1MHz or Greater LCR Meter? - Page 1
Forum section: electronics / testgear

author: AJ3G
author_rank: Regular Contributor
timestamp: November 27, 2019, 02:48:41 pm
content: All:Is anyone aware of a LCR meter which can measure L/C at a frequency of 1MHz or greater, which is reasonably priced? I have been using a AADE for years to conduct these types of measurements, but AADE is no longer.Rich

author: coromonadalix
author_rank: Super Contributor
timestamp: November 27, 2019, 03:34:49 pm
content: Define your reasonably priced, if you have done some search you already have an idea they wont be cheapyou have Fluke pm6306, hp 4284 and 4287 and up, never saw one under 700$ usd and they easily start around 1k $$

author: Frex
author_rank: Regular Contributor
timestamp: November 27, 2019, 03:46:57 pm
content: Hello,You ca do very good measurement R / L /C over a wide bandwidth (DC to 20MHz) usingthe Analog discovery. It's a very good , accurate and cheap solution IMHO.You can see here :Frex

author: AJ3G
author_rank: Regular Contributor
timestamp: November 27, 2019, 05:30:02 pm
content: Thank you both for your reply’s.Yes, I have looked at those. I was hopping to stay at 1K or less in price. Ideally, I was hoping someone had come up with something like AADE produced before the owner passed away. It lasted me for years, and was good enough to do the job. I would prefer something handheld like the AADE, but after review I am just not seeing that type of instrument available anywhere.I am not objectionable to buying something used, or even broken and fixing it. I guess what I was hoping to uncover was a more compact alternative. If that is not possible, I need to reliably measure L/C at higher frequency’s, thus I am willing to look at options which may be “boat anchors” so to speak.Frex - Let me have a look and see what analog discovery is all about. I have never heard of the product, thanks for bringing it to my attention.Rich

author: edavid
author_rank: Super Contributor
timestamp: November 27, 2019, 05:43:26 pm
content: OP, your question is confusing. The AADE meter was not a true LCR meter (not phase sensitive), and it also did not work in the 1MHz range.If you want a simple oscillator/frequency counter LC meter like the AADE, you can buy one of the Chinese products like the "LC200A" or the "secohmmeter" cheaply on eBay. They will work just as well.Or if you want a true LCR meter, and can live with a 100kHz maximum measuring frequency, you can buy a DER-EE DE-5000 for about $100. (This is a much, much better instrument than the AADE meter.)But if you really want to make accurate LCR measurements at 1MHz and up, there is no cheap solution, and you need to be a lot more specific about your requirements.

author: DaJMasta
author_rank: Super Contributor
timestamp: November 27, 2019, 06:48:54 pm
content: Used Hioki LCR HiTesters will probably fit the bill, I've got a 3532-50 which goes up to 2MHz and reads out 5.5 digits. Probably usually on the higher end of your price point, but these Hioki meters can be found cheaper than Flukes or HP units and aren't full fledged impedance analyzers going for several thousand dollars.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 27, 2019, 11:40:09 pm
content: The Analog Discovery software is called "Waveforms". You can download it and test it with your computer's sound card (at lower frequencies of course), to see if you get on with it.I'm pretty impressed, personally. It really packs a lot of boat anchors into a very small space.

author: AJ3G
author_rank: Regular Contributor
timestamp: November 28, 2019, 01:18:48 am
content: First, thank you for all of your responses. I am going to attempt all of them in one post.edavid - I was not aware the AADE was not sampling L/C at 1MHz. It might be helpful to explain the application I had been using it for. I make Low Frequency 1- 30 MHz Filters. I tend to buy capacitors in large quantity’s with tolerances between 5 - 10% and sort them by the 100th of a pF per value. This allows me to get within 1% of the design value, thus allowing me to make slight tweaks to the inductor value to achieve the desired passband response. Of course, I did use the AADE to check the Inductor values too, for a sanity check.I do have a LEADER 745 LCR Bridge. I found this was acceptable for getting values for low frequency filters, but as I approach 30 MHz the AADE seemed much better, and of course, there was a difference in value between what the LEADER and the AADE measured, which I attributed to the sampling frequency.I have looked at the DER, and I have heard excellent reviews on this product. That’s worth looking into again.DajMaster - I am a big fan of Hioki Instruments. I did look at them new, but I have not seen any used. I think for sure new prices are more than I am willing to spend at this time.SilverSolder - I have briefly reviewed the page for the Analog Discovery, and will certainly take a look at it more in depth..Rich

author: DaJMasta
author_rank: Super Contributor
timestamp: November 28, 2019, 01:33:35 am
content: Quote from: AJ3G on November 28, 2019, 01:18:48 amIf you're willing to wait, I think I paid about $600 for mine, but the condition was unknown. They show up from time to time on ebay, and there are quite a few model numbers that, especially if the seller doesn't know what it is, may be a ticket to finding one affordably. Not a lot of stock available, I think, but they're the right age to be coming up used, so they do show sometimes.

