Best CHEAP LCR meter for small capacitors and inductors? - Page 1
Forum section: electronics / testgear

author: ranchero
author_rank: Contributor
timestamp: November 22, 2022, 05:24:35 am
content: I periodically need to measure small capacitors (under 20pF, sometimes under 5pf) and small inductors (under 150NH).I currently have DE-5000 which has 100kHz range and should theoretically measure these small L and C just fine. But readings on these small L and C are very unstable even though I'm using TL-21 adapter with very short leads (like 4cm).Since it's more like a hobby I can't justify purchasing real good LCR meter (like PM6304).Do you guys think any less expensive LCR meter (let's say, under $200) will do any better than DE-5000? I would be totally happy with 10%-15% tolerance on these small L and C.Funny fact - every review on Youtube shows tests of electrolytic capacitors and big inductors, which almost any rectangular box with gauge on it able to measure, but never - very small values.Question#2 - what would be best setup to measure small SMD L and C (like 0402, 0603)? Currently I'm using small board with 2 pins, just soldering SMD elements to the board for measuring.

author: tautech
author_rank: Super Contributor
timestamp: November 22, 2022, 07:08:09 am
content: What's cheap ?Splash out on a pair of decent smart tweezers and never look back.See here:https://www.eevblog.com/forum/projects/smart-tweezers/

author: 2N3055
author_rank: Super Contributor
timestamp: November 22, 2022, 08:20:55 am
content: under $200 ?No, you cannot get better LCR than DE-5000 for that money.But your problem is not the meter. Such small capacities are measured by using mechanically stable measurement adapters and 4wire setup. Tl-21 is not stable enough for this. Such adapters can be very expensive to buy...Other option to measure small L/C is a VNA. You would also need a measurement fixture for that...Also what Tautech said, some tweezers (quality ones, that cost 200-300€) are much better at measuring small L/C because there are no cables and is more mechanically compact setup.Measuring such small values is all about dealing with parasitics in measurement setup.

author: ranchero
author_rank: Contributor
timestamp: November 22, 2022, 10:31:24 am
content: Smart Tweezers only have 10kHz frequency max, specs say that they will measure inductance from 0.5uH which is useless for me.What if I will create fixture which will fit directly into DE-5000 slots, with little board on top, and solder SMD part directly to that board? Virtually - no wires.Will it make measurements any more stable? Actually, stable readings even more important for me than actual values (but actual values would be nice of course).

author: coromonadalix
author_rank: Super Contributor
timestamp: November 22, 2022, 10:48:51 am
content: your "cheapest" will be the avr component tester project here loll

author: egonotto
author_rank: Super Contributor
timestamp: November 22, 2022, 11:00:54 am
content: Hello,is an indirect measurement via the resonant frequency with L or C connected in parallel an alternative?Best regardsegonotto

author: ranchero
author_rank: Contributor
timestamp: November 22, 2022, 11:15:40 am
content: I'm trying to keep as simple as possible and avoid indirect measurement.Basically - I have board with damaged/missing SMD L or C and no documentation available whatsoever. And I have good board, I can temporary borrow corresponding L or C from it to measure values.The other problem I'm running into - when buying small inductors on Aliexpress sellers very often (in fact - almost always) just send random values, like 500NH instead of 100NH, 220NH instead of 130NH and so on.Inconsistent readings don't help to solve this puzzle at all.

author: skander36
author_rank: Frequent Contributor
timestamp: November 22, 2022, 11:37:23 am
content: A cheap alternative LC meter that claim to measure up to 500 KHz is MLC500.But for SMD you still need a good fixture.https://www.amazon.com/Digital-Precision-Automatic-Inductance-Capacitance/dp/B083SG8TYVOn Aliexpress even more cheap - 50 $

author: 2N3055
author_rank: Super Contributor
timestamp: November 22, 2022, 11:44:19 am
content: Quote from: ranchero on November 22, 2022, 10:31:24 amTweezers I have go to 100kHz.Actually that fixture is exactly what I wanted to say. Make a fixture that will be mechanically stable and will sit on top of meter. Than calibrate with fixture in place and you will get way better results.

author: ranchero
author_rank: Contributor
timestamp: November 22, 2022, 11:46:16 am
content: Quote from: skander36 on November 22, 2022, 11:37:23 amHmm...Anyone tried it in person? Looks like "too good to be true". Need to do some research on this.Update - found review on this - not very promising. Impossible to believe that $60 tester can do what $300 testers can't.

author: ranchero
author_rank: Contributor
timestamp: November 22, 2022, 11:59:35 am
content: Quote from: 2N3055 on November 22, 2022, 11:44:19 amModel?

