Which parameters I should pay attention to it?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.
I just bought a pcb from diyaudiostore and found out the problem of finding 2SJ109. Is there any replacement I can use? I'm making a BA-1 as a pre only.
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.
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.
Is this really the best advice you can give?
Probably.............Is this really the best advice you can give?
OK will not try my best to findMaybe 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.
I think 2sj74 is not easy to find tooA 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?
Will try my best to findOK will not try my best to find
I think 2sj74 is not easy to find too
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 :diyaudio store has the lsj parts but not matched....
J74/J74 Stereo Differential Kit – diyAudio Store
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.Where are you going to find any grades of 2sj109?
I have few 20pcs 2sk170bl with me. I measured it using Nelson method. Simple one with a resistor. I got few matches very closely. Not sure I'm measured it in right way or not. Measuring the voltage across a resistor.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.
1.3xx maI'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.
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