author: joeqsmith
author_rank: Super Contributor
timestamp: November 28, 2019, 03:55:08 pm
content: Quote from: AJ3G on November 27, 2019, 02:48:41 pmThe NanoVNA can be used well above 100MHz and costs about $50.

author: edavid
author_rank: Super Contributor
timestamp: November 28, 2019, 04:40:53 pm
content: Quote from: AJ3G on November 28, 2019, 01:18:48 amWhat is the smallest capacitor you need to measure?The Leader LCR-745 only works at 120Hz and 1kHz, so it's not well suited to measuring small capacitors. For small NP0 capacitors, this is probably not because they actually vary in capacitance with frequency, but just because of measurement difficulties. For practical capacitors (> 1pF), a 100kHz LCR meter like the DE-5000 would be much better than the LCR-745, and should meet your needs.However, if you were happy with the results you got from the AADE meter, you don't need to spend even $100. You could just buy an "LC200A" for $30.Quote from: joeqsmith on November 28, 2019, 03:55:08 pmIt seems like a very poor choice for the OP though.

author: AJ3G
author_rank: Regular Contributor
timestamp: November 28, 2019, 06:11:08 pm
content: Hi Joe - I like the NanoVNA but not for this application. I have other needs for a VNA.edavid - The lowest I typically go is about .5pF and that is rare. For anything less than .5pF, I make “Gimmick Capacitors” and trim them until I get the desired frequency response. While the AADE did work well for me, the one complaint I did have was the test jig (homebrew). I noticed the DE 5000 has some models with much nicer jigs than I had cobbled together for my AADE.Rich

author: AJ3G
author_rank: Regular Contributor
timestamp: November 30, 2019, 12:01:15 am
content: All:I have a line on a Agilent 4284A which has some issues, but the price is very reasonable. Anyone have any experience with this LCR Meter? I have been doing some general search for accessories, and those seem very expensive. I also note boards are not abundant on the used market.It’s being offered at $500.00, but the issues are unknown.Rich

author: ocw
author_rank: Regular Contributor
timestamp: November 30, 2019, 01:05:51 am
content: While I have better ways of measuring capacitance and ESR at frequencies up to 1 GHz via vector analyzers, I decided to try and measure data at lower "high" frequencies using my Analog Devices' EVAL-AD5933EBZ evaluation board. See the attached picture of it andhttps://www.analog.com/media/en/technical-documentation/user-guides/UG-364.pdfThe AD5933 is an impedance converter which can indirectly measure capacitance via its impedance. While Analog Devices only rates the AD5933 up to 100 kHz, it mentions its use beyond that frequency. I thought that I would try it even further up to 300 kHz. After calibrating the evaluation board using 175k 0.1% resistors, I measured a 3.0 pF mica capacitor which was only rated at +/-0.5 pF. It measured the impedance at 300 kHz as being 166.3 kohms (see the attached pictures of the software displays). That translates to 3.19 pF! With the phase being shown as being 90 degrees at 300 kHz, that indirectly shows an insignificant ESR at that frequency, as expected.While not the perfect thing for the task, it was an interesting experiment. Perhaps it's time for higher frequency tests.

author: AJ3G
author_rank: Regular Contributor
timestamp: November 30, 2019, 01:42:02 am
content: Yes I would love to see a higher frequency test, but even at 300KHz that is impressive.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: November 30, 2019, 01:24:19 pm
content: I too build filters in the HF (1~30 MHz) and would love an “easy” means to measure toroidal inductors at those frequencies. I have an LC200A meter (500 KHz) that clearly isn’t up to the job, but does work fine to measure capacitors reasonably well (or at least it matches the printed values of 1% ones).I’ve tried using both an MFJ and a Rigexpert antenna analyser to measure components at their intended working frequencies, but found the results unreliable. The most accurate “cheap” method to measure inductors has been to use a grid dip oscillator and check the resonance of a parallel tuned circuit using a known value capacitor. It’s long winded, but works.

