Keithley DMM6500 : Dual measurement capability (demonstration)
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- Опубліковано 20 гру 2020
- In this video, we explore a super useful feature of the DMM6500 which allows the multimeter to perform two measurements at the same time. After a bit of theory, we will try it out in practice, and look at some of the limitations of this feature.
With the DMM6500, do you get two multimeters for the price of one ? Let's answer this question ! - Наука та технологія
I found your channel searching for information about the DMM6500 (good info, by the way!). But I burst out laughing when I saw your CAD program! :-D
I can't thank you enough for this video! It was exactly what I was looking for!
I've made up my mind, this will definitely be my first bench multimeter, possibly very soon. Its capabilities and versatility are just extraordinary, far superior to the competition.
Also, liked a lot the DaveCad reference!
Thank you again!
Happy it helped ! The DMM6500 is definitely a solid purchase. It's not perfect, but no instrument is :)
After researching 6.5 digit DMMs for weeks, I ultimately decided on a Keysight 34465A. I was just about to click 'Buy', when I decided to take one last look at the other options. I was familiar with the Keithley 2000/2100 series, but missed the 6500 before. One careful look at the specs and my decision was made. Sorry Keysight, the Keithley meter is the new sheriff in town.
Thank you for the range tip. I hadn't realized that.
A tip from me is that you can meassure the current on the low side of the load.
By this way you will able to measure the voltage correctly on the high side.
Thank you for the video.
Kostas
Super helpful video. Nicely done. 👍 I've had this relay switching issue during dual measurement on another DMM and I was wondering why sometimes it happens only some of the time (otherwise, it works as expected). Your video explains it _perfectly_. Btw, I have a DMM6500 on order - to replace my older 5.5 digit meter - and am looking forward to it even more now :) !
Very helpful! Thank you!
This is a great tip! It does not work for measuring DC and AC at the same time though... as far as I can tell.
hello good evening but how could it be if we want to check the consumption on the same line
شكرا على الفيديو.سؤالي ما مدى اختلاف القياسات أن وضعنا أكثر من مقياس من نفس النوع بقراءة الجهد والتيار !
Can I measure temperature and dc voltage at the same time ?
I think you have missed one shortcoming. In this setup voltage measurement is wildly inaccurate due to flowing current thru voltage measurement lead. In most cases, even a 4.5 or 3.5 digit handheld multimeter will give better accuracy and non of the limitations. This is also true for current to some extent as you can't select the optimal range for voltage and current at the same time so current is measured at lower accuracy too. Although it could be useful in scenarios where 2~3 digit precision is enough. It just looks somewhat strange than it's done on a 6.5 digit multimeter :D
The video is very descriptive and helpful. However, I couldn't select the secondary measurement. What should I do?
From memory because I am moving and I don't have access to my DMM6500 today : Use the touch screen. You can scroll horizontally to switch to the secondary meaurement display on the bottom half of the screen. Then I believe there is a button to swap primary and secondary display and you can change the measurement accordingly.
If you hear the relays clicking do not leave it as is as it will damage them. Manually adjust the range of both measurements so that you find a combination where the clicking stops
Use the math function to invert the negative voltage to a positive voltage.
Excuse my ignorance but aren't the sense 4 wire terminals for measuring voltage and current at the same time?
If you haven't been exposed to it before, you'll probably find the 4-wire measurement system pretty interesting. This is also known as a Kelvin connection scheme. By connecting two wires to each side of a resistive element, it's possible for the meter to "subtract out" the resistance of the wires themselves. For precision measurements of small resistances, this is essential.
Does that help?
BTW, for voltage measurements, the 4-wire system is unnecessary, as the change in input impedance would be trivial.
Thank you for pointing this "clicking" issue - on paper, the DMM6500 looks so good!
Your video now raised a question about my use case and I hope you can help: I would like to dual display to show 2 different readings at the same time:
1. AC mA in the low range (to the high µA range) on the primary display
2. DC V in the 1kV range on the secondary display. The secondary display may also be switched to Hz from time to time.
Based on your description, the 6500 will be clicking like you showed whenever I have the display combination on AC mA and DC kV setting.s Am I correct? I would very much appreciate your advice, perhaps even your findings if you try it yourself.
Thanks in advance!
I did some testing for you and ran into a bug with the meter. For now I cannot recommend using DCV and ACI at the same time with this meter since I was not only not able to prevent the relays from clicking in any combination of the range settings, but also I found some weird bug.
I have reported the bug to Tek and hopefully they will fix it soon.
Don't get me wrong, the DMM6500 is still a GREAT meter. I would buy two of them if I was in your use case. I just don't think the dual measurement feature is good enough - yet. Hope this helps
Thank you very much for doing the test and reporting the bug. The 6500 manual did not specify how secondary measurements would behave, except to avoid "excessive relay wear". With your video and my question, we know the problem surfaces in more than one place. Bummer. Hopefully Tek will get this fixed. Thanks again.
@@xavierguzmanjr5495 you're welcome. During my testing, with some range combinations, I had a measurement error of several percents (!!!) with the secondary measurement, which is totally out of spec.
I have send a bug report to my contact at Tek and I am waiting for an answer. I might make a short video about it
How do you handle the power on/off situation on the 6500? It has only a standby mode and can't be separated from the grid without pulling the plug. Do you disconnect it using an extra switch or do you leave it in standby mode all the time? What do you recommend?