author: kripton2035
author_rank: Super Contributor
timestamp: November 22, 2022, 01:00:23 pm
content: may be you can build this yourself, at least for measuring small caps ?https://www.romanblack.com/onesec/CapMeter.htm

author: mcovington
author_rank: Regular Contributor
timestamp: November 22, 2022, 01:11:22 pm
content: NH? Nanohenries? That is a TINY inductance. Do you mean millihenries or microhenries?

author: 2N3055
author_rank: Super Contributor
timestamp: November 22, 2022, 01:56:06 pm
content: Quote from: ranchero on November 22, 2022, 11:59:35 amLCR Research LCR Pro1 Plus Smart LCR Tweezers

author: ledtester
author_rank: Super Contributor
timestamp: November 22, 2022, 02:17:59 pm
content: Quote from: skander36 on November 22, 2022, 11:37:23 amDoes anyone know how this meter works?From the odd test frequencies I am guessing it is a clone of the AADE LC IIB meter:https://sites.google.com/site/vk3bhr/home/lcm1You can find several forum threads here on it, including this one:https://www.eevblog.com/forum/rf-microwave/suitable-alternative-to-the-aade-lc-meter/

author: mawyatt
author_rank: Super Contributor
timestamp: November 22, 2022, 02:25:39 pm
content: What may work with your DE-5000, and give you a more stable and repeatable results is a SMD fixture for use with a proper lab type LCR meter like shown. You can get name brand fixtures for ~$200 (Tonghui) or no name ones like shown for ~$100.To connect this to the DE-5000 you'll need to prepare a BNC cable adapter that uses a TL-21 modified with 4 BNC cables to attach to the SMD fixture. We were going to do this but never got around to it since we now have 2 lab grade LCR meters.Should fit within your $200 budget.If you need these types of measurements often, then seriously consider a lab grade LCR meter with necessary fixtures. For example the Tonghui TH2830 (only goes to 100KHz tho) supports measurements in the pF and nH range with good results. We have some some in-house references SMD caps like Venkel COG 4.7pF and 10pF that show repeatability better than 0.01pF with this instrument & fixture (a Hioki IN3536 shows similar results over a broader frequency range).Edit: Also consider the TL-22 Tweezers for the DE-5000.Best,

author: 2N3055
author_rank: Super Contributor
timestamp: November 22, 2022, 02:31:14 pm
content: I still think that measuring in low nH / pF range would be best done with cheap VNA and proper fixture...

author: nctnico
author_rank: Super Contributor
timestamp: November 22, 2022, 02:59:58 pm
content: Quote from: ranchero on November 22, 2022, 05:24:35 amThere is this XJW01 LCR bridge that is pretty cheap and does proper 4 wire measurements. In my experience it will measure small capacitors just fine. I have not tried inductors. Ideally you'd use an SMD test fixture but that alone will set you back around $200. But a board will also work as a test fixture. In such a setup I'd solder SMA connectors to the board and use short SMA to BNC cables to connect to the XJW01. I don't know what kind of board you are using now but if you have not done that already, you could design one yourself. A double sided board with traces that keep the measurement to be a 4-wire measurement as much as possible would be good and only costs a few dollars to order from JLCPCB, Seeed, etc.

author: fourfathom
author_rank: Super Contributor
timestamp: November 22, 2022, 03:15:18 pm
content: Quote from: mcovington on November 22, 2022, 01:11:22 pmYes it is, and we deal with nH inductors all the time in RF work, especially as the frequency gets above 10 MHz or so.

author: mawyatt
author_rank: Super Contributor
timestamp: November 22, 2022, 03:34:40 pm
content: Quote from: 2N3055 on November 22, 2022, 02:31:14 pmDepends on the frequency range of interest, a VNA is certainly the correct choice for higher frequencies.For example, if you consider the impedance of 2pF at 100KHz, that's ~796K ohm, a 50 ohm reference VNA will have a difficult time accurately resolving this high an impedance, whereas a quality LCR should work well. However, if we change to say 10MHz, then the impedance drops to ~7.96K, within the range of the VNA and pushing the frequency limits of the LCR. In between these overlapping frequency ranges it becomes a toss up which instrument is the better suited.Why most of us have a VNA and LCR meterBest,

author: mawyatt
author_rank: Super Contributor
timestamp: November 22, 2022, 03:58:13 pm
content: Quote from: nctnico on November 22, 2022, 02:59:58 pmThose XJW01 LCR bridge look interesting, but only show a max frequency of 7.8KHz. Looks like some old-school design with many discrete thru-hole components, but should be fun to play with. Believe the DE-5000 also uses a bridge concept but with a custom chip pair. We've compared the DE-5000 with our two lab grade LCR meters over a wide range of Cs, Rs and a few Ls, the results were indeed impressive for a handheld low-cost instrument!!Best,

author: nctnico
author_rank: Super Contributor
timestamp: November 22, 2022, 06:36:19 pm
content: I did some tests with my XJW01 but it's usefull range is from -say- 10pf or from 1uH. So not a fit for the requirements for the OP.