author: AJ3G
author_rank: Regular Contributor
timestamp: November 30, 2019, 02:10:56 pm
content: I too have a grid dipper, and I also can determine L by measuring frequency response in SITU. This of course, takes considerable time. The AADE was good for measuring Ceramic NP0/C0G capacitors. Unfortunately, its becoming increasingly difficult to find leaded (non SMD) parts rated at >1KV. I typically use Ceramite, and capacitors I obtain from a Vendor in China who sells capacitors that are rated for 5 - 10KV of the right temperature coefficient.Ceramite is going to discontinue the line I have been using, so I have decided to change all the capacitors over to SMD. This will require the implementation of a PCB, but I am ok with this. I am now faced with measuring thousands of little SMD components, and thought it’s high time to set up something which would allow faster and more reliable measurements of these components.My AADE performed well measuring inductance. I use Micrometal cores, and for standard inductors, if your count is correct, you are pretty much guaranteed to be within the tolerance of the core. When I am forced to use Trifilar, Quintifilar, etc windings then I do like to perform a sanity check, because its easy to lose count.Rich

author: edavid
author_rank: Super Contributor
timestamp: November 30, 2019, 02:28:29 pm
content: Quote from: AJ3G on November 30, 2019, 02:10:56 pmHave you considered LCR tweezers (aka smart tweezers)?

author: AJ3G
author_rank: Regular Contributor
timestamp: November 30, 2019, 02:45:43 pm
content: edavid:I had not thought of tweezers. This might be worth a look. Many years ago I had a set of ExTech LCR tweezers. I think Mouser had a sale on them when they were new, and I gave them a try. Those were terrible in my opinion, but maybe these have improved with time.Rich

author: ocw
author_rank: Regular Contributor
timestamp: November 30, 2019, 04:32:12 pm
content: My AD5933EBZ evaluation board measured my 3.0 pF (+/-0.5 pF) capacitor fairly accurately up to 500 kHz. It measured 93800 ohms impedance there which translates to 3.39 pF (see the attachment). I used 100k 0.05% resistors for calibration.As you go higher in frequency, it becomes more important that the impedance being measured is close to the calibration resistance. If not, the capacitor being tested might incorrectly look more like an inductor with increasing impedance at higher frequencies. The measurement frequency sweep makes that easy to see. With care even higher frequencies are possible, though not very convenient for practical use.

author: Meltdown2011
author_rank: Newbie
timestamp: November 30, 2019, 08:23:06 pm
content: Hello AJ3G4284A is old but good LCR meter. But don't buy cheap unknown condition 4284A. Its service period had expired. Keysight provides only limited support and repair cost is usually very high even if it is repairable. I suspect that original owner discarded it because it can't be repaired.

author: bson
author_rank: Unknown
timestamp: November 30, 2019, 09:06:10 pm
content: Quote from: ocw on November 30, 2019, 01:05:51 amThat's very cool. What if you accurately measure the reference resistor at 300kHz first?

author: ocw
author_rank: Regular Contributor
timestamp: November 30, 2019, 09:31:05 pm
content: QuoteThe reference resistor is seen by the AD5933EBZ as "perfect," what the unknown as compared against. So, no matter how good the reference resistor actually is it will be measured as what you have entered its resistance (or impedance) as. That is why I used a 0.05% accuracy resistor there. The evaluation board can then accurately measure the impedance (which should be almost the same as it reactance) of a capacitor. It could also measure the actual impedance of a wirewound 10% resistor at a chosen frequency/frequency range.The board was not made to be a precise test instrument, although it does a pretty good job of doing that within its range and limitations. It was meant to demonstrate the AD5933's capabilities and let you expand on the evaluation circuit.

author: AJ3G
author_rank: Regular Contributor
timestamp: December 01, 2019, 09:11:00 pm
content: Quote from: Meltdown2011 on November 30, 2019, 08:23:06 pmYes, it looks like a nice instrument. You are right. When I went over to look at it, the poor thing looks as though it was recovered from the bottom of the ocean. There was rust/corrosion inside and outside. I am all for the challenge of a repair, but I told the seller he would have to pay me just to take the poor thing away.Oh well, its fun to look at the stuff, nonetheless!Rich