I am not sure if the DMM6500 uses a heated reference. But since Keithley didn’t use a “true” ON/OFF switch (they did on my 2280S power supply) there must be a reason. The instrument might suffer from some adverse effect if cycled too frequently.
So I leave it plugged at all times, but on a surge protected outlet. And I hope it will be enough (we seldom have storms where I live)
Hope it answers your questions. There is no perfect solution sadly.
@@the_bootloader
Alright, thank you for your opinion! I'll leave it on then and may mail the distributor for further information on this. I'll let you know then if you wish.
@@N.A._McBee absolutely ! The more we know about our instruments, the better we can use them. Feel free to share your findings
@@the_bootloader I agree. I believe the standby mode to be a good feature, rather than a hindrance. Otherwise, for true precision measurements, one would have to leave the meter turned On for 30 minutes or so first. Also, similarly, I use a high-quality power conditioner for my test gear. Where I live, storms are fairly common in the Spring. During serious electrical storms, I make sure to unplug the test bench!
Great tips :-) When you now can read both current and voltage - have you then tried to make a Test Script on the instrument to show power?
Yeah, you echoed my exact thoughts. Plus, with the script, it's probably very easy to invert the negated measurement in the output - a small, but nice improvement.
very goot
Thanks for the great videos about the DMM6500! This is 3 months ago, so I'd like to know whether there was any response from your Tektronix contact person in the meantime. I consider buying this thingy, so I sought after firmware revisions which could have taken place after your inquiry but the latest revision is of June, 2020. Thanks a lot beforehand!
I am working on a few other quirks I have identified with the dual measurement feature. I do not recommend buying the instrument for this feature in the meantime, since I am not convinced it can achieve the full accuracy specified in its datasheet. But I need to find time to do more experimentation to confirm. I did receive some answers from Keithley/Tek but I am not 100% satisfied with them.
I am still very happy with the DMM6500 in general. It is a very good instrument. Just don't plan to rely heavily on the dual measurement function, that is my advice currently. It is a very innovative feature with a lot of potential however, and I hope Keithley continues to improve it !
Hope this helps
@@the_bootloader
Thank you very, very much for your response!
I have bought the meter yesterday and it will arrive today but I did not buy it because the dual measurement feature had been a must for me. I have done a whole lot of research in the last three weeks with respect to a good DMM for the bench, and the latest two competitors were the HMC8012 from Rohde & Schwarz and this Keithley. By the way, and somewhat Interestingly, the Siglent SDM3055, although that's another price range, has the same accuracy problem with the dual mode (loss of accuracy in this mode). - My decision for the Keithley against the R&S was based on the fact that the HMC8012 is an older model with less precision than the DMM6500. Moreover, the whole user interface of the Keithley is much more modern, more flexible and has this wonderful feature of a live graphical presentation of measured values over time, which is fantastic.
I'm running a small YT channel in which I plan to do some videos with and about the DMM6500, and it could be interesting to see whether the latest lot of instruments has experienced unpublished changes. Could you send me a little sketch of your dual-measurement test scenarios so I could try to reproduce the problems? That would be great! You may use the mail address available in my channel info section, thanks a lot beforehand!
Have a nice day!
@@N.A._McBee you will love it ! Please make sure to upgrade the firmware of the DMM6500 immediately. There is an old version which has a bug which drains the internal battery of the instrument, and I believe that if this happens you have to return the instrument for service. The newer firmwares fix this.
As to the dual measurement quirks, I am working on a video to show just that and hopefully I can release it soon !
@@the_bootloader
Thanks for the firmware advice! I checked this a few minutes ago and the DMM already had the newest firmware revision installed, 1.7.3.c. (The device was born and calibrated on November 22, 2020.) I have done first little tests with the secondary screen option and will continue testing, of course! I'm looking forward to your video about this, quite interesting stuff. For the time being, I'm okay with switching the primary function, so everything's fine with this instrument so far, I think it was the right decision. Perfect things with no errors, quirks or glitches at all simply don't exist 😉.
@@N.A._McBee Looking forward to your videos on the DMM6500! On UA-cam, there are nice teardowns and somewhat superficial demos (this video aside), but not a lot about the features in-depth.
as u suggest will get more than 1... not all same
Looking at the Rohde & Schwarz HMC 8012 or Keithley 6500, this video does not make that decision easier.
There is only one solution : get both, and let us know which one you prefer ! :D
Would be better if you can measure the SAME Voltage and Current shown in the power supply.
Good idea ! The purpose of this video was to maximize the number of simultaneous measurements. In this video, I have 2 measurements from the DMM and 2 other measurements from the PSU, which gives a total of 4 different measurements with just 2 instruments. The purpose was not to validate the accuracy of the DMM6500 which is well defined in its datasheet. Thanks !
@@the_bootloader I understand, but because this is a NEW setup it's interesting at least one time to evaluate if the setup works correctly. Try to search "DMM6500 Dual measurement", your video is the only one on UA-cam, so you have an opportunity to explore better this topic.
fast click relays...keithly are cheapskates... one circuit flip flops,,,searching ranges,,, switching relays,, instead of 2 indep circuits