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East Tester ET3502 LCR-Bridge

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egonotto:

--- Quote from: mawyatt on August 12, 2024, 10:23:39 pm ---Got a Wurth RF 0603 Chip 10nH Inductor & Pulse Electronics with Standard SMD fixture and measured with IM3536 at 300KHz and 100KHz. Readings are in nH (Vdut mv/ Idut ma).

DUT Device                        100KHz                      300KHz                        1MHz

Wurth 10nH                     11.86 (20.04/102.2)     11.83 (22.95/101.7)      11.79 (41.35/98.22) 
Pulse Electronics 10nH      10.34 (28.05/101.2)     10.38                           10.37

With TH2830   

Wurth                              11.878 (5.22/33.16)
Pulse                               10.574 (7.97/33.07)

.....                               

--- End quote ---

Hello,

I have calculated the impedance. I must have made a mistake somewhere, because it doesn't add up.

Best regards
egonotto

mawyatt:

--- Quote from: Martin72 on August 12, 2024, 09:17:10 pm ---....
From an HF point of view, this fixation is simply garbage.
And not only this fixation, others too.
They are all not "HF-tight" ....


--- End quote ---

Since these fixtures are somewhat direct clones of the Tonghui TH26008A which is rated to 120MHz and states, "Applicable to: SMD devices, high frequency small capacitors and small inductances." are you implying that their TH26008A is garbage??

https://www.tonghui.com.cn/en/product_144.html

BTW what is "HF-tight"?

Honestly think Tonghui knows what they are doing and we've certainly got excellent results after modifying the clones but only to 8MHz tho :-+

Not too impressed (exposed blades in handle) with the Tonghui Kelvin Clips tho, but haven't seen any others that appear better.

Hope you get over your cold soon!!

Best

mawyatt:

--- Quote from: egonotto on August 12, 2024, 10:54:27 pm ---
--- Quote from: mawyatt on August 12, 2024, 10:23:39 pm ---Got a Wurth RF 0603 Chip 10nH Inductor & Pulse Electronics with Standard SMD fixture and measured with IM3536 at 300KHz and 100KHz. Readings are in nH (Vdut mv/ Idut ma).

DUT Device                        100KHz                      300KHz                        1MHz

Wurth 10nH                     11.86 (20.04/102.2)     11.83 (22.95/101.7)      11.79 (41.35/98.22) 
Pulse Electronics 10nH      10.34 (28.05/101.2)     10.38                           10.37

With TH2830   

Wurth                              11.878 (5.22/33.16)
Pulse                               10.574 (7.97/33.07)

.....                               

--- End quote ---

Hello,

I have calculated the impedance. I must have made a mistake somewhere, because it doesn't add up.

Best regards
egonotto

--- End quote ---

You didn't make a mistake, we did and in hind sight we shouldn't have posted the Voltage and Current values :o

The impedance calculated from these values must include the LCR Open and Short Calibration coefficients to be correct for the DUT, these coefficients are not directly available.

We should have realized this before posted about Martin's readings  :-[

Thanks for pointing this out, we'll remove those for clarity!!

Best,

egonotto:
Hello,

thank you for your answer.

The voltage at the DUT should be easy to measure using the 4-wire method. The current is distorted by the shunt.

You should be able to estimate the impedance of the shunt from the values given. The phase shift must be taken into account.

I still have to think about whether it is possible to calculate the shunt from the given values, i.e. measured inductance, frequency, measured voltage and measured current. The ohmic resistance of the coil should be negligible in this case.

Best regards
egonotto
PS: I don't think that's possible. If you look at the series connection of shunt and DUT, you have two unknowns, the shunt and the voltage that is applied to the series connection.

mawyatt:
The problem with these type SMD fixtures (why we developed the Split-Kelvin type) is the 4 wire Kelvin connection is made at the entry to the plunger bottom, not at the Plunger tip which makes contact with the SMD DUT.

If you look at Martin images you can see where the Force and Sense (Hcur-Hpot and Lpot-Lcur) wire pairs enter the case top cover to the plunger, this is where contact is made, not at the DUT. The LCR meter will "attempt" to remove this unmeasured connection from the Force Sense connection to the DUT by means of the Open and Short Calibration, however this is far from ideal.

The method we developed attempts to remove this uncertainty by keeping the Force and Sense wire separate until they are connected by the SMD DUT end terminals, thus removing most of the uncertainly in measurement. This is a little tricky to get all 4 connections to the SMD DUT, and why we created the rough contact surface texture, but with a little patience results are quite repeatable down to milliohm Z levels!! Of course this assumes that you are using an LCR meter capable of resolving this low a level!!

Anyway, thanks again for pointing out our improper numeric posting :-[

Best,

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