Your DER/IET DE-5000, DE-6000, MS5308 has this strange behaviour? - Page 1
Forum section: electronics / testgear

author: Carrington
author_rank: Super Contributor
timestamp: March 16, 2016, 12:08:35 am
content: Hi all!I was trying to measure some of these thin film inductors (http://data.leocom.kr/datasheets/316338_360095.pdf) with my DER DE-5000.I wasn't looking for an accurate measuring, but the results don't make any sense. And I know, 100 KHz is not the best (or most appropriate) frequency, to measure these types of inductors. But please, let me continue.Later I started to thought than maybe have to do with their DC resistance, so I did a little test:I measured ~ 1cm wire in series with 1 ohm resistor. And I get a reading of ~ 0.15uH (Ls) with 1 OHM (ESR), instead of ~ 10nH (Ls) and 1 OHM (ESR). However if I measure only the wire (without resistor), the DE-5000 show ~ 13nH.So, what is happening here? What is wrong?I repeated the test several times, calibration included of course, even I try with short cables for the DUT (see the attached picture at the end). But always I got the same result.The exact values were:- Wire: 1.3cm (long), 0.3mm (thick) ie. arround 11.5nH. ->http://chemandy.com/calculators/round-wire-inductance-calculator.htm- Resistor (thin film): 1 ohm 1% 805 case.And the final question is:Do you get similar results with your IET DE-5000, DE-6000 or DER DE-5000?Several weeks ago (February 3, 2016), I sent an email to the DE-5000 manufacturer, to let him know about this. And guess what, no reply yet, and I'm afraid than ever.If I'm not wrong the accuracy on the DE-5000 is expressed as an % of rdg. plus x digit, right?So for a reading of 0.100uH @ 100KHz we have an uncertainty of +-0.0075uH (2.5% +5)Or IET/DER is expressing the error in another way?Edited to change the subject title.

author: Carrington
author_rank: Super Contributor
timestamp: March 16, 2016, 12:12:38 am
content: I asked to Thomas (TurboTom), about repeat the previous test with their Applen AT826.And he, very kindly agreed, here are the results. Thanks again Thomas!

author: Carrington
author_rank: Super Contributor
timestamp: March 16, 2016, 12:15:00 am
content: I also asked to Jake (jaxbird), about the same. Here are the results. Thanks you very much Jake!Note: Your impedance analyzer is amazing!

author: Carrington
author_rank: Super Contributor
timestamp: March 16, 2016, 02:42:54 am
content: What a coincidence! I just received a message from DER.I previously expressed my intention to make this problem public here, so seems that they have been waiting for it.They just asked for serial numbers, supplier and other things, but no explanation about the issue.Anyway, at least it's a progress, let's see what happens.

author: D3f1ant
author_rank: Frequent Contributor
timestamp: March 16, 2016, 03:16:30 am
content: Tried this on my Der EE and get similar result, 0.139uH on a 0.4mm wire with a 1R resistor (0603) soldered in series.

author: Carrington
author_rank: Super Contributor
timestamp: March 16, 2016, 03:21:54 am
content: Quote from: D3f1ant on March 16, 2016, 03:16:30 amThank you for trying.I think we have a firmware bug, or maybe something worse.Quote from: ietlabs on November 07, 2014, 03:13:47 pm

author: jarvis
author_rank: Contributor
timestamp: March 17, 2016, 02:29:35 am
content: I noticed you use one small PCB with wire (2wires or 4wires ?) connected to DUT.How did you make the open/short calibration? Including the small PCB with wire shorted ?

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 02:49:15 am
content: @jarvis:This PCB is part of the TL-21 fixture, and I used four wires of course.Maybe a picture is better than an explanation, see attachments.I can assure you that this "error" (bug or whatever) has nothing to do with the test fixture.

author: jarvis
author_rank: Contributor
timestamp: March 17, 2016, 02:54:27 am
content: Dear CarringtonHow about the Inductance test result for this 1 ohm resistor only ?