author: Vojtech
author_rank: Contributor
timestamp: November 22, 2022, 06:53:06 pm
content: Consider ET432, it has Kelvin clips, I am very satisfied with it.

author: mawyatt
author_rank: Super Contributor
timestamp: November 22, 2022, 08:20:15 pm
content: Just did a quick check with the DE-5000 measuring a 53mm length of solid #12 Cu wire, this should be ~41.7nH per calculations and we measured 43nH (100KHz) with TL-21 fixture. For ACR we get 0.002 ohms tho, and this is calculated as 281u ohms, with DMM6500 we get 271.7u ohms, so obviously below the DE-5000 resolution.Also measured a 17.5 turn open wire inductor at 292nH (100KHz) with DE-5000 & TL-21, TH2830 with 292.737nH and IM3536 with 292.17nH.BTW the core DE-5000 is a 4 wire Kelvin Type System, the TL-21 Fixture brings the each 2 Force/Sense wire sets to the Bottom of each Alligator Clip as shown below with the 2 wire inductors. This is a left over from a TL-21 we modified some time ago for a true Kelvin setup with long Kelvin leads and clips.Anyway, just some measurement and hope this helps.Best,

author: ranchero
author_rank: Contributor
timestamp: November 22, 2022, 10:10:58 pm
content: Just to clarify - I do have TL-22 tweezers, from my experience it doesn't do any better on small L and C comparing to TL-21. I do have Kelvin clip and I've seen video of modification to use them with DE-5000, just didn't have a chance to try it myself.So far - reading this thread - I think, as few people suggested - I need to make small fixture without wires and try to use it directly on DE-5000.Other question - is it normal to do calibration on DE-5000 every time you turn it on? It seems that values do change a bit after calibration.Quote from: 2N3055 on November 22, 2022, 01:56:06 pmSpecs are very promising. $300 - a bit more expensive than I would like them to be...But I will think about them, thank you.Quote from: Vojtech on November 22, 2022, 06:53:06 pmHave you tried it with very small SMD L and C? Would you share your setup and results?

author: Martin72
author_rank: Super Contributor
timestamp: November 22, 2022, 11:56:56 pm
content: QuoteDepends on how accurate you want to have the measures.Ambient temperature/humidity are changing plus warmup of the meter itself.

author: thm_w
author_rank: Super Contributor
timestamp: November 23, 2022, 12:47:50 am
content: If you didn't already have the DE-5000 then I would say consider these:https://shannontweezers.top/

author: tautech
author_rank: Super Contributor
timestamp: November 23, 2022, 01:06:20 am
content: Quote from: thm_w on November 23, 2022, 12:47:50 amWhy ?To be properly equipped you need both.

author: thm_w
author_rank: Super Contributor
timestamp: November 23, 2022, 01:47:06 am
content: Quote from: tautech on November 23, 2022, 01:06:20 amJust because its not entirely clear what OP is doing.If its in circuit measurement then the tweezers are great to have. If its measuring a part, very precisely, prior to install, then maybe the mentioned SMD jig with a DE-5000 would be more repeatable.

author: ranchero
author_rank: Contributor
timestamp: November 23, 2022, 02:15:41 am
content: Quote from: thm_w on November 23, 2022, 01:47:06 amI don't think it's even possible to measure such small values correctly in-circuit. So - I always remove them. The tweezers you've recommended only go up to 10kHz, so they will not measure small inductors.

author: pqass
author_rank: Super Contributor
timestamp: November 23, 2022, 02:35:16 am
content: I know you're probably not looking for a DIY LC meter now, but in case you've hit a wall, consider the LC-meter project below (or at least the oscillator part).I'm currently implementing the LC+LM311 oscillator [on perf-board] just to validate the approach before committing further. See attachment. I'm using a bread-boarded  frequency counter (which I happen to have handy) but any bench counter will do. Also, I've removed the need for relays in my version; replaced with a DPDT and BJT.See Part 1 of the video at10:28 for the theory of operation. (https://youtu.be/KhJiE4gL5T4?t=628)16:26 for the six formulas involved (just one frame athttps://youtu.be/KhJiE4gL5T4?t=986)17:54 for the algorithm on how to determine C-DUT or L-DUT (https://youtu.be/KhJiE4gL5T4?t=1074)To summarize:(a) first measure the freq. without any C-DUT attached,(b) then turn on calibration cap BJT (still no C-DUT),(c) then, attach a C-DUT (w/o cal cap) and measure freq.; use formula 5 to determine value.OR attach L-DUT (w/o cal cap) and measure freq.; use formula 6 to determine value.Calibration steps (a) and (b) only needed every once in a while.I've successfully measured down to 16pf (all I had) just using manual recording of the frequencies with/without DUT and calibration cap into a spreadsheet. Measuring inductors yields values close to whats printed, although, in the 10s of uH to 100mH; I don't have any nH inductors. The chosen L+C values has problems with >1uF C-DUTs so I'll be exploring other combinations to determine ranges.FYI: I'm just a hobbyist (no EE) and as such, am not (yet) knowledgeable on the intricacies of those fancy HP LCR meters on eBay. But this appears to fit my C and L measurement needs and may be worthwhile for you. Also, in case you're wondering, the reciprocal frequency counter on the b-b [74HC4020+74HC74+ATTINY84] is based onwww.instructables.com/High-Resolution-Frequency-Counter/(good to 7 digits) but I've done a major rewrite of the software.Original LC meter project links:Hackaday IO:https://hackaday.io/project/178081-build-an-lc-meterGithub:https://github.com/coreWeaver/LC-MeterLook for parts 1 thru 5:https://www.youtube.com/channel/UCSwxZFW1XBvgM92nI7XMwSA/videosMeasuring Femto Farads:

