Happy to read your feedback here.
As the official EEVBlog distributor, we now also have the 121GW available for purchase in Europe:
https://www.welectron.com/EEVBlog-121GW-Data-Logging-Multimeter-with-Bluetooth
My review of the meter: https://lygte-info.dk/review/DMMEEVBlog%20121GW%20UK.html
Having an input impedance as low as ca 2 kOhm for frequency measurement makes limiting for many things. For example measuring the frequency at different points of a 555 timer (or other oscillator) circuit without knowing about the low impedance could result in many strange readings (different frequency at different points, since the meter would affect the circuit by a lot).
Is there any uncertainty? Something you can't take into account while measuring?
I have reported https://www.eevblog.com/forum/testgear/eevblog-121gw-discussion-thread/msg1687298/#msg1687298. that the 50MOhm range of my new 121GW was out of specification, by 1.4 ..2%.
Today, I have re-adjusted this range.
At first, the manual was wrong, as a 50 MOhm reference resistor is required, instead of a 40 MOhm one.
Then, due to higher leakage currents over protection diodes at 50 MOhm, compared to 10 or 20 MOhm, this range is quite non-linear, like I have found with my BM869.
So the readings at 10M and 19M are about 0.2% higher than nominal, when the 121GW is correctly calibrated at 50.000MOhm.
To compensate for this effect, it makes sense to use a 50.05 MOhm reference instead, so that at 50MOhm, the nominal reading is 0.1% low, but at lower values, like 10MOhm, the reading is only 0.1% high.
So the 50MOhm range is now very precise and stable, and also is not affected by mains disturbances.
The 5MOhm range though, is noisy, due to lacking 50/60Hz suppression, and probably a missing filter capacitor.
I could silence this range, even with strong interference from mains, by a parallel low leakage foil capacitor, 100nF, MKP.
I still hope for FW change by UEI, to correct both features.
Frank
Dr Frank, if you have a way to run some sort of temperature study on this meter, I would be very interested in seeing you install TPW_rules's patched version of 1.02 and trying it out. The prototype has always drifted pretty badly which I assume is why they changed the reference circuit. It sounds like you are already trying to find the sweet spots to use for the alignment to bring it in tighter. I wonder how the TC matches what is specified in the manual.
I just received tracking info for mine, and am about to leave on vacation for 2 weeks >_<
Anyone got an idea how to arrange this with DHL, or will it just end up going back to sender, and i'll have to arrange a next shipment?
A bit impractical to just send them out in the middle of holiday season without asking if people can receive it
FYI, Welectron in Germany have some meters in stock:
https://www.welectron.com/EEVBlog-121GW-Data-Logging-Multimeter-with-Bluetooth
FYI, Welectron in Germany have some meters in stock:
https://www.welectron.com/EEVBlog-121GW-Data-Logging-Multimeter-with-Bluetooth
I ordered one from Welectron.Good that there are suppliers wihin the European trade zone.
I received shipping notification yesterday.
The most sensitive part appears to be the HY3131 itself. I'm not making the part even warm enough to detect the change in temp with my fingers.
To be clear, I do not have the current version of the meter. Any idea how much "way off" is and what modes? Could you post some details?
Are you maybe heating up a PTC? What range(s) and how long until things go back to normal?
How to make the meter show weird readings:
1. Put the meter on the Low Z range
2. Measure the mains voltage (let's say 120.0 V AC)
3. Put the meter on the Resistance range
4. Short the probes
You may observe an anomalous reading of about 3 ohms, slowly declining towards zero.
On other ranges (like DC mV) you may observe anomalous readings too.
It's as if a capacitor is charged up and is taking time to discharge back to zero volts. (Or did something heat up and it's taking time to cool down?)
FYI, Welectron in Germany have some meters in stock:
https://www.welectron.com/EEVBlog-121GW-Data-Logging-Multimeter-with-Bluetooth
I ordered one from Welectron.Good that there are suppliers wihin the European trade zone.
I received shipping notification yesterday.Good for you! Mine is still in Frankfurt since August 1 "Arrived at transit facility"