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 02:58:30 am
content: Quote from: jarvis on March 17, 2016, 02:54:27 amBy any chance, do you think that a 0805 smd resistor has an inductance of 140nH!

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 03:06:01 am
content: Source:http://www.planetanalog.com/document.asp?doc_id=527522

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 07:02:51 am
content: Ok, the resistor alone:- First picture, 0 ohm.- Next picture, 1 ohm.For both pictures: Unknown tolerance (pick up from a board), 0805 case, and fresh calibration.0 ohm: all ok, Ls is within the error. (3 counts vs 5).1 ohm:(As I expected).

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 07:31:29 am
content: However, with higher values of resistance, it could reach perfectly 140nH, and even more.For example:http://electronix.ru/forum/index.php?act=attach&type=post&id=55596

author: mos6502
author_rank: Frequent Contributor
timestamp: March 17, 2016, 08:05:44 am
content: Can you look at the voltage across the resistor with a scope while measuring?

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 08:17:10 am
content: Quote from: mos6502 on March 17, 2016, 08:05:44 amYes, I can, but later, now I can not.But the probe will affect the measurement.No one can make this simple test with their DE-5000/6000?

author: mos6502
author_rank: Frequent Contributor
timestamp: March 17, 2016, 08:49:14 am
content: Relax bro, I'll do it, later.What's the revision number of your DE-5000?

author: rosbuitre
author_rank: Regular Contributor
timestamp: March 17, 2016, 09:15:30 am
content: HiI get tired of sending mails to the manufacturer, asking for new software / firmware and never responded, 0 post sales serviceRegards

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 09:37:09 am
content: Quote from: mos6502 on March 17, 2016, 08:49:14 amSorry, I'm a little stressed.Here you have, but, what are you looking for?

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 09:43:25 am
content: Quote from: rosbuitre on March 17, 2016, 09:15:30 amYeah, this type of situations can be a bit irritating.I didn't even expect an answer. The funny thing is the beginning of their email: "We try to solve your problem soon".I hope they don't need another half month to reply again.

author: mos6502
author_rank: Frequent Contributor
timestamp: March 17, 2016, 09:46:59 am
content: Quote from: Carrington on March 17, 2016, 09:37:09 amI don't know ... maybe resonance or something? If the signal is clean, it's probably a software issue.I did a quick test, 1 ohm resistor, shortening the leads by 20mm (10mm each side) reduces the inductance by 53nH. My meter is version 8.

author: mos6502
author_rank: Frequent Contributor
timestamp: March 17, 2016, 09:57:36 am
content: Woops, another interesting discovery: with the longer leads, the 1 ohm resistor measures as 17uF, shorten the leads by 20mm and capacitance is OL.

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 10:00:15 am
content: Thank you very much!About the revision: I never take it apart, so no idea.And from your the results, I think we have more of the same.However, this damn thing has no problem with capacitors. Anyway!Thanks again.

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 10:02:22 am
content: Quote from: mos6502 on March 17, 2016, 09:57:36 amOh, my God! Nobody has noticed all this before? Weird!Edit 1:But wait that's Cs. Have you checked Cp?142nF on mine for the 1 Ohm resistor.Edit 2:And for the "deree5.jpg", I think that probably you have a short.

author: Carrington
author_rank: Super Contributor
timestamp: March 17, 2016, 10:11:43 am
content: Same revision here.I'm dying to see the results of an EIT!

author: BravoV
author_rank: Super Contributor
timestamp: March 18, 2016, 01:35:32 am
content: I believe Mastech MS5308 has the same chipset as DE-5000.Calibrated before starting the measurements, results attached below, hope this helps.

author: Carrington
author_rank: Super Contributor
timestamp: March 18, 2016, 02:18:52 am
content: Thank you very much!But, I think that such resistances are not the most appropriate to make this test. However, I don't know their typical parasites values.To me seems more logical to use a smd one, without any aditional wire. Ie, just a SMD resistor.Additionally, your LCR can't zero their Ls below 30 nH?"BravoV", please don't worry about. Definitely, seem that all this stuff don't matter to anyone.Thanks for your time.DER DE-5000 to the trash!

