMs and their features ...Of course, we will still need your help and feedback, as some things might be missing (such all available apps),and real user experience is priceless !!!Perhaps this can be useful to others !Cheers,luudee

author: JoeRoy
author_rank: Regular Contributor
timestamp: September 24, 2023, 04:40:22 pm
content: Let me give you another opinion, although you said "should have at least the functionality of the Siglent, but preferably slightly better."Seems like you are even not using the full performance of your SDM3065, try to explore what it can do, as I said before, if you have the Scan card option would be very useful to your lab.You said "calibrated annually", sending (even locally) a DMM for calibration is not so simple, there are movements, temperature variation, risks, etc. If you really, really need accuracy, you will also look for stability and not another 6 1/2 DMM, but 8 1/2 digits (used) DMM could be your goal (check "Marco Reps" channel).I personally prefer a good 50k counts handheld DMM, they are convenient to use, robust, stable, and precise/accurate for 99.99% of electronics projects.I'm not a big fan of Keithley DMM6500 because of its highestBurden Voltage:https://lygte-info.dk/review/DMMKeithley%20DMM6500%20UK.htmlhttps://download.tek.com/document/SPEC-DMM6500A_April_2018.pdfhttps://siglentna.com/USA_website_2014/Documents/DataSheet/SDM3065X_DataSheet_DS06036-E02C.pdf

author: Hexley
author_rank: Regular Contributor
timestamp: September 24, 2023, 04:46:39 pm
content: Quote from: luudee on September 24, 2023, 02:07:45 pmFor some interesting background on the 6500 and 7510, you might check out this thread, with particular attention to the postings by user E-Design, who says he worked on the 7510 design.https://www.eevblog.com/forum/testgear/dmm6500-dmm7510-vs-34465a-34470a-ac-readings/msg3929483/#msg3929483

author: luudee
author_rank: Frequent Contributor
timestamp: September 24, 2023, 05:02:46 pm
content: Gentleman,both, JoeRoy and Hexley, many many thanks for your replies !I must admit, despite being 30+ years in the industry, I am mostly in front of the computer than in a lab.I will research your detailed replies in the next few days, and probably will have more questions, lolAgain, many many thanks !!!Kind Regards,luudee

author: HKJ
author_rank: Super Contributor
timestamp: September 24, 2023, 05:58:06 pm
content: Quote from: luudee on September 24, 2023, 02:56:03 pmThat is the fast digitizer, not the regular measurement, that have more bits.

author: aduinstat
author_rank: Contributor
timestamp: September 25, 2023, 10:59:03 pm
content: Quote from: JoeRoy on September 24, 2023, 02:39:41 pmThe Keithley has two scan card options: a 10 channel card, and a 9 channel card w/ temp sensor (for thermocouples). If you want a card, I recommend the thermocouple card. If you really need more than 9 channels, DIY a 20 channel card with solid state relays.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 26, 2023, 06:26:10 am
content: Quote from: JoeRoy on September 24, 2023, 02:39:41 pmThe LM399 ref. found in most 6 digit meters is not really good enough for a 7.5. digit meter. It is still found in a few Keithley meters togehter with an extra zener. The DMM7510 uses a much better LTFLU reference.For the SDM3065 the scanner is not an option to add later, it has to be ordered with a scanner as there are also extra parts on the main PCB needed. So one can consider the version with scanner as a different, though separate meter.