At
February 2026, I did remember again this article.

24 hours ago my,
GDS-2102A this succeed to scare me temporarily.
I was testing the scope with my
AWG, at it lowest
Volt/Div 1mV, and the waveform this was not standing at the center of the screen (single channel active).
At display graticule, the sine-wave appeared lower than it should.
At higher Volt/Div, and higher signal amplitude, everything looked normal.
Oh no, my scope when out of calibration. 
The problem shown with input of 3mV-PP / 1mV RMS 50Hz sine-wave.
Today that I was calm, I did activate and run
Vertical calibration and
SPC (Signal Path Compensation) calibration.
And this automated miracle, it did fix my scope.
I did share the output of my AWG at both channels with BNC cables, both channels these was measuring identically down to the last digit.
Then added the probes, and tested the scope test source 1KHz (probes calibration).
Everything looked good but measurements was not that precisely identical.
Then I did use my AWG again, this be the source of the signal directly at both oscilloscope inputs.
Aha moment, measuring precision this is restored.

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GDS-2000A Series this
hides a secret, GDS-2000A series this using as main processor the chip of
Analogue Devices ADSP-BF531Due this hardware,
GW Instek succeed DC gain accuracy: ±(
3% × |Readout| + 0.1div + 1mV) when
2mV/div or greater is selected.
As soon GW Instek this adopted
Xilinx’s Zynq-7000, this earned few added functions, improved FFT etc etc, but DC gain accuracy
this downgraded to 5% at lowest input signal.
Tektronix marketing when mad at 2013, Christopher J Loberg - Tektronix, he wrote
a hilarious Competitive Fact Sheet.
That Tektronix this measured the GDS-2000A and this had ±27% of error, with 12mV PP signal.
12mV PP signal this is 4mV RMS, Tektronix was scared to measure with their
MSO/DPO2000B Series anything less than 4mV RMS.

Nothing of all these they have a significant importance,
if you never connect to your scope a high precision AC/DC current probe.Such a probe this is a source mV/A, this translates that a scope with
crippled sensitivity, and with out
tight accuracy, this will sabotage your measurements of low current.
PICO TA-189, this is an excellent European probe 30A 100mV/A.
The ideal scope for it, this would be a GDS-2000A series,
with additional V/Div of 0.5mV.
Even in 2026,
GW Instek this failed to provide such an instrument.
While
R&S Germany, they asking
15.000 Euros, for a scope with
V/Div of 0.5mV.
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Today I am overloaded with experiences, about what my scope can do at the bandwidth of 50/60Hz, that we electricians using.
Measuring of voltage, its easy (due active isolated voltage probe).
Measuring of low current, this is difficult but possible, due this PICO TA-189.
Measuring of power due waveforms phase-shift, this requires an far more advanced main processor.
Measuring of power with an oscilloscope, this has purely educational value, and I am not a school boy any more.
My scope this is now 13 years old, and because the development of medium priced scopes with better accuracy this has stopped, I am currently do not feel the need so to buy a fresher one.
If a bit cleaner waveform at low current, this comes for a price of 15.000 Euros? Then I prefer to never see it.
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Attached screenshots of my latest tests.
It does seems as weird to me, that voltage precision this can be that much influenced between of two identical probes.
GDS-2000A calibration source at the back, this uses BNC.
AWG as source, this also connects due BNC.
If there is a learning, from all of these tests, my pair of probes, they are not that perfectly matched, production issue or other (product aging ?) of Pintek Taiwan.