author: AlfBaz
author_rank: Super Contributor
timestamp: March 18, 2016, 02:40:04 am
content: Just tried this on my DE-5000 and got reasonable results if that online wire inductance calculator is anything to go by.Opened it up and it's a version 5

author: Carrington
author_rank: Super Contributor
timestamp: March 18, 2016, 02:46:28 am
content: @AlfBaz: Thanks, but, what you've tried exactly? Only the wire?

author: AlfBaz
author_rank: Super Contributor
timestamp: March 18, 2016, 03:29:59 am
content: Didn't have 1ohm resistor on hand, closest was 1.2 5% carbon film.Unmodified TL-21 and ran the cal procedureAt 100kHz:- leads shorted ESR = 0.00ohm Ls = 0.000uH- 10mm of .68 tinned solid copper wire ESR = 0.00ohm Ls = 4nH (should be 6nH)- one lead right up against resistor the other 10mm away from resistor ESR = 1.19ohm, Ls = 0.031uH (31nH)- both leads up against resistor ESR = 1.19ohm, Ls = 0.015uH (15nH)- both leads on wire, right next to each other ESR = 0.00ohm, Ls = 7nH which seems to indicate inductance of the TL-21 alligator clips

author: BravoV
author_rank: Super Contributor
timestamp: March 18, 2016, 06:38:10 am
content: Carrington, my pleasure.Quote from: Carrington on March 18, 2016, 02:18:52 amIts like permanent offset developed thru time, and no, I'm not worry cause it seems like the offset is stable and constant, verified using my Fluke PM6306 benchtop LCR meter.Most of the times I used this Mastech for quick and brief measurement only.

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 18, 2016, 08:37:41 am
content: My DE-5000 exhibits this same behavior. At 100 kHz a 1 ohm resistor plus some lead length measures about 140 nH. A 10 ohm resistor measures 152 nH.Both resistors measure around 15 nH on the Wayne-Kerr.

author: Carrington
author_rank: Super Contributor
timestamp: March 18, 2016, 08:40:04 am
content: Quote from: The Electrician on March 18, 2016, 08:37:41 amFor the love of God! THANK YOU THANK YOU THANK YOU!

author: Carrington
author_rank: Super Contributor
timestamp: March 18, 2016, 08:43:11 am
content: Today I received a new response from DER (thanks). You can see it at attachments.It is the answer to the first three messages of this post (more or less).Honestly, I am very grateful for the effort they have made, but I think they have not understood me.I know that my English is far from being close to be good enought, but it really is so bad?

author: Carrington
author_rank: Super Contributor
timestamp: March 18, 2016, 08:51:37 am
content: And now...How do I explain all this to DER?

author: Carrington
author_rank: Super Contributor
timestamp: March 18, 2016, 09:01:53 am
content: @ AlfBaz: Thanks.Quote from: AlfBaz on March 18, 2016, 03:29:59 amProbably that is due to fixture errors.See the page 23 on this document (Effect of Test Fixture Inductance):http://www.cliftonlaboratories.com/Documents/AADE%20Reveiw.pdf

author: PedroDaGr8
author_rank: Super Contributor
timestamp: March 19, 2016, 06:11:45 pm
content: Quote from: Carrington on March 18, 2016, 08:51:37 amIt is a long shot but you can try enlisting the help of some of the native Chinese speakers on this board. They might be able to better translate what you want to say into Chinese, getting rid of the language gap between you and Der EE.

