Then it means that the only possible calibration data in the EEPROM are the parasitic capacitance, resistance and inductance that are stored when press CLEAR... And if so I'll live with it... It's no big deal to press CLEAR at every turn on... Considering the TH2822C price...
It looks like that, but I have no way to confirm it. I tried several capacitors and inductors (the best ones I could get my hand on) and got very close results in 10kHz and 100kHz (after a CLEAR open and CLEAR short process).
I didn't understand exactly... When you power the meter on with the modified EEPROM, it boots at 100 Khz... And then if you press the FREQ button what happens ? I have the TH2822 (so only 1 Khz)... That means that if I want to switch between 10 Khz and 100 Khz I have to rewrite the EEPROM ? Because that is a real pain...
In the case of your model ask vtl for details, he got the same one. What I understood, he could only get 10kHz or 100kHz on power up, when pressing FREQ button it would go back to 100Hz in both cases. However a more sophisticated hack using a EEPROM with a "page select" pin (if they exist) could work to select 10kHz power up or 100kHz power up.
I have faith that there's a magic word on the first 2 bytes of the eeprom that will copy the model information from the EEPROM to the MCU, and maybe perform some autocal process to write to EEPROM those data that I think is the default CLEAR open and CLEAR short for each frequency.
I am not very knowledgeable in the measurement process but I think it relies on the theta between voltage and current to determine if it's a cap or an inductor, and it's value. So the real "calibration" would be a timing accuracy issue I think. But again, I'm no one to assume that.
By now I've stopped researching any further hack, couldn't find anything else, but I'm looking forward to get some time to continue searching for a way to do it.
What I did to my meter is write to the eeprom the power up settings I like, solder it and have the WP pin high (write protected) so by accident I could not rewrite it by going to the UTIL menu. It works without problems.