LCR meter questions and maybe recommendation.

[rwgast_lowlevellogicdesin]

Ive stepped away from hobby electronics for a while just busy work(electrician) and being a single parent, but have found myself wanting to get back in to some projects lately. I have most test equipment I need, the only thing I am missing besides a decent spectrum analyzer is an LCR meter. I was harvesting some parts the other day and realized I had no way to easily measure the IF cans I pulled. In the past when measuring inductance I have relied on one of three techniques.

#1 A common ebay TC-1 transistor/component tester
#2 Siglent SDS1104x scope controlling Siglent SDG1032x AWG@(hacked to 60mhz), that can plot I/V/phase etc etc
#3 A nanoVNA2

The TC-1 is great for a quick ballpark number as long as the tester recognizes it as an inductor and not a wire wound resistor, which is a huge problem with most inductors for RF filtering and even switching power supply design, because there inductance is to small for the TC-1 to measure. Using the scope/awg gives pretty decent results up to 60mhz but is kind of a PITA to set up. NanoVNA is also a  PITA to use to measure components because everything is has to be 50ohm and you have to build some kind of a test fixture.

After watching some reviews of handheld LCR meters I'm left with a few questions. First of all do they commonly give you the Z value at the meters selected frequency. I see that they mostly give you Q,D and X but the only one I have seen giving Z is the Peak Atlas LCR45.

Also im having a hard time understanding how useful an LCR meter is for measuring inductors you plan to use outside the frequency range outside the meter. For example if I use a calculator to wind an air core coil for a VHF filter or something can I use the LCR meter to verify the value of the coil? What about coils using iron or ferrite cores? Does the frequency a coil is driven at effect the inductance of the coil? If so that would make the meter useless for any coil being used at a frequency higher than 100khz or whatever the LCR meters top frequency is? Even a switching power supply runs at higher a frequency than the pretty standard 100khz of these meters.

[tautech]

2 decades ago I was also looking at LCR meters and also getting into SMD.
I selected smart tweezers as a universal solution for both which quickly became an indispensable tool.

Much has changed and now many bench LCR devices exist yet SMD tweezers remain my tool of choice.
I highly recommend you look hard at ST42 and its record of development here:
https://www.eevblog.com/forum/testgear/design-a-new-precision-lcr-tweezers/

For more detailed info, Shannon's website might be useful also:
https://shannontweezers.github.io/docs/introduction/

[shabaz]

From what you mention, probably a VNA is way more useful. Agree it's not as convenient as a couple of of alligator clips to perform a measurement, but you'll get way more satisfactory results since you're measuring at the frequency you'll actually be using it.

I have a couple of LCR meters, plus other tools that perform similar-ish operations, but I probably use the VNA more often, especially if as you say, the frequency of operation is going to be much higher.

For toroid and air core, calculations can be fairly accurate, so unless even more accuracy is needed, I might not measure and just tune in the circuit.

Sometimes I might use ready-made inductors, e.g. CoilCraft kits can be handy, they come in tolerances like 2.5%. I have no issue constructing DIY inductors, and keep various ferrites and iron cores handy. For typical HF/VHF work, software like Coil64 is as accurate as is practically possible without electromagnetic simulation tools I think - I've had a good experience with that software.

[Martin72]

2 decades ago I was also looking at LCR meters and also getting into SMD.
I selected smart tweezers as a universal solution for both which quickly became an indispensable tool.

Much has changed and now many bench LCR devices exist yet SMD tweezers remain my tool of choice.
I highly recommend you look hard at ST42 and its record of development here:
https://www.eevblog.com/forum/testgear/design-a-new-precision-lcr-tweezers/

For more detailed info, Shannon's website might be useful also:
https://shannontweezers.github.io/docs/introduction/

For the applications he has outlined, the tweezers can only be considered as a supplement.
Or I would only get them as a supplement, not for everything, the maximum frequency alone is too low for that.

[nctnico]

You need multiple instruments. An LCR meter is OK for determining inductance. For an inductor with a core, it is nice to be able to have current flowing through it so you can measure the saturation point. A VNA is a good instrument to measure the self resonance frequency of an inductor.

[Martin72]

For an inductor with a core, it is nice to be able to have current flowing through it so you can measure the saturation point.

Yes, we have built a testing device for this, which is not available on the market in this form.
Or only one and it has to be connected to a PC, ours works independently with the option of connecting a scope, precisely because of the saturation sighting.
The principle behind it is known and exists in construction proposals on the net, but ours can generate currents of up to 200A, so you can stress coils a bit.
A normal LCR cannot keep up with this, and depending on the core material, completely incorrect values are even displayed.