author: D3f1ant
author_rank: Frequent Contributor
timestamp: March 19, 2016, 11:03:39 pm
content: It weird that it seems to read fine with a 2 ohm leaded 1/4w resistor but not with a soldered 1 ohm smt one. I'm sure it's some kind of firmware bug at a range crossover point maybe. I've never experienced a 'problem' in real world usage, so the problem isnt bad enough that I'd toss it in the bin and buy a Keysight meter. I expect and accept there maybe (will be) firmware problems with cheap gear.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: March 20, 2016, 04:31:19 am
content: Quote from: D3f1ant on March 19, 2016, 11:03:39 pmConsidering the Keysight handhelds use the same ICs as the Der EE AND lack four write measurement, they aren't necessarily an upgrade. The bigger thing is that the IET labs model is the exact same as the DE-5000 and if this bug exists, it will exist in that one too.

author: Wytnucls
author_rank: Super Contributor
timestamp: March 20, 2016, 04:36:50 am
content: The Keysight meters don't use the Cyrustek ICs.

author: Carrington
author_rank: Super Contributor
timestamp: March 20, 2016, 11:12:49 am
content: Quote from: PedroDaGr8 on March 19, 2016, 06:11:45 pmThat's a good idea. I'll try. Any volunteer?

author: Carrington
author_rank: Super Contributor
timestamp: March 20, 2016, 11:28:43 am
content: Quote from: D3f1ant on March 19, 2016, 11:03:39 pmYes, very rogues! Why did not they use 1 ohm resistor?Quote from: D3f1ant on March 19, 2016, 11:03:39 pmYes, maybe a wrong value on one interpolation table, or something like that.Quote from: D3f1ant on March 19, 2016, 11:03:39 pmThat is relative.Quote from: D3f1ant on March 19, 2016, 11:03:39 pmYes, this is an "economic" instrument, and designed and made in China, but that should not be an excuse.Maybe they never will recognize this fault, especially if only they can load a new firmware.Also, if all the IET meters have this bug, what will be their reaction?

author: Carrington
author_rank: Super Contributor
timestamp: March 20, 2016, 11:29:57 am
content: The next test is irrefutable, see the following posts, and judge by yourself.

author: Carrington
author_rank: Super Contributor
timestamp: March 20, 2016, 11:31:54 am
content: Enhanced test fixture, both sides:

author: Carrington
author_rank: Super Contributor
timestamp: March 20, 2016, 11:33:19 am
content: Calibration test:

author: Carrington
author_rank: Super Contributor
timestamp: March 20, 2016, 11:35:17 am
content: Two resistors (connected in series), 0603 case, 1 ohm, 1%:

author: Carrington
author_rank: Super Contributor
timestamp: March 20, 2016, 11:37:16 am
content: And finally each resistor (independently):

author: jpb
author_rank: Super Contributor
timestamp: March 20, 2016, 07:48:06 pm
content: I calibrated as shown in the first picture. Measured one section of the leg getting 50nH.Measured from the ends of the resistor as shown.Measured right by the resistor and the inductance goes up!Assuming the true value is around 13 nH then the reactance part at 100kHz is only around 8 mohms so a 1 ohm series resistance swamps it I guess.The rule of thumb that we used for bond-wires at microwave frequencies was 1 nH per mm.

author: Carrington
author_rank: Super Contributor
timestamp: March 21, 2016, 05:21:54 am
content: @jpb:Thanks.That was my first thought, but we know nothing about its HW.Let's assume that its HW is unable to discern, then the specifications given by DER are a false.But what happens with IET, also lies? Remember that they are using the same hardware.Honestly, I don't know what to believe.In addiction, another thing that I thought when I read their last answer: How the hell DER can say that my DE-5000 has any problem from measurements made with another meter? It's absurd!

author: KMSL
author_rank: Newbie
timestamp: March 21, 2016, 11:06:49 am
content: DER DE-5000 CAL with TL-22 SMD tweezers. Manual Ls at 100kHz. Tip of tweezers joined 0nH ESR 0 Ohm . SMD 1206 resistor 1R0 14nH ESR 0,99 Ohm. With 1,3 cm wire Al Ø 0,6mm 31 nH ESR 0 Ohm. And finally joined: wire+Resistor 1R0 31 nH ESR 1 Ohm. I think TL-22 are OK, but TL-21 are fake.

