Hi all!
I was trying to measure some of these thin film inductors (
http://data.leocom.kr/datasheets/316338_360095.pdf) with my DER DE-5000.
I wasn't looking for an accurate measuring, but the results don't make any sense. And I know, 100 KHz is not the best (or most appropriate) frequency, to measure these types of inductors. But please, let me continue.
Later I started to thought than maybe have to do with their DC resistance, so I did a little test:
I measured ~ 1cm wire in series with 1 ohm resistor. And I get a reading of ~ 0.15uH (Ls) with 1 OHM (ESR), instead of ~ 10nH (Ls) and 1 OHM (ESR). However if I measure only the wire (without resistor), the DE-5000 show ~ 13nH.
So, what is happening here? What is wrong?
I repeated the test several times, calibration included of course, even I try with short cables for the DUT (see the attached picture at the end). But always I got the same result.
The exact values were:
- Wire: 1.3cm (long), 0.3mm (thick) ie. arround 11.5nH. ->
http://chemandy.com/calculators/round-wire-inductance-calculator.htm- Resistor (thin film): 1 ohm 1% 805 case.
And the final question is:
Do you get similar results with your IET DE-5000, DE-6000 or DER DE-5000?
Several weeks ago (February 3, 2016), I sent an email to the DE-5000 manufacturer, to let him know about this. And guess what, no reply yet, and I'm afraid than ever.
If I'm not wrong the accuracy on the DE-5000 is expressed as an % of rdg. plus x digit, right?
So for a reading of 0.100uH @ 100KHz we have an uncertainty of +-0.0075uH (2.5% +5)
Or IET/DER is expressing the error in another way?
Edited to change the subject title.