the j174 is a Pchannel jFET.
Try the search engines in digi/mouse/rapid for P jFETs and see which ones are in stock with similar parameters.
Try the search engines in digi/mouse/rapid for P jFETs and see which ones are in stock with similar parameters.
Maybe Idss between 50% and 200% of the lsk74.
Maybe Vp between 100% and 250% of lsk74.
Then build up a simple test jig and measure noise.
Maybe Vp between 100% and 250% of lsk74.
Then build up a simple test jig and measure noise.
A 2sj109 is almost impossible to find these days. You can buy 2 matched 2sj74 and use them. A 2sj109 is more or less made of 2 2sj74 in the same chip. There is information on the forums where to buy them from trusted sources and how to install them on the boards.
Is this really the best advice you can give? 🙄
diyaudio store has the lsj parts but not matched.
You can buy them matched at fetaudio and also on ebay. there is a recomended seller which has genuine parts.
As I said, searching around the forums will give you alot of answers.
And as many have stated before me, the 2sk170 and 2sj74, were some of the lowest noise transistors available and while there are currently available parts with similar specs they are a compromise in one way or another.
You were looking at the wrong offer. Here is the link for 4 pcs (2 matched pairs) of LSJ74 Grade B, comparable to 2SJ74 Grade BL :
J74/J74 Stereo Differential Kit – diyAudio Store
For making a BA-1 pre, what grade should I use for 2SJ109? Refer to Toshiba datasheet, there are grade GR, BL and V. Which one is the best choice?
My little town here. Just trying my luck. My town here there are few shops over 40 years old. Just trying my luck. Need to know what I'm looking before I walk in.
BL grade.
More important that that, is to find 2SK170BL and use ones with about 8ma Idss for the CCS (Q202).
That will properly set the operating point of the differential pair.
More important that that, is to find 2SK170BL and use ones with about 8ma Idss for the CCS (Q202).
That will properly set the operating point of the differential pair.
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That's a perfectly good way to measure.
You can also use 9v battery and multimeter set to mA, it's very easy -
You can also use 9v battery and multimeter set to mA, it's very easy -
I'm measuring similar like yours but your diagram missing a resistor.
Few years ago I bought some 2sk170bl from RS component which I still had it now. The reading is about 1.3xx, seems this is too high.
Few years ago I bought some 2sk170bl from RS component which I still had it now. The reading is about 1.3xx, seems this is too high.