They confirmed already that they are in stock, and I would assume that mouser being a reputable company did buy directly from toshiba and that these a not fakes.
You should order a handful first and determine if they are genuine or not. IF they have a "W" or "M" in the little circle on the curved part of the plastic pak then i would be extremely cautious. Also look out for laser cut part numbers and the 200 pak being blue and saying Malaysia or Thailand.
I just bought a quantity from various Asian suppliers and found that the alleged 2SJ74BL did not look like my NOS 2SJ74 on the curve tracer by any stretch of the imagination.
The alleged 2SK170BL, some of which came from a reputable US source as well, has the same physical appearances as described BUT looked good on the curve tracer. This does not mean that they are real 2SK170 Toshibas.
I have no good way to measure the NF, and that would perhaps be definitive. It was suggested to measure the Rds ON, but I have not done that.
The Idss group did match, fwiw, on both devices.
Left most pic is asian sourced 2SJ74
Right pic is NOS Toshiba.
SAME settings on tracer...
I just bought a quantity from various Asian suppliers and found that the alleged 2SJ74BL did not look like my NOS 2SJ74 on the curve tracer by any stretch of the imagination.
The alleged 2SK170BL, some of which came from a reputable US source as well, has the same physical appearances as described BUT looked good on the curve tracer. This does not mean that they are real 2SK170 Toshibas.
I have no good way to measure the NF, and that would perhaps be definitive. It was suggested to measure the Rds ON, but I have not done that.
The Idss group did match, fwiw, on both devices.
Left most pic is asian sourced 2SJ74
Right pic is NOS Toshiba.
SAME settings on tracer...
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Toshiba ? how can you know its Toshiba who deliver them ?
but again, if loosing 48USD, could have been worse
that is probably the biggest problem
not good to pass them on to other people who cant test them either
imagine what happens if many people begin to build amps with fake jfets, and ....
I'm afraid that a lot of people have already bought these devices from ebay sources, and maybe distributors. For all I know these are actually Toshiba, but perhaps defective dies or other part numbers renumbered. They do look a bit like 2SJ103's curves in the Toshiba book.
But for amps the K170s ought to work just fine, if they have curves like the ones I bought.
The question is for low noise applications or situations where the noise floor starts to effect the minimum distortion spec (ultra low distortion circuits for example).
I am not an expert on the way that devices are packaged or the ins and outs of the business end of this. Just reporting what I have found thus far.
_-_-bear
But for amps the K170s ought to work just fine, if they have curves like the ones I bought.
The question is for low noise applications or situations where the noise floor starts to effect the minimum distortion spec (ultra low distortion circuits for example).
I am not an expert on the way that devices are packaged or the ins and outs of the business end of this. Just reporting what I have found thus far.
_-_-bear
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