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East Tester ET3502 LCR-Bridge

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Martin72:
Hi Mike,

This is not a problem, the output resistance can be selected for the ET35 (as well as for the small ET44/45).


--- Quote ---This is why the TH2830 has a 33X lower 3 ohm range
--- End quote ---

As with the ET35, you can choose between 30 and 100 ohms for the TH2830/ST2830.

mawyatt:
The TH2830 has a lower 3 ohm range with 30 Ohm source impedance (IM3536 is 0.1 ohm range with 10 ohm source impedance), what is the ET35 lower range?

Always use the lower range and source impedance except for higher Z components. The DUT current is mostly dictated by the source impedance for low Z DUT, so 30 ohms would give you ~3.3X the DUT current and thus ~3.3X the DUT voltage over the 100 ohm source, which makes things a little easier to resolve.

Of course this assumes the ET35 can deliver this level of current stability and accurately at frequency.

Best,

mawyatt:

--- Quote from: Martin72 on August 13, 2024, 02:12:09 pm ---
--- Quote from: egonotto on August 12, 2024, 05:33:09 pm ---Shouldn't VAC be around 0.2 mV or IAC around 100 mA?

--- End quote ---

Thanks again for this post. :-+
I simply asked ET how the VAC/IAC values come about and as always they responded promptly (which is really great).
They sent me a picture of a handwritten sketch, really cute. :D
But then you can also understand it, because in my calculations I neglected the output resistance (100 ohms).
So far so good, so understandable - but.... ;)
The engineer who drew this has made a small calculation error.
The nano value is one decimal place too low.
This has hardly any effect on the current display, but the voltage is displayed too high by a factor of 10.
So if this is the same engineer who is responsible for the software, then the same error will be found in the program.
I have therefore sent ET a picture with notes on the slip of paper.
Let's see what comes back.
Martin

--- End quote ---

Also ask, why would the ET engineer even suggest a 100 ohm source for the low Z 10nH inductor, when apparently 30 ohms is available ???

Best,

Martin72:
He did not suggest anything.
He only calculated what I had asked.

Martin72:
Hi,

Today I took the fixture and the choke/capacitor to work.
Afterwards I also retested at home with 100khz on the ET35.
I don't think you should pay too much attention to this Im/Vm thing.
While the values for the ST2830 are still correct for the choke in terms of voltage/current, they are higher for the ET35 and both are wrong for the capacitor.
I found an explanation in the ST2830 manual.
There it is expressly stated that these Im/Vm values are for information only, i.e. no accuracy is given, and they can deviate anyway if corrections (open/short/load) are used.
Presumably this is why they can also be switched off on the ST2830, so that no confusion arises. ;)
For me this is the end of the matter, it would have been nice to find such an explanation in the ET35 manual too.
But now I know, and now I'm almost sorry that I was bitching at the guys from ET before I read it in the ST2830 manual. :-X ;)



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