I've purchased a lot of 100 2N5457 JFETs from a chinese supplier on ebay for a 1176 project I'm currently working on. After trying about 20 of those to find matched pairs, I've found that they all have about the same cutoff voltage of -0.45 Volts with one exception - this one had -0.53 Volts. According to the datasheet, Vgs(off) of the 2N5457 ranges from -0.5 to -6 Volts. What puzzles me, is that they all are the same. Usually, FETs are supposed to vary a lot more and the offer on ebay didn't imply they were MATCHED parts.
They - kinda - work in the circuit. Calibrating the unit is not as straightforward as I am used to from another 1176 I've built - maybe it's the lowish cutoff voltage giving me trouble. And as soon as the compression kicks in, the signal becomes pretty noisy. Again, I haven't seen this before.
My component tester thinks, these are NPNs with a HFE of 24.000 (24 thousand!!) Is there anything else I can test to see if they are genuine parts?
They - kinda - work in the circuit. Calibrating the unit is not as straightforward as I am used to from another 1176 I've built - maybe it's the lowish cutoff voltage giving me trouble. And as soon as the compression kicks in, the signal becomes pretty noisy. Again, I haven't seen this before.
My component tester thinks, these are NPNs with a HFE of 24.000 (24 thousand!!) Is there anything else I can test to see if they are genuine parts?