author: ranchero
author_rank: Contributor
timestamp: November 23, 2022, 03:03:10 am
content: I would love to participate in this project, but unfortunately I'm not in the position when I can spend time on it.

author: mawyatt
author_rank: Super Contributor
timestamp: November 23, 2022, 02:19:23 pm
content: Generally small inductance is more difficult to measure than small capacitance. One fundamental reason is inductance is highly dependent on length, whereas capacitance is inversely so, and at a moderate frequency a small capacitance has a relative high impedance whereas a small inductor is low impedance.As you move up in frequency the capacitive reactance drops and the inductance reactance increases, however for small L like 100nH is only ~ 0.063 ohms at 100KHz and a small capacitance of 100pF is ~ 15.9K ohms. So getting a good "zero" reference for the L is difficult, but relatively easy for C.As mentioned by 2N3055 a VNA is maybe a better choice is some cases, and for small inductances this is the case!! The usual VNA is a low 50 ohm instrument that allows moving the "reference plane" up to the DUT fixture, thus removing the setup and fixture "length", LCR meters don't do this, although some of the lab types do have a "cable length" option which compensates for the test cable phase shift.Measuring small capacitance ~100pF can be achieved with even a DMM capacitive measurement in a pinch, one must carefully null out the residual and keep the cables fixed in place (tapped to the workbench for example). Heck, Dave even showed how to measure Inductance with a DMM in his April 1 VideoBest,

author: thm_w
author_rank: Super Contributor
timestamp: November 23, 2022, 11:03:00 pm
content: Quote from: ranchero on November 23, 2022, 02:15:41 amIt just depends on the circuit in question, there is no blanket answer. If you know a specific inductor has nothing in parallel with it, then it will measure OK.Those tweezers can measure a 0R 0603 at ~5nH in circuit. BUT thats very much in the noise, and I would not consider it repeatable at all. Which is where a jig is better (consistent distance, pressure, etc.).

author: Vojtech
author_rank: Contributor
timestamp: November 24, 2022, 08:24:51 am
content: As Mawyatt mentioned, measurement of nH at 100 kHz needs mOhm resolution, so 4 wires Kelvin is a must. A quick test of ET432 with shorted inputs at 100 kHz - resolution is down to pH, the result is stable to some hundreds of pH. Capacitance measurement at 100 kHz with open input – offset is some tenths of pF (can be nulled out), the resolution is 1 fF, the result is stable to 1 fF. Of course, the moving of cables changes measured capacitance with some tenths of pF. I have no etalon of low caps or inductors, so I am not able to verify absolute accuracy. Still, its meaning is questionable – with such low values parasitics in real PCBs play a significant role so absolute accuracy is questionable here. I think ET432 is better than DE-5000 with still an acceptable price.

author: iMo
author_rank: Super Contributor
timestamp: November 24, 2022, 08:38:04 am
content: Quote from: pqass on November 23, 2022, 02:35:16 amI built that famous LC meter myself some 20y back, wrote my own fw at that time. It works great.. The lowest C and L values are measured at something like 500-700kHz frequency.PS: I would definitely use a relay with the 1n reference capacitor (not the npn transistor as you do)..PPS: And do not forget the "Null" button where you measure the L or C of the probe wires before the actual measurement

author: ranchero
author_rank: Contributor
timestamp: November 24, 2022, 09:37:51 am
content: Just ordered ET432 with Kelvin clip while Black Friday sale is going on (about $130US with all discounts). Will compare with ET-5000 when I will receive it.

author: hgjdwx
author_rank: Regular Contributor
timestamp: November 24, 2022, 02:41:39 pm
content: LQ-9101 is better than DE-5000

author: ledtester
author_rank: Super Contributor
timestamp: November 24, 2022, 02:42:50 pm
content: About the LM311-based LC meter... I found another design which uses a 74HCU04D instead of the LM311:https://www.pcbway.com/project/shareproject/LC_meter_of_using_the_franclin_oscillator_9b1ebd81.htmlThe description there mentions a "Dr. Hegewald" and I was able to find this discrete LC-tank exciter circuit credited to him:https://home.kpn.nl/a.van.waarde/lc.htm

author: mawyatt
author_rank: Super Contributor
timestamp: November 24, 2022, 04:33:30 pm
content: Here's a post on using a cheap SMD Fixture connected to the DE-5000, well more kludged that "connected"Please note the entire thread and the earlier reference SMD 4.7pF cap used with the two SMD Fixtures and the Lab Grade LCR Meters for measurements.https://www.eevblog.com/forum/testgear/cheap-smd-lcr-fixture-the-good-bad-and-ugly!/Best and Happy Thanksgiving!!

author: mawyatt
author_rank: Super Contributor
timestamp: November 24, 2022, 04:48:54 pm
content: Quote from: hgjdwx on November 24, 2022, 02:41:39 pmLooks interesting but apparently only supports 10KHz, DE-5000 supports 100KHz!! This is an often overlooked specification, and the higher frequency range instruments need to employ more sophisticated circuits and algorithms, and why above ~100KHz the LCR meter price rises exponentially!!Believe the DE-5000 utilizes a unique custom chip set that employs a high resolution SD ADC as well, also believe this is the same chip set utilized in the popular ET432 since both have identical Cal procedures (30 counts) & frequency ranges, and very similar specs. Soon we'll have a direct comparison of these two, as ranchero has both availableBest and Happy Thanksgiving

author: thm_w
author_rank: Super Contributor
timestamp: November 25, 2022, 12:33:30 am
content: Quote from: Vojtech on November 24, 2022, 08:24:51 amYeah that looks quite good.Wonder if ET430 can be hacked to ET432. ET433 seems like it might have different hardware inside.

author: balnazzar
author_rank: Frequent Contributor
timestamp: November 25, 2022, 01:59:55 am
content: Quote from: egonotto on November 22, 2022, 11:00:54 amBeware of indirect measurement if you are not super-experienced. Parasitic stuff in the components will make you calculations' result quite unreliable.

author: mawyatt
author_rank: Super Contributor
timestamp: November 26, 2022, 04:00:58 pm
content: This may be the chip set utilized in the DE-5000 and ET432. The chip set appears to incorporate bridge approach and contains most of the necessary components, including high res ADC (likely high bit count Sigma-Delta type), to realize a quality LCR result.Believe this chip set is the main reason these handheld LCR meters perform and yet are reasonably priced, classic example of custom chips improving performance and reducing costs.....integration ruleshttp://www.cyrustek.com.tw/wp-content/uploads/ES51920.pdfBest,

author: Vojtech
author_rank: Contributor
timestamp: November 27, 2022, 06:41:26 pm
content: ET432 has a higher resolution and better accuracy than mentioned chip, so different hardware has to be used.To thm_w : ET432 comes with Kelvin clips, ET430 does not.

author: TimFox
author_rank: Super Contributor
timestamp: November 27, 2022, 07:35:35 pm
content: For a while, IET (successor to General Radio) offered their DE-6000, which appears to be a rebadged DER meter with tighter specs.It is no longer available from IET, and was in the same package as the DE-5000, but a nicer color.https://www.ietlabs.com/pdf/Datasheets/DE-6000.pdfIET's data sheet for their (also discontinued) DE-5000 (in yellow):https://www.ietlabs.com/pdf/Datasheets/DE_5000.pdfSlightly better specs on the more expensive 6000: at 1 kHz and the 200 nF FS range, the 6000 spec'ed 0.2% and 2 digits, while the 5000 was 0.3% and two digits.When it was available, I recommended the IET DE-6000 to a colleague because it was available with a traceable calibration, which his job required.

author: MathWizard
author_rank: Super Contributor
timestamp: January 19, 2023, 05:01:58 pm
content: LCR tweezers sound nice. But yeah if the good ones are starting around $300, I'm in no rush.I have a cheap Mastech LCR metter but it has Kelvin probes. But it's not the best at measuring large caps like +1000uF. I can't remember it's rating, but some times it seems to do it just fine, but other times, it just never gets a reading, even at lower frequencies too.I don't really need another LCR meter, but I would like a better 1, but I'd love the self-contained chopstick ones too. The case of the mastech meter is really big, but it's mostly hollow. But well it does have a nice huge screen tho.