author: Nuno_pt
author_rank: Frequent Contributor
timestamp: March 21, 2016, 11:11:18 am
content: It would be good to check with an TL-21 mod for Kelvin clips, to see if that change the behavior.Maybe it's an alligator thing. :-)

author: BravoV
author_rank: Super Contributor
timestamp: March 21, 2016, 12:05:01 pm
content: Reading Nuno_pt's comment made me opened and re-checked my clips, and apparently there were problems with my Kelvin clips that made the weird offset, fixed it and here the 2nd round results.Suggesting to edit the 1st post's title, add the words "Mastech MS5308", hopefully these owners can share theirs as well here.

author: jpb
author_rank: Super Contributor
timestamp: March 21, 2016, 07:47:48 pm
content: Quote from: Carrington on March 21, 2016, 05:21:54 amI've not really looked into the claimed specs of the DE-5000 - just read one or two reviews when I bought mine cheap from Japan on e-bay.But thinking about it, without full kelvin measurement (and I've not even used the guard) I'm not surprised it has trouble. Trying to measure the inductance of 1cm or so of wire by calibrating out the variable inductance of a few cm of wire is probably rather optimistic.Better results might be obtained by making a solid jig of some sort or using coax with the guard. Your post has inspired me to experiment a little if I get time at the weekend.

author: Carrington
author_rank: Super Contributor
timestamp: March 22, 2016, 08:26:29 am
content: Their last reply:QuoteWell, it is true, for some LCRs you have to specify manually even the probe cable length.But, I think that enough is enough. I will not continue wasting my time with DER. No more drama.I answered using the photographs made by "jpb". Does anyone dare to guess what will be their reply?And when they say: "From your photos today, I still did not see it." They are referring to this test:https://www.eevblog.com/forum/testgear/strange-behaviour-with-my-de-5000/msg899473/#msg899473What can I say? I already knew that this would happen.However, I didn't expect any reply, so I'm surprised...I didn't do all this for my own interest, I only wanted to make it known.I hope that everyone will do the same after of detect something wrong on a instrument, especially if it doesn't care to the manufacturer.In this way, maybe we will invest our money in the right product, and all these rascals do not laugh on us.If this bug (or whatever) is not a problem for you, perfect, but now, you know it a bit more.They will continue making crap, without looking back. But as I did with OWON, I say:Fool me once, shame on you. Fool me twice, shame on me. (Anaxágoras)So goodbye forever, DER.

author: Carrington
author_rank: Super Contributor
timestamp: March 22, 2016, 08:32:35 am
content: Quote from: BravoV on March 21, 2016, 12:05:01 pmSo, was that!Quote from: BravoV on March 21, 2016, 12:05:01 pmBut the subject title will be very long. Any idea to summarize it a bit?

author: Carrington
author_rank: Super Contributor
timestamp: March 22, 2016, 08:36:07 am
content: Quote from: jpb on March 21, 2016, 07:47:48 pmPerfect! Go ahead!

author: The Electrician
author_rank: Frequent Contributor
timestamp: March 23, 2016, 08:43:47 pm
content: The results I reported in reply #31 were made using the built-in double-blade contacts, rather than any "Kelvin" clips or other leads. Has anyone else made the measurement on a 1 ohm resistor this way?

author: Macbeth
author_rank: Super Contributor
timestamp: March 23, 2016, 10:06:10 pm
content: Maybe I am missing something here, but surely OP is measuring a circuit and not a component. If I wanted to measure a 1 ohm resistor I would choose the R mode not the L mode? If he wants to measure the L of a piece of wire, then fine - it appears to do what it says on the tin.

author: mos6502
author_rank: Frequent Contributor
timestamp: March 23, 2016, 10:43:05 pm
content: Quote from: Macbeth on March 23, 2016, 10:06:10 pmNo, because any component isn't really a component in real life, but a circuit. That's why we have things likeequivalent circuitsfor capacitors and inductors. You have ESL, ESR, parasitic capacitance, etc.The meter should not show a change in inductance just because some ESR is added.