[tautech]

2 decades ago I was also looking at LCR meters and also getting into SMD.
I selected smart tweezers as a universal solution for both which quickly became an indispensable tool.

Much has changed and now many bench LCR devices exist yet SMD tweezers remain my tool of choice.
I highly recommend you look hard at ST42 and its record of development here:
https://www.eevblog.com/forum/testgear/design-a-new-precision-lcr-tweezers/

For more detailed info, Shannon's website might be useful also:
https://shannontweezers.github.io/docs/introduction/

For the applications he has outlined, the tweezers can only be considered as a supplement.
Or I would only get them as a supplement, not for everything, the maximum frequency alone is too low for that.

Shall we just see your impression of ST42 when you have more experience with them after they arrive.
You did weaken to ordering a pair didn't you ? 

[Martin72]

My dear Rob,
I have no doubt that the ST42 will be a good device within its capabilities.
But it can't perform miracles and make other topologies superfluous, with all due respect.
Measuring and calibrating coils and transformers is an almost daily task for us.
We use different measuring methods and different devices for this because no device can do everything.
So I have some experience with this, so I can already say that it won't be any different with an ST42.
It is limited in its measuring voltage, it is even more limited in its measuring current and finally in its measuring frequency.
In addition, the mechanical design alone means that it can only measure SMD components.
You can buy the ST42 in addition, as a stand-alone measuring device it is too limited in principle.
Believe me.
(That doesn't change the fact that it's already on my list)

[tautech]

Yes of course Martin but your measurements needs do not equate to what other might require.

What is good enough is very different for us all. 

[rwgast_lowlevellogicdesin]

Thanks for the info, ill probably just pick up an LCR meter to use in conjunction with my other devices. Probably the east tech desk meter or a peak lcr meter. I dont have much of a need for tweezers, if im using smd i trust the package.. this is more for verifying home made coils.

[tautech]

Thanks for the info, ill probably just pick up an LCR meter to use in conjunction with my other devices. Probably the east tech desk meter or a peak lcr meter. I dont have much of a need for tweezers, if im using smd i trust the package.. this is more for verifying home made coils.

Which was my initial need too.

Just because they are SMD tweezers don't by any means think that's all they can do.

[shabaz]

I don't know if the online specs for the ST42 are correct or not, but it's a bit concerning. The minimum inductance is 0.5uH, which is going to be troublesome if checking typical coils for (say) VHF purposes. I often use far smaller inductances, hand-wound.

Appreciate not everyone will need small inductances, but OP has a callsign in their signature, so there's a chance small inductances might be needed for commonly-used bands, so worth raising as a thing to check, before ruling any LCR meter in or out.

[KungFuJosh]

I don't know if the online specs for the ST42 are correct or not, but it's a bit concerning. The minimum inductance is 0.5uH, which is going to be troublesome if checking typical coils for (say) VHF purposes. I often use far smaller inductances, hand-wound.

Measuring in the nH range is more difficult, and even more expensive LCR meters have trouble doing so. I think 500nH is fairly impressive for such an inexpensive tweezers.

The attached chart is for a high quality bench LCR series that costs between 10 to 20 times more than the ST42, and the 100nH to 10nH ranges are clearly not ideal, even at that price range.

[shabaz]

Agree, it seems a useful tool in any case. I just meant to highlight it in case the OP intends to measure smaller inductances.

[Martin72]

Yes of course Martin but your measurements needs do not equate to what other might require.

What is good enough is very different for us all. 

It has little to do with it, I just wanted to point out that you can't cover everything with one device and if the OP only has standard tasks (he doesn't), then he can use almost any meter.

[HalFoster]

For all around usefulness and accuracy at a affordable price the best option, IMO, is a DE-5000 with added (easily DIY) kelvin clips.  I have three different lab grade .05% accurate LCR meters, both testing up to 1MHz with programmable offsets, but the one that gets used constantly is my DE-5000 - it's easy to use and "just works."  As with much test gear the cost goes up pretty much exponentially when you start requiring higher end functionality - in ESR meters that pretty much equates to maximum test frequency.  Personally if I was needing to characterize inductors at higher frequencies I would get a DE-5000 and spend the money saved on a good VNA - it would do the job and add a tremendous amount of additional options to your bench.  If you haven't, check out what the little Nano VNA is capable of - pretty amazing, IMO.

Hal

[beatman]

I use the extech lcr200 and keysight u1732c .Extech is more speedy than keysight.Accuracy between units variance from 0.5 to 2 % depence what i measure.Keysight have big hidden menu to change parameters and preferences. I like booth units.

