If you read Chinese (maybe with help of Google or DeepL), there (
https://www.kechuang.org/t/89682) is some characterization of the temperature coefficient of RJ711 samples.
the link is pretty long.
You can short them by yourself when you cut them befor the first "?"
The rest ist your Userinfo an your searchhistory.
Eample:
https://www.ebay.com/itm/225680041292
RJ711 on Aliexpress have values of more than 100 kOhms. Which is very suspicious for foil resistors.
RJ711 on Aliexpress have values of more than 100 kOhms. Which is very suspicious for foil resistors.
The specifications indicate that resistance values up to 800KΩ can be produced.
The really high resistance values are only available for the higher power versions - possibly internal multiple smaller elements in series.
Just because Vishay normally only offer up to 50 K as standard values does not mean the Chinese could not use larger elements or similar. At a higher price one also gets higher resistance values from Vishay.
The one paper on the temperature cuves shows rather little linear temperature dependence, with a rather low 2nd order TC. In this respect they get close to Vishay's Z foil. However there seems to be quite some spead in the linear TC. So some are good and some are not that good. One may have to look at the fine print, exact type selection.
In many cases the relevant parameter is anyway not the TC, but long term stability.
When getting parts via a channel like Aliexpress / Ebay there is still the chance of getting fakes - just because the original part is from China does not mean there could be no fakes from China too.
Metal foil resistor beyond 50 kohm is of cause feasible, here is an example of 165 kohm AE TLC resistor.