author: tautech
author_rank: Super Contributor
timestamp: January 19, 2023, 06:51:57 pm
content: Quote from: MathWizard on January 19, 2023, 05:01:58 pmMaybe you missed the development of these at half the cost of the big boys:https://www.eevblog.com/forum/testgear/design-a-new-precision-lcr-tweezers/

author: mawyatt
author_rank: Super Contributor
timestamp: January 19, 2023, 08:29:20 pm
content: As mentioned earlier, this setup for SMD with the DE-5000, a modified TL-21, and a cheap SMD fixture works extremely well, and is highly repeatable. We get results that agree quite well with our IM3536 & TH2830 lab grade Bench LCR Meters. The DE-5000 does have True 4 wire Kelvin type capability, with separate Guard Ground which are utilized in this setup, and a likely reason for the performance .Highly recommend setup for those interested in quality SMD measurements, quick, accurate (compared to lab bench quality LCR meters), repeatable, that we prefer over tweezers.Edit: BTW the reading here was from a quality Venkel 0603 4.7pF COG cap that measured 4.71pF on 12/23/22. Also, the modified TL-21 and SMD fixture were connected, plugged into the DE-5000, and the DE-5000 wasn't even recalibrated for this quick measurementOf course YMMV.Best,

author: vinlove
author_rank: Frequent Contributor
timestamp: January 20, 2023, 11:45:06 pm
content: I bought this Chinese LCR meter from eBay about 10 years ago. It is still working OK. It was cheap, but now I cannot remember exactly how much I paid for it.https://www.amazon.co.uk/dp/B096MJZ6ZL/ref=sspa_dk_detail_7?psc=1&pd_rd_i=B096MJZ6ZL&pd_rd_w=8mC9s&content-id=amzn1.sym.15c0cc83-c6c5-4d44-aa3d-0de17a9f3682&pf_rd_p=15c0cc83-c6c5-4d44-aa3d-0de17a9f3682&pf_rd_r=SY4C0ES1R53NC7H64422&pd_rd_wg=qeS0x&pd_rd_r=8fe0b2d6-72d5-46f4-a213-8e0fb633ee2a&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw

author: baldurn
author_rank: Regular Contributor
timestamp: January 21, 2023, 02:18:57 pm
content: What does a fixture for measuring on a VNA look like? Anyone have a link to some products or description of the procedure?

author: rsjsouza
author_rank: Super Contributor
timestamp: January 21, 2023, 11:57:49 pm
content: I regularly use my Reed 5001 with an adapted Keysight U1782B tweezer and it yields quite reasonable single-digit picofarads and 0.1mH measurements - all using relative mode (which the instrument calls "calibration"). However, a standing fixture like the one showed above is extremely stable for repeated measurements, especially when categorizing tens or hundreds of parts.https://www.keysight.com/us/en/product/U1782B/smd-tweezer.html

author: jimjam
author_rank: Regular Contributor
timestamp: February 10, 2023, 11:50:46 pm
content: Quote from: ranchero on November 24, 2022, 09:37:51 amHave you received it? Curious to hear your comparison against DE-5000

author: precaud
author_rank: Frequent Contributor
timestamp: February 11, 2023, 02:20:32 pm
content: Quote from: nctnico on November 22, 2022, 06:36:19 pmThe XJW01 needs to be calibrated at the BNC terminals, not at the end of the tweezer cable. Otherise the Open/Short routines can't and won't work, and accuracy at the extremes suffers.My XJW is fine for small C's and L's.

author: mawyatt
author_rank: Super Contributor
timestamp: February 11, 2023, 03:39:02 pm
content: Quote from: precaud on February 11, 2023, 02:20:32 pmWe don't have a XJW01 but this statement doesn't make sense??The test leads/tweezer are "part of the DUT measurement", whatever they are. The only way to remove the test lead measurement effects is to include them in the Open/Short calibration routines.Our lab LCR meters the Tonghui TH2830 and the expensive ($5K) Hioki IM3536 require test leads/fixtures to be included in the Open/Short calibration, in fact the Hioki requires the test lead length as a parameter.I'm sure if do a simple test of a well known component such as a 10~100pF capacitor and 1~10 ohm resistor with the instrument calibration "at the BNC terminals" vs. "with the test leads attached" you'll see the accurate results favor the test leads included calibration.Best,

author: precaud
author_rank: Frequent Contributor
timestamp: February 11, 2023, 06:41:48 pm
content: Quote from: mawyatt on February 11, 2023, 03:39:02 pmYes, but the calibration procedure and the Open/Short compensation math are not the same. If you cal the unit at the BNC's, then the Open/Short math can properly do what it is designed to do; counteract for the impedance of the fixtures/leads.If you cal the unit with a set of leads, then the Open/Short correction is effectively bypassed.Try it.

author: mawyatt
author_rank: Super Contributor
timestamp: February 11, 2023, 07:42:37 pm
content: Quote from: precaud on February 11, 2023, 06:41:48 pmAs mentioned we don't have a XJW01, so can't give it a try!!Edit: Rereading this, does the XJW01 have a separate Calibration to the instrument BNCs, then another Open/Short Calibration/Correction for the test leads/fixture effects? If true then we need to reword the stuff within the"" quotesbelow."If you just cal to the instrument BNC connectors, then how is one expecting an accurate DUT result with an external fixture and/or test leads? How does the instrument know what the external leads/fixture represent? Not sure how this "math" works even with perfect Kelvin leads regarding capacitive/inductive measures where phase shift comes into play?Does the instrument not allow cal with external leads/fixture (does it sense this somehow?), and how does it establish a Short reading, as a short between HC and LC, or HC to HP then to LC to LP? Curious as to how this and the cal math works?"The DE-5000 we have does allow Open/Short calibration with external fixture/leads at the fixture/leads, not at the instrument interface.Anyway, interested to understand how this calibration & math works?Best,

author: precaud
author_rank: Frequent Contributor
timestamp: February 11, 2023, 08:16:12 pm
content: Open/Short compensation is NOT calibration.It compensates for the affects of test fixtures and leads.HP's Impedance Masurement Handbooks discuss this in detail.

author: mawyatt
author_rank: Super Contributor
timestamp: February 11, 2023, 09:10:00 pm
content: Whatever you want to call it.The DE-5000 this is referred to as "CALibration", the TH2830 calls it "CORRection", Hioki calls is "ADJUSTMENT", suspect other LCR OEMs might call it Compensation!!So take your pickBest,

author: precaud
author_rank: Frequent Contributor
timestamp: February 12, 2023, 02:33:45 pm
content: Look at the underlying concepts instead of getting caught in the semantics.There are two of them, so best we use different words for them.If we can't agree on language, not much of a discussion is possible.I am using Calibration to refer to the adjustment of the machine to its stated accuracy at its connectors.I am using Compensation to refer to the procedure that extends that accuracy to the measurement point of a fixture or the end of test leads.They are not the same process. I doubt the internal math is the same for them, either.All I'm saying is, using the words as defined above, don't CalibrateanyLCR meter using test leads.Calibrate it at its connection terminals. and then use Open/Short Compensation (or OSL if available) for whatever leads or fixture used.This is just common sense.

author: mawyatt
author_rank: Super Contributor
timestamp: February 12, 2023, 04:21:34 pm
content: Interesting, even Hackaday refers to your XJW01 "Calibration" with the Kelvin leads attached, see snip below.Calibratethe meterIt's time for calibration. It's not a super-obvious procedure, but it is fairly easy.First, measure the included resistors as accurately as possible. There should be a 40R, 1K, 3K, 9K, 10K and 100K resistors. Go nuts with 50 power line cycles, averaging, 6,5 digits, 4-wire measurements and all that. We will use the measurements you've done to calibrate the meter to.Once you've measured the resistors to an accurately enough degree, it's time to start the calibration procedure:Turn the unit onPerform ashort test lead calibration. Clamp theKelvin clipstogether and press the "Zero" buttonPerform anopen test lead calibration. Disconnect the kelvin clips and press the "Zero" buttonHold down MENU for approximately 3 seconds, this will bring up the options menuPress RNG to enter calibration mode, the display should now show "Z0"For the calibration, we will adjust the instrument to exactly match the previously measured resistor values (as well as some other parameters). Use the CLR (up) and SP/ESR buttons (down) to adjust the values. Use FREQ to go to the next parameter and QTY to go back.Set the values of the different parameters as follows:Step Target Value NotesZ0 Z=0 Short the Kelvin clipsZ1 Z=0 Short the Kelvin clipsZ2 Z=0 Short the Kelvin clipsR1 40R resistorConnect the resistor and try to match what you previously measured with your multimeterR1X θ=0 Leave the resistor connectedR2 1K resistorConnect the resistor and try to match what you previously measured with your multimeterR2X θ=0 Leave the resistor connectedR3 10K resistor Connect the resistor and try to match what you previously measured with your multimeterR3X 0 pF Leave the resistor connectedR4 100K resistorConnect the resistor and try to match what you previously measured with your multimeterR4b 100K resistorConnect the resistor and try to match what you previously measured with your multimeterR4X 0 pF Leave the resistor connectedG1 3K resistorConnect the resistor and try to match what you previously measured with your multimeterG1X 0 pfLeave the resistor connectedG2 9K resistorConnect the resistor and try to match what you previously measured with your multimeterG2b 9K resistorConnect the resistor and try to match what you previously measured with your multimeterG2X 0 pfLeave the resistor connectedPhX θ=0 Connect the 1K resistorAftercalibration, make sure to save your changes with the Hand/Auto button!https://hackaday.io/project/175641/instructionsNot trying to divert nor get into a useless argument as so often happens, nor play word games.Just curious how one does as you say "a Calibration to the Instrument BNC terminals". Since these instruments are 4 terminal measurements, how does one Calibrate such.How do you connect a reference resistor or capacitor (or reference short) directly to the 4 BNC terminals without some sort of cables/leads, or does the instrument have a "built-in" calibration means which includes input switching relays and Reference components inside the instrument?If one has a known set of Calibration cables/leads which are well known and characterized, I can see how these could be utilized with the external Reference components and the lead effects "backed out" to the BNC connectors, sort of like with a VNA.If this is true then I can see how one could do an Open/Short Compensation with whatever cables/leads or fixture that is attached to the 4 BNC instrument connectors and Compensate for such by means of mathematically removing these external effects.BTW we do agree with the basic HP terminology regarding LCR Calibration and such, but when the 2 lab grade instruments we posses utilize completely different terminology, as does the Handheld LCR meter, and all different as shown, then the term "LCR Calibration" becomes a much more broad coverage term.Our best guess to all this is the XJW01 establishes it's internal Calibration coefficients with the supplied Kelvin Clips by means of measuring various external reference components as shown in the Hackaday article, and does not mathematically remove these Kelvin clip effects to move back to the BNC terminals, please advise if this assumption is incorrect. Whereas a proper lab grade instrument utilizes a special "fixture" of know effects to establish a measurement reference plane at the BNC terminals at the instrument Calibration and Verification (which requires such with lab grade certified reference fixture and components), and then the Calibration/Correction/Compensation/Normalization or whatever we call it, the Short and Open are performed with the intended usage cables/leads or fixture. The instrument will mathematically remove the effects of this Open/Short procedure, and in some cases will also take into account the effects of the measurement cable length.Anyway, not trying to get into a useless argument here, just trying to understand how this instrument achieves said results. If we had one of these XJW01 instruments then we would know how all this works, and with the relatively low cost might be worth acquiring just to learn somethingBest,

author: 2N3055
author_rank: Super Contributor
timestamp: February 12, 2023, 08:35:13 pm
content: I'm with Mike here..I look at impedance meter as I would to low frequency VNA.In VNA parlance calibration is, well, calibration and compensation of all (possible) parasitics out. Math behind it can be quite complicated as there are many possible math models the can be used. It establishes the scale and accuracy of measurements. And since it is very dependent on parasitics of interconnect and fixtures you use to measure DUT, you calibrate with fixture in place...With RCL meter open/short calibration actually calibrates zero and open (infinite impedance) values at end of fixture. It is calibration, maybe not full one but at least those two pins are established. Fact that LCR meter has internal adjustments of circuitry is internal to how hardware functions... If that doesn't work well, adjustments need to be made to device... So I would call that repair or adjustments in this context.This is how word calibration is usually used in this context.Metrology guys would tell you calibration is just a check what values your device measures when measuring reference values.... And no adjustment is included with that word...

author: precaud
author_rank: Frequent Contributor
timestamp: February 13, 2023, 02:32:52 pm
content: Quote from: mawyatt on February 12, 2023, 04:21:34 pmUsing 4-terminal standards with BNC's, like HP 16074A and others, that attach directly to the outputs, and are characterized at the BNC's. Your lab-grade LCR meters were undoubtedly calibrated that way. I'm pretty sure there have been threads about making DIY versions of the 16074A.If you don't have access to those (few do), then use the most-compact fixture you can find to calibrate the instrument.THEN, your Open/Short routines will more accurately compensate for other fixtures and leads.If you calibrate an instrument at the end of test leads, and then use a fixture, or shorter leads, the Open/Short vector math can not accurately correct for a negative impedance difference.Impedance via a VNA is not the same as 4-terminal balanced bridge.Again, I highly recommend the HP/Agilent Impedance Measurement Handbook. It doesn't matter what brand LCR meter you have, they all use the same basic technique developed by Henry Hall for General Radio decades ago.The procedure given for the XJW01 is for end-users using items supplied with the instrument. The instructions are fine except for directing users to use the supplied Kelvin clips. If you do that, then you will have increasing uncertainty/inaccuracy at the impedance extremes. Which is exactly the OP's concern.Think about what is going on in calibration versus compensation (no matter what words you choose for them) and it will become clear to you. Calibration stores internal offsets for known impedance values (typically zero and near-full-scale per range) mostly to correct for manufacturing tolerances. In the "old days" trimmer pots were adjusted for it. These are simple offets added or subtracted from the values that the A/D converters are delivering, and set the vector starting points. Open/Short compensation then "extends" these points to the end of your test leads, using vector (real & imaginary) math.In an ironic note, I borked my XJW01 yesterday by inadvertantly connecting a charged 'lytic to it. The LCR meter I use the most, an HP 4276A, is totally fine with charged caps and I sometimes forget that other meters aren't. Sigh.

author: scopeman
author_rank: Frequent Contributor
timestamp: March 02, 2023, 10:27:52 pm
content: You probably just blew the protection diodes. Usually the meter comes with spares. IIRC they are just 1N4148 MELF Diodes. Have fun taking it apart to replace them!SamW3OHM

author: precaud
author_rank: Frequent Contributor
timestamp: March 03, 2023, 01:41:15 am
content: Yes, it was an easy fix, easy to access, too.