Products > Test Equipment
Keysight DMM - Yay or nay?
Dr. Frank:
--- Quote from: Traceless on March 04, 2022, 05:49:09 pm ---@nctnico, @HighVoltage: I was about to pull the trigger on the 34465A but due to your comments, the positive things reported before and another video (link below) someone sent me via DM I'm reconsidering the DMM 6500 now. The video is german but showed at least two occasions where the DMM 6500 was clearly superior to a 34461A. I doubt though that the test results would have looked different on a 34465A:
1. at 7:03 the peak-to-peak current while switching on a light bulb is measured. Due to the super high sampling rate the Keithley caught the inrush current, which was missed by the Keysight.
2. 8:04 Because of the larger display and zoom the Keithley can display even weak signals that show as flat line on the 34461A. The Keithley also seems to offer higher resolutions on the time axis.
--- End quote ---
Please do not follow such completely incompetent videos or sites! :palm:
These guys have obviously no clue what they are talking about, and in this case did not inform themselves at all about the KS instruments. I can only say: RTFM and RTFS
If a shorter sampling time had been used on the '461, 300µs is the fastest, instead of this NPLC 10, i.e. 200ms, as done on the Keithley DMM, then of course it would have caught the peak inrush current.
The 34465A of course is even faster than the '461, using its digitizing feature for DCV and DCI, which samples down to 20µs timely resolution. So yes this model is of course able to catch the inrush current also graphically and resolving it like the Keithley one, by simply using its button based ZOOM functions for time and volt axis.
That woman was simply not competent to use the KS correctly, and evidently she did not make herself familiar with it, neither with it's manual or specification.
Another hint: I regard the DMMcheck as a toy only, as you can't really calibrate DMMs as it's got a few single ranges only.
So if you have the demand to check some of your other equipment, then either buy such a 6.5 digit DMM, or ask the volt-nuts community here in Germany, they are located all over the place, and all might give a practical help, w/o expecting you to become a volt-nut also. But you're of course very welcome, otherwise.
Frank
Traceless:
--- Quote from: Dr. Frank on March 05, 2022, 10:53:27 am ---Please do not follow such completely incompetent videos or sites! :palm:
--- End quote ---
@Dr. Frank: Of course I take every information I find, espacially stuff on youtube, with a grain of salt. Luckily there is this awesome community which helps to identify such mistakes. Thank you for confirming that the 34465A can very well keep up with the DMM 6500 for those test cases.
@Everyone: I still have a few final questions, that may affect the purchase decision. Maybe the folks that have long-ish term experience with 34465A and the DMM-6500, can comment on some of them:
* Software/autocal issues aside, Are there any known weaknesses in any of the units (34465A, DMM 6500)? Example of issues that come to mind: Buttons not working properly/touchscreen becoming unesponsive after some time of use, input jacks wearing down fast or even breaking, issues with the power supply, fan bearings etc.
* How easy/hard is it to replace fuses, input jacks, fans? Are spare parts even available to "regular mortals" and is there a significant difference in sparpart prices between Keithley/Keysight?
* How well are the devices protected against a catastrophically misbehaving device under test (e.g. like the PSU shown in the video below)?
* Can I upgrade every option available for the devices after purchase or are there certain add-ons that can only be ordered with a new unit. (For instance the Siglent SDM3065X apparently can not be upgraded with a scanner card, instead one needs to purchase an SDM 3065X SC instead).
* Does any of the meters provide serious additonal value in terms of accessories. The A34465A comes with a "34138A test leads set", which I assume is decent. However if I'm not mistaken non of the meters comes with kelvin leads for 4-wire measurement. Looking for kelvin leads revealed they cost north of 450€ a pair on mouser (Are these made out of iridium threads handwoven by disney princesses, or what is going on here?). A more affordable pair from BK Precision (TLDK1) is available for ~100€, which still is a bit steep just for a set of leads.
* Does the DM-6500 come with a stylus?
nctnico:
In my opinion you shouldn't care so much about repairs / spare parts. The bench DMMs discussed are high quality gear and will last a long time. The only fuse you can blow is the one for the current measurement and that is externally accessible. Other than that, the inputs are very rugged. Still, I wouldn't use a high end bench DMM like this on mains with all the nasty spikes that can ride on top of it.
Kleinstein:
There are some complaints about the view angle on some of the meters. This is somewhat normal lmitiation with many LCDs as a larger viewing angle needs more power. AFAIR the angle on the 6500 is a bit limited.
For the DMM6500 there may be the option to install a scanner card (original and some plans around for a DIY solution).
Some early DMM6500 had roblems with transformer hum, but this problem should be fixed for newer units.
Traceless:
@nctnico: I'd also rather keep the DMM away from dangerous stuff, but for me there is a catch here. As mentioned in the beginning of this thread the DMM I'm about to purchase is going to be the "swiss army knife" of my lab. As such it should (and has to) do basically everything well that includes PSU diagnosis. The alternative would be to use my Aneng 8009 for primary side PSU work. I also have two more handhelds very similar to these, which are cheap to replace, probably even cheaper then the fuse on a 34465A or the DMM-6500. Also they make mains work a lot more "exciting", but usually I try to keep the excitement level to a minimum during mains work ;).
@Kleinstein: Viewing angles are also a good point, thanks for bringing that up. Nice to hear that Keithley actually improves their devices if stuff like the transformer hum is discovered.
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