I've come into a few hundred 2SK389s as well as few hundred 2SJ109s. I want to try to match them up and then sell the pairs on Ebay.
I've done JFET matching before but not with IDSS method. What I have done, for sensor applications, is measure the VGS for both sides of the FET at the bias point, or very close to it, of the final circuit.
What is typical bias point for audio applications? I was thinking 9V and 5ma, but I really have no idea.
I've done JFET matching before but not with IDSS method. What I have done, for sensor applications, is measure the VGS for both sides of the FET at the bias point, or very close to it, of the final circuit.
What is typical bias point for audio applications? I was thinking 9V and 5ma, but I really have no idea.
All the noise data suggests 1mA and source impedance of between 10k and 100k is optimal for noise performance, so that would be typical I expect. There's little point spending money on a low-noise part and then running it well away from its best noise performance.
check out this thread:
https://www.diyaudio.com/community/...k170-2sj74-2sk389-2sj109.413422/#post-7698859
https://www.diyaudio.com/community/...k170-2sj74-2sk389-2sj109.413422/#post-7698859