I have 1 of these generic ebay testers, from ~2017, IDK what chip, but with the big 2*4" screen or so.
But recently I took off a sot23 SMD part, marked as NAN, and the tester said it was a JFET, but with no negative rail, it said Vgsoff was like 63.2V and Idss was 2.8mA or something like that.
This thing seemed to check mosfets ok. Has anyone ever had a MOSFET read as a JFET on 1 of these testers?
Going by the pinot the tester said, I checked it with a dual PSU and it seemed to turn on at about -1.8Vgs, as I headed towards Vgs=0V, and at Vgs=0, it seemed to have an Idss of 10-20mA, with a 1k res. on the drain to Vdd, but with Vdd going past 23V, I seemed to have zapped it somehow.
more details below
https://www.eevblog.com/forum/repair/what-is-this-jfet-and-whats-its-purpose/msg4913053/#msg4913053But I'm not sure if it was really a JFET, although if the tester pinout was correct, it never had any gate current, until I fired it a bit.