Compatibility of different LCR test fixtures - Page 1
Forum section: electronics / testgear

author: salomonander
author_rank: Regular Contributor
timestamp: October 13, 2025, 08:58:27 pm
content: Hey there,I scored an R&S LCX100 for an amazing price. It comes with no fixtures though. Buying new R&S ones would kind of kill the bargain charactercan i use fixtures from other manufacturers without compromising anything? Say GW Instek, older Hameg or Tonghui… is there anything inside these boxes besides the connectors?Some manufacturers offer the locking levers only on the two outer bnc connectors. Does this matter in any way?Thanks!

author: MathWizard
author_rank: Super Contributor
timestamp: October 13, 2025, 09:02:06 pm
content: Your pictures just disappeared for me, those BNC locking levers look cool, I wish I had some for my AWG cables.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 13, 2025, 09:03:57 pm
content: TongHui's fixtures are very good, and many other companies rebrand them. Hioki also makes great fixtures, but they're more expensive.If you get tired of the LCX100, let me know.

author: salomonander
author_rank: Regular Contributor
timestamp: October 13, 2025, 09:59:58 pm
content: Great, the tonghui is a fraction of the priceHere are the pictures again. i wouldnt be suprised if they make the r&s fixture as well. They look very similar. The lcx has not even arrived yet. Im just about to make the payment. I was chasing the older hm8118 for over a year and missed two great deals. But this new lcx is actually the same price as the used hm8118 were. So i got really lucky. I assume there is no additional circuit in the dedicated transformer fixture either?

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 13, 2025, 10:13:50 pm
content: Those probably are made by TongHui. I dunno any more details on that fixture though.

author: salomonander
author_rank: Regular Contributor
timestamp: October 13, 2025, 10:25:02 pm
content: Indeed looks the same. The tonghui is 70$ on amazonthe r&s is at least one zero more. Thats crazy!

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 13, 2025, 10:33:37 pm
content: Careful ordering them online, including Amazon. There are lots of fakes. For $70,probablya fake. Might still be good though, just not as good.

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 13, 2025, 11:13:06 pm
content: There's no difference between the 4 locking levers and 2 locking levers besides ease of use (2 levers are easier to use).I have previously removed the two center BNC's on a test fixture with 4 locking levers and replaced them with standard BNC's with the outer collar cut off to convert them to 2 lever and it all works fine.I then used the spare locking lever BNC's on my own custom test fixture.As for the quality, the Tonghui fixtures are fine. I tend to open them up and give them a tweak (i.e. remove paint overspray inside for better contact for grounds and shields etc), the usual thing for a cheaper bit of equipment.There are a few threads around on playing with these cheap test fixtures with more detailed info.I buy from Aliexpress and usually buy the cheapest option, haven't had a problem yet.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 13, 2025, 11:26:54 pm
content: That's all good advice except for one thing: If a text fixture issupposedto come with four levers, but only comes with two, it's 99% of the time a fake. The amount of levers don't really matter otherwise. My more expensive Hioki L2000 comes with only 2.

author: mkissin
author_rank: Regular Contributor
timestamp: October 14, 2025, 01:17:37 am
content: I have an LCX200 with the Z2 fixture (Kelvin clips). It has the 4 locking levers and they're actually a problem.Each lever interferes very slightly with the one to the left of it, meaning you can't rotate it quite as far as it needs to go. By the time you get to the final level, it can't rotate enough to actually fully engage the BNC lock.Doesn't affect performance, but it bothers me they the overlooked this when it was so bananas expensive.Maybe I can force them over a little so they rotate properly? But again, it was so expensive I don't want to risk damaging them.For future fixtures, I'm just going to get the Tonghui ones.

author: mawyatt
author_rank: Super Contributor
timestamp: October 14, 2025, 01:47:48 am
content: Quote from: salomonander on October 13, 2025, 09:59:58 pmFor sure the images 3841 and 3843 are Tonghui rebrands as we pointed out a few years ago. Save some $ and get the equivalent performance with the true OEM Tonghui which we have, just don't expect much support from Tonghui, they are skimpy here.Best

author: mawyatt
author_rank: Super Contributor
timestamp: October 14, 2025, 01:59:16 am
content: Quote from: MathWizard on October 13, 2025, 09:02:06 pmYou can 3D print them like we did here. Found the files somewhere but can't remember, just do a search.https://www.eevblog.com/forum/metrology/lcr-meter-tests/msg5985403/#msg5985403Note you may need to "adjust" the BNC opening for a snug fit. The BNCs we used were just standard BNCs for a panel mount from Amazon.Best

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 14, 2025, 04:22:51 am
content: Quote from: KungFuJosh on October 13, 2025, 11:26:54 pmWhen it comes to stuff sourced from China on Aliexpress, most of it is a copy of a copy anyway...