[mawyatt]

To use an LCR meter over a broad range of components and values requires some understanding of the measurement principles if one expects reasonable accuracy.

The low cost all-in-one component devices utilize a pulse technique whereas the more expensive lab type bench LCR meters utilize sine-wave measurement techniques (can explain if interested), the later usually better for accurate measurements, altho the all-in-one do a respectable job with most components.

Small inductors represent a low impedance at lower frequencies which limits the measurement capabilities, the LCR meters allow the frequency to be set and generally the higher the better for small inductors as the impedance is directly proportional to frequency (well below the self resonate frequency). Since these meters actually measure DUT voltage and current, a small inductor (low impedance) produces a low voltage and high current, thus difficult to measure accurately. The reverse is true for small capacitors (high impedance), low DUT current and high DUT voltage.

Many of the quality LCR meters have a table/graph which shows the component ranges, frequency and the accuracy "Sweet Spot" which should be consulted if one desires the most accurate results.

The mentioned DE-5000 handheld LCR meter is based upon a specialized chip-set which performs almost all the functions and measurements, keeping the cost reasonable. We have one and it has demonstrated good performance against our Lab Grade Tonghui TH2830 and Hioki IM3536 LCR meters.

We have and utilize all 3 meters, the IM3536 goes to 8MHz and why we have this, however it's expensive (~$4600), the TH2830 is 100KHz (~$1000) and high quality good value Lab Bench LCR meter, and the DE-5000 (~$200) for the general measurements.

Another thing one might consider is having a set of stable "Reference Components" to check. We have various resistors and capacitors, altho no inductors, we can compare. Precision stable resistors are abundant, however capacitors are more difficult to find. C0G/NP0 ceramic capacitors are good for low values, Mica & Polystyrene good more mid values, and Polypropylene for higher values.

Best, 

[KungFuJosh]

While the Tonghui LCR is awesome, their support sucks. Better to get the rebranded SourceTronic version if you can. 😉

[rwgast_lowlevellogicdesin]

One question no one answered was is it common for these meters to give a Z reading on the component at the meters selected frequency. The peak lcr meter does do this, i watched kerry wongs review of a couple lcr meters and the all seemed to give values for D,X,Q and ESR but he never showed Z so im not sure if any meter besides peak does this.

At higher frequency i usually work at 200mhz and under and L band(~1-2ghz). I do use a nanoVNA2 for that stuff. Ive been looking in to buying a siglent spectrum analyzer with VNA option, although im not sure how much better that would be for VNA use.

[KungFuJosh]

One question no one answered was is it common for these meters to give a Z reading on the component at the meters selected frequency. The peak lcr meter does do this, i watched kerry wongs review of a couple lcr meters and the all seemed to give values for D,X,Q and ESR but he never showed Z so im not sure if any meter besides peak does this.

Plenty of LCR meters do include Z. The Shannon ST42 tweezers do. The TongHui/SourceTronic 283X series do. At least some of the Instek LCRs do too. You can search for LCRZ meters or Impedance Meters too.

[mawyatt]

@OP

The LCR meters don't measure L, C nor R directly, they measure the complex voltage across DUT and complex current thru DUT, then compute the desired display parameter from such.

Almost all Bench LCRs meters show Z, some handhelds don't (like the DE-5000).

Best,

[indman]

Almost all Bench LCRs meters show Z, some handhelds don't (like the DE-5000).

You are wrong, the DE-5000 can show Z, otherwise there would be no point in this chipset.
The DE-5000 displays much more information when connected via USB to a computer.
Here is an example of such measurements

[mawyatt]

Almost all Bench LCRs meters show Z, some handhelds don't (like the DE-5000).

You are wrong, the DE-5000 can show Z, otherwise there would be no point in this chipset.
The DE-5000 displays much more information when connected via USB to a computer.
Here is an example of such measurements

This isn't about having a computer to read the LCR meter and computer then display results on something else, what's the point of a handheld with a computer dangling on a USB cable to read/compute/display the results!!

The DE-5000 we have can NOT DISPLAY Z , at least the DE-5000 we have.

Can anyone post an image of a DE-5000 that shows Z on it's display??

Best,
 

[indman]

The DE-5000 can display Z as well as other important circuit parameters at a resolution not available on the built-in display when connected to a computer!!! The fact that it does not show this data on the display does not diminish its value as a full-fledged LCR meter. Whether you take advantage of these opportunities or not is up to you. I, for example, use it and I don't suffer from it at all.