Any review about Tektronix DMM4040 ? - Page 1
Forum section: electronics / testgear

author: octal
author_rank: Contributor
timestamp: May 26, 2022, 09:47:55 pm
content: Hi,I'm about buying a bench multimeter, and a friend proposed to me his (used) Tektronix DMM4040. What are your opinion about it please?I can't find any review about it (either here or on Youtube). I can't find any review about its Fluke equivalent.Do you think the Fluke rebadge is a better choice? or should I go for a used Agilent instead.Also I have been proposed a new GW Instek GDM-8261A for a very attractive price (about 400€). Would I go for it instead of the DMM4040 (which costs about 1000€) ?Regards

author: nctnico
author_rank: Super Contributor
timestamp: May 26, 2022, 09:54:34 pm
content: For 1000 euro you can almost buy the DMM6500 new. I'm not familiar with the DMM4040 but from a quick glance it looks like an older, obsolete model.Try Google to search for DMM4040; there are several videos.

author: bdunham7
author_rank: Super Contributor
timestamp: May 26, 2022, 10:04:06 pm
content: DM4040 is the equivalent of the Fluke 8845A and I'm not aware of any real difference between them other than appearance. It's a great meter, far better than anything GW makes I'm sure, but cost and availability factor in too here. The GW seems cheap and the Tektronix seems expensive, but if it is in mint condition probably not unreasonable.Is there anything in particular you wanted to know about the Tek/Fluke?

author: octal
author_rank: Contributor
timestamp: May 26, 2022, 10:10:18 pm
content: Quote from: nctnico on May 26, 2022, 09:54:34 pmAs I said, there are no videos about it. The is only one with no sound (completely muted with the guy doing some tests using a dongle), nothing else. If you have links I would be very happy and thankful.Quote from: bdunham7 on May 26, 2022, 10:04:06 pmI want to know if the DMM4040 is any good, or is it better to go for an old well known brand for bench DMMs named AgilentI know Tektronix for its scopes, but never used its DDMs. Are they reliable on the long term (I know agilent lasts for 15 up to 20 years without pb).

author: nctnico
author_rank: Super Contributor
timestamp: May 26, 2022, 10:19:11 pm
content: Tektronix, Keithley and Fluke are one company for a long time.I don't think there is a difference in quality between Tektronix or Keysight where it comes to DMMs. However I think the DMM4040 you are looking at is way overpriced and lacks several modern features.What kind of DMM do you actually need? A higher end DMM may not be the best fit for all purposes. For example: I own a Keysight 34461A (6.5 digit) but I almost never use it. My daily driver DMMs are a couple of Vici VC8145 because they are more comfortable to use.

author: octal
author_rank: Contributor
timestamp: May 26, 2022, 10:31:23 pm
content: Hi ntcnico,I already own a Fluke 87V, a UNI-T 61E, a set of other small DMMs, and a benchtop Instek GDM-8246.I'm working in IoT field, and I need very good precision and (mainly) auto-range DMM for current measurements. Usually on my boards, current consumption jumps from 10 or 20nA up to several hundred mA, and then goes back to very low consumption (this is the normal life of any IoT board).So My main need is for current consumption measurement, and it needs the capability to log all data on long terms (either via GPIB, USB or any USB or SDCard directly on the DMM itself).Another usage I want to do with a new precision DMM is to calibrate my other DMMs ( a friend promised to send me the service manual of the GDM-8246 and there is a calibration section in it).

author: nctnico
author_rank: Super Contributor
timestamp: May 26, 2022, 10:48:28 pm
content: In that case and with a 1k euro the spend, I'd go for the Tektronix / Keithley DMM6500. It has more ranges compared to the 34461A from Keysight. For example: the 34461A has a lowest current range of 100uA where the DMM6500 has a 10uA range. On top of that the 100uA range on the 34461A is less accurate compared to the DMM6500. I really wish the DMM6500 was available when I needed to buy a 6.5 digit DMM.

author: octal
author_rank: Contributor
timestamp: May 26, 2022, 10:59:11 pm
content: I'll check the DMM6500 then. Thank you for the ref.btw I also like the Vici VC8145. A simple multimeter with great capabilities (and its quirks of course). The only pitty is the price that raised up a lot these days (we can't find it for less than 165€ without shipping fees). Last time I checked them it was when I wanted to buy 4 or 5 of them to monitor battery discharge process. With a simple Raspberry Pi with a 4 x UART interface could transform them to a very nice batteries caracterisation test bench (Fluke 287 are expensive).

author: bdunham7
author_rank: Super Contributor
timestamp: May 26, 2022, 11:28:09 pm
content: Quote from: octal on May 26, 2022, 10:10:18 pmIt's just a rebadged Fluke and should be excellent long termif it is in good condition. If it is 15 years old and has been physically abused or the display left on 24/7 without reducing the brightness, it may not be so good.QuoteWell, that is one weak spot of the 8845A/8846A/DMM4040/DMM4050 series. They use only three different current shunts, rather than the six or seven something like the DMM6500 uses. As a result there is a little more noise and a bit less specified accuracy on the few of the current ranges. So for example, the 1mA and 100mA ranges are very accurate, but the 10mA is a bit less so. But also note that in general, typical bench multimeters will struggle with this type of current measurement due to ranging. There are better solutions for this scenario.And as far as calibrating other DMMs, that's tricky too. You can do a sort of cross check, but any more takes some doing.