author: RolandK
author_rank: Regular Contributor
timestamp: October 14, 2025, 05:01:25 am
content: All the R&S fixtures are from tonghui. I have rs hameg hz188 and identical tonghui.Beware of the fake ones (missing tonghui in description and slightly different picture) they omit the shield inside between H and L.In the transformer testfixture LPot and LCurr are bridged. I added a switch like in the hp one to exchange HPot and HCurr. A Knitter switch just fitted between the BNCs.Yes B&K Precision is brand labeling them, too.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 14, 2025, 05:02:25 am
content: Quote from: TERRA Operative on October 14, 2025, 04:22:51 amThat's true. But if you know what to look for, your odds of getting something genuine are improved.

author: gamalot
author_rank: Super Contributor
timestamp: October 14, 2025, 06:46:01 am
content: I‘ve got a cheap 2nd hand LCR meter and test fixtures and accessories from different brands. honestly I don't think that's a problem at all. Your LCR has way better specs, but as long as you keep an eye on the frequency characteristics when picking 3rd party fixtures, you should be totally fine.

author: gamalot
author_rank: Super Contributor
timestamp: October 14, 2025, 06:57:19 am
content: Quote from: salomonander on October 13, 2025, 10:25:02 pmSeventy bucks is insane, this thing only goes for 300 RMB in China!

author: salomonander
author_rank: Regular Contributor
timestamp: October 14, 2025, 10:29:43 am
content: Thanks guys, you saved me a fortuneNow im wondering if i could open up one of these tonghuis and add mawyatts circuit in order to safely apply external bias voltage. Would that work? It would save me another fortune

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 14, 2025, 02:25:52 pm
content: Quote from: salomonander on October 14, 2025, 10:29:43 amYou want to leave the thing tightly sealed...at least until the calibration expires. Besides that, there's no reason to add it internally and risk other problems. Just get a DC bias fixture.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 14, 2025, 02:26:26 pm
content: Quote from: gamalot on October 14, 2025, 06:46:01 amYou may have got a good deal on those fixtures, but some of them are not even close to cheap. I'll take that L2001 if you're bored with it.

author: salomonander
author_rank: Regular Contributor
timestamp: October 14, 2025, 02:31:46 pm
content: Thanks,thats what i ment. I will not remove the seal on the lcx. Im thinking about modding one of these tonghui test fixtures.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 14, 2025, 02:44:00 pm
content: Quote from: salomonander on October 14, 2025, 02:31:46 pmOh, then yeah, go to town.Mike's got some great mods/creations for the fixtures. I have a couple versions I made of his SMD fixture that work great.If you're going to mod it, then the cheap knockoffs of the TongHui fixtures can be a good place to start. Or the even cheaper completely generic fixtures if you're going to gut it anyway.

author: mawyatt
author_rank: Super Contributor
timestamp: October 14, 2025, 02:51:36 pm
content: Quote from: salomonander on October 14, 2025, 10:29:43 amWhat fixture are you considering?We did such with a cheap AliX SMD fixture (no PCB involved), not a Tonghui, and the results were good.Best

author: gamalot
author_rank: Super Contributor
timestamp: October 14, 2025, 03:13:22 pm
content: Just a heads up, fake Tonghui is pretty common on sites like AliExpress, Taobao, and others. As a Chinese I find that really disappointing.Since Tonghui's official website is hard to access (at least from Australia in my experience), I usually check their Tmall store for genuine product photos to avoid getting scammed.https://tonghui.tmall.com/category-863990916.htm

author: mawyatt
author_rank: Super Contributor
timestamp: October 14, 2025, 03:26:06 pm
content: As far as we know Tonghui doesn't authorize any resellers on AliX, so caution is advised when acquiring Tonghui products from AliX.Best

author: salomonander
author_rank: Regular Contributor
timestamp: October 14, 2025, 03:46:21 pm
content: Thanks, i will buy from the official distributer in my country. I already received the contact from tonghui. And im not shure wich fixture it will be yet. Not the cheapest model, as they have limited bandwidth and i want to go up to 200khz. So one of the th26005 variants i guess. I will have to do some more research.

author: mawyatt
author_rank: Super Contributor
timestamp: October 14, 2025, 04:14:13 pm
content: If you plan on leaded components look at the TH26048A, this is a nice fixture and the blades that engage with the DUT leads are quite good and have good pressure, just make sure you clean your DUT leads with IPA for better contact for low Z measurements.For Kelvin Clips the TH26011CS are good, altho the Hioki are probably better (don't have the Hioki so can't compare). The TH26005B Tweezers are OK, altho we seldom use them.Best

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 14, 2025, 05:14:52 pm
content: Quote from: mawyatt on October 14, 2025, 04:14:13 pmI have both, and the Hioki are better (better shielding etc). They also cost $1000 more, and I don't think they're $1000 better.

author: salomonander
author_rank: Regular Contributor
timestamp: October 14, 2025, 06:39:43 pm
content: Thanks, ill getbthe fixtures you suggested. Do you maybe know what the difference is between the TH26038 and the th26038a? I whish there was a proper datasheet with all the suffixes explainwd. Or is there such a thing?

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 14, 2025, 08:11:15 pm
content: The only difference I've seen is that the A version is supposedly the upgraded version. I haven't seen reliable specs one way or the other.