author: Macbeth
author_rank: Super Contributor
timestamp: March 23, 2016, 11:23:15 pm
content: I will have to do some testing with my DE-5000 tomorrow. I've got TL-21 and TL-22 and I will use this as an opportunity to knock up some proper Kelvin leads too.I should have some normal through hole 1 ohm resistors and hopefully some 0805 too. It seems the problem doesn't manifest at over 2 ohm?

author: BravoV
author_rank: Super Contributor
timestamp: March 24, 2016, 05:38:10 am
content: Quote from: Carrington on March 22, 2016, 08:32:35 amHow bout deleting the duplicate word "DE-5000" ?Old -> "Your DER DE-5000 or IET DE-5000, DE-6000 has this strange behaviour?"New -> "Your DER/IET DE-5000, DE-6000, MS5308 has this strange behaviour?

author: Carrington
author_rank: Super Contributor
timestamp: March 27, 2016, 04:54:32 pm
content: Quote from: BravoV on March 24, 2016, 05:38:10 amTo me is okay.I add a link to the chipsets datasheet:http://www.cyrustek.com.tw/spec/ES51920.pdf

author: edavid
author_rank: Super Contributor
timestamp: March 27, 2016, 05:29:34 pm
content: Quote from: Carrington on March 22, 2016, 08:32:35 amHow about forgetting the jokey title and making it "DE-5000, DE-6000, MS5308 can't measure 1 ohm resistor"?I'm not surprised that DER-EE couldn't understand your bug report, I had trouble myself

author: Carrington
author_rank: Super Contributor
timestamp: March 27, 2016, 05:36:01 pm
content: Quote from: edavid on March 27, 2016, 05:29:34 pmQuote from: edavid on March 27, 2016, 05:29:34 pm

author: Carrington
author_rank: Super Contributor
timestamp: March 27, 2016, 05:43:22 pm
content: @ edavid: Please read a bit, before post anything.

author: edavid
author_rank: Super Contributor
timestamp: March 27, 2016, 06:39:58 pm
content: Quote from: Carrington on March 27, 2016, 05:43:22 pmThat doesn't help

author: Carrington
author_rank: Super Contributor
timestamp: March 27, 2016, 07:11:28 pm
content: Quote from: edavid on March 27, 2016, 06:39:58 pmOk, in such case, have fun looking all the pretty pictures.

author: jarvis
author_rank: Contributor
timestamp: March 29, 2016, 06:53:39 am
content: Quote from: BravoV on March 21, 2016, 12:05:01 pmFrom your photo post, what is the wired offset you mentioned ?

author: BravoV
author_rank: Super Contributor
timestamp: March 30, 2016, 03:02:41 am
content: Quote from: jarvis on March 29, 2016, 06:53:39 amJust watch and compare my two measurements photos in this thread, both were calibrated. The 1st one shorted had an offset, I'm not sure what was causing that, but I guess it was fixed when there was a dangling soldering just holding few strands of wires inside the kelvin adapters and also they're so wiggly, once fixed the offset is gone.

author: jpb
author_rank: Super Contributor
timestamp: April 05, 2016, 07:53:32 pm
content: I've not got around to experimenting with jigs but to put something positive in for the DE-5000 I've just received some Russian mica capacitors and thought I'd show the measurements which are well within the specs.I'll need to post in several goes to keep within the 2k limit.

author: jpb
author_rank: Super Contributor
timestamp: April 05, 2016, 07:54:52 pm
content: C = 225 pF.

author: jpb
author_rank: Super Contributor
timestamp: April 05, 2016, 07:56:07 pm
content: 8000 pF = 8 nF example 1.

author: jpb
author_rank: Super Contributor
timestamp: April 05, 2016, 07:59:41 pm
content: 8 nF example 2.I have to wait 60 seconds now - to post again.

author: jpb
author_rank: Super Contributor
timestamp: April 05, 2016, 08:00:56 pm
content: Finally 100 nF (0.1 uF) or 100000 pF