author: thm_w
author_rank: Super Contributor
timestamp: May 27, 2022, 12:09:05 am
content: Quote from: octal on May 26, 2022, 10:59:11 pmI realize its still much more expensive than 5 VC8145's, but you can DIY the scanner cards:https://github.com/cozdas/CozScan2020For measuring a large number of voltages.Or get a USB DAQ with suitable resolution.

author: MrYakimovYA
author_rank: Regular Contributor
timestamp: May 27, 2022, 02:32:08 am
content: Quote from: octal on May 26, 2022, 10:31:23 pmHi octal,could you say how fast current consumption is changing? 10 nA .. 100 mA (200, 300 mA) is very wide, and it may cause to change the range of DMM. It could be not fast really. So you can loose some importand data point. I don't know what to offer instead. But I'd pay attention to the issue.

author: octal
author_rank: Contributor
timestamp: May 27, 2022, 08:13:56 am
content: Quote from: MrYakimovYA on May 27, 2022, 02:32:08 amThe IoT devices I work on have 2 scenarios:1- just wake up for sending data (using LoRaWAN) and eventually receive data (LoRaWAN downloads) and then go to deep sleep again: this process can take from 15s to 30s (depending on some params)2- wake up, and execute some stuff (start a pump, or activate a motor, ... do some measurements and then shutdown again).On those processes, I don't mind if I lose a point or two, I do read current each 500ms only. The idea is more to measure the current consumption in each scenario and estimate the true consumption from a theoretical model that has been fitted to experimental measurements.The Second scenarion is more complicated: My device does only wakeup to measure a data on its ADC and emit data and then shutdown. In this case, the device is powerd only from an embedded battery and I must evaluate each bit of consumed energy.For this second scenario, and from the answers I got on this thread, I checked various DMMs specifications and looks like autoranging in Amp mode is really slow on most of them. I think that there are no savings to do to achieve this work, I must find a way to buy a a true power meter, or a true intelligent power supply with battery emulation technology in it. It will let me evaluate true power consumption at various stages of battery life. But this costs $$$ (the lowest price I saw was about more than $3000 if I remember).The DMM4040 proposed to me has been used only 4 months and is like new. I know the person who used it and I know how much care it takes when using such tools. So there is no fear from that. And he told me he can sell it to me arround 900€. The only point is that at this price, finally, it's better to look for a more modern DMM like the DM6500 suggested by people here on previous posts.Thank to everyone ... Yet I'm still impressed by the fact that no one reviewed this DM4040 (nor its Fluke rebadge) on the web despite the fact it's old.

author: anotherlin
author_rank: Frequent Contributor
timestamp: May 27, 2022, 09:35:38 am
content: Quote from: octal on May 27, 2022, 08:13:56 amYou should have rather look for the Fluke 8846/8845 rebadge, or rather the original (I guess, it's Fluke developed and then rebadged as Tektronix).There is several videos on Youtube and other webpages about it. Here is a very detailed teardown/repair/some analysis of the 8846A (DMM4050):https://xdevs.com/fix/f8846a/The DMM4040 (8845A) seems to be about the same but with less good accuracy specifications.

author: bdunham7
author_rank: Super Contributor
timestamp: May 27, 2022, 03:33:30 pm
content: Quote from: octal on May 27, 2022, 08:13:56 amIf you are going to try and do this with a DMM as opposed to an SMU, you also need to consider how much voltage drop across the measuring shunt you can tolerate. The only real reason to use a 6.5-digit instrument is to try and do all of the measurements on one range, but even that won't work if you are going from 20nA to 200mA. I have little 1W 0.1R shunt resistors that I can install in a test circuit and then either use a scope or DMM to measure current fairly well from 1µA to 100mA in one range with a burden of 10mV at 100mA, which IMO is pretty good performance. What you are asking for is 3 orders of magnitude more difficult. You might look at the Current Ranger...https://lowpowerlab.com/guide/currentranger/QuoteThere are some, but I'm not sure how helpful they are. It's not an exciting subject and the real information you need is hidden in the details of the manual and the various menus. Without doing my own whole review, in a nutshell the 8846A/DMM4050 have certain features and performance that are unmatched by other 6.5-digit DMMs (1000VAC, 1G-ohm, 24ppm @ 99%CI for those that would argue) while the lesser 8845A/DMM4040 are pretty much just equivalent to their competition. They're also stable (an issue with non-A-brand meters) and straightforward to use, except for the fact that you see the word "Overload" a lot (just a quirk). I would expect the price-sensitive bang-for-buck crowd to not be impressed.https://www.mjlorton.com/multimeter-review-buyers-guide-fluke-8846a-8845a-6-5-digit-precision-multimeter/

author: octal
author_rank: Contributor
timestamp: May 27, 2022, 08:53:08 pm
content: Thanks bdunham7,Up to now I also used a lot the shunt resistor technique to do measurements, but it's not really comfortable to do with an oscilloscope on the long termps (several days).The Current Ranger project is awesome. I'll order one and try it. Some days ago I was mainly tempted by the JouleScope devicehttps://www.joulescope.com/Looks like an awesome device (but it's priced near 1k€, this is why was tempted by a 1k€ DMM).