Products > Test Equipment
TH2830 vs TH2832
<< < (34/74) > >>
luudee:

--- Quote from: nctnico on July 09, 2023, 09:08:25 am ---Did you do a open/short calibration? What are the accuracy specs for that resistance value at those test frequencies?

--- End quote ---

Hi Nico !

Indeed, I haven't calibrated it since I took it apart, thank you for keeping me honest!  ;-)

So, after calibration, things look much better (same resistor):

200 KHz: 100.35 KOhm
100 KHz: 100.33 KOhm
 10 KHz: 100.36 KOhm

Please see my previous post for accuracy specs in the Calibration certificate.

Cheers,
luudee
nctnico:
 :-+

One thing to keep in mind when using an LCR meter is that the reading depends on measuring amplitude and phase. At some point these measurements can no longer be made with a reasonable accuracy. Most LCR meters have a graph or formula in the manual that tells you what kind of accuracy to expect for a given component value. Looking at the calibration results, you can see they don't bother measuring 100k Ohm at 100kHz and the 30k Ohm allows for a larger error margin compared to the measurement at 10kHz.
2N3055:

--- Quote from: nctnico on July 09, 2023, 11:40:11 am --- :-+

One thing to keep in mind when using an LCR meter is that the reading depends on measuring amplitude and phase. At some point these measurements can no longer be made with a reasonable accuracy. Most LCR meters have a graph or formula in the manual that tells you what kind of accuracy to expect for a given component value. Looking at the calibration results, you can see they don't bother measuring 100k Ohm at 100kHz and the 30k Ohm allows for a larger error margin compared to the measurement at 10kHz.

--- End quote ---

This.

For instance, capacity of electrolytic capacitors is routinely measured at 100/120 Hz. You NEED to measure them at that frequency to compare capacity to nominal.. At 100kHz 1000uF represent miliohms and is hard to measure.

Example diagram from old Digibridge:
mawyatt:
Another thing to keep in mind here regarding 100KHz measurement of a 100K Resistor, is at +-0.1% that's the equivalent of ~+-0.016pF (16fF) capacitance change.

Remember this is in the entire setup including instrument, DUT, any cables, fixtures and whatnot, and quality OEM Kelvin cables help but don't eliminate this potential error source. Cable bending, placement and the position of the clip tips have effects, also Kelvin techniques do not circumvent DUT shunt effects such as distributed capacitance between Kelvin clip tips which are not shielded wrt a ground shield. This is why we prefer for LCR measurements, especially high impedance and upper frequency ranges, using a test fixture specific for the type DUT, rather than Kelvin leads, even the fixture for leaded DUT like the TH26048A has proven more reliable (repeatable) than Kelvin leads in our experience.

So extreme care is necessary for precision repeatable measurements of high impedance devices at 100KHz and above for these lab grade LCR meters. On our Hioki IM3536 for example, there's an entire 13 page Chapter (10.6) dedicated to just accuracy. It's very complex with 5 variables in addition to the DUT measurement parameter and range selected. These variables coefficients are for Level, Measurement Speed, Test Cable Length, DC Bias, and Temperature, and each of these variables coefficients is specified for 7 different frequency ranges from DC to 8MHz.

Best, 
KungFuJosh:
That's all (at least basically 😉) understood, which is why I used SMD resistors on an SMD test fixture. I let the meter run for over an hour before applying correction (manual says at least 30 minutes).

While it's good information, it's not relevant here. The devices are clearly capable of reading 100KΩ at 100kHz and 200kHz:


--- Quote from: luudee on July 09, 2023, 09:46:59 am ---200 KHz: 100.35 KOhm
100 KHz: 100.33 KOhm
 10 KHz: 100.36 KOhm

--- End quote ---

The buggy ST2832 firmware failed at a lot more than just high freq.
ST2832 100KΩ:
100Hz = 49.5052
1kHz = 67.6866
10kHz = 78.2236
100kHz = 98.1972
200kHz = 91.5881
ST2832 100K DCR = 100.057
ST2832 10kΩ @1kHz fail = 6.78268

Same hardware, 100KΩ, switched back to TH2830 firmware:
100Hz = 100.013
1kHz = 100.013
10kHz = 100.005
100kHz = 99.8795
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod