Discontinuation of 2SJ74 and 2SK170 - diyAudio
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Old 14th March 2008, 01:19 AM   #1
Ruach is offline Ruach  Singapore
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Default Discontinuation of 2SJ74 and 2SK170

I was recently informed by Toshiba that the 2SJ74 JFET will be discontinued this year. There will not be a replacement.

My supplier has also unofficially hinted that the 2SK170 may be discontinued by next year.

FYI
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Old 14th March 2008, 02:28 AM   #2
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I realized this last year. The 2SJ74 is already gone. It was not in the main Toshiba catalog dated (I think) last August.
There are a considerable number of parts still in the distribution pipeline, so it's not necessary to panic. They'll be available for a while yet.

Grey
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Old 16th March 2008, 03:36 AM   #3
fab is offline fab  Canada
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Hi

But they were great devices.
Is there any substitute that you know?

Thanks
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Old 16th March 2008, 12:12 PM   #4
MRupp is offline MRupp  Germany
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Quote:
Is there any substitute that you know?
As has been mentioned before in this forum: 2SK370 / 2SJ108 - seemingly the same chip in a different package. Unless they become obsolete too.
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Martin Rupp
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Old 16th March 2008, 12:14 PM   #5
poynton is offline poynton  United Kingdom
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Default Re: Discontinuation of 2SJ74 and 2SK170

Quote:
Originally posted by Ruach
I was recently informed by Toshiba that the 2SJ74 JFET will be discontinued this year. There will not be a replacement.

My supplier has also unofficially hinted that the 2SK170 may be discontinued by next year.

FYI

So what was the last date code of the genuine article ?
No doubt they will be faked!!
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Old 16th March 2008, 02:24 PM   #6
fab is offline fab  Canada
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Quote:
Originally posted by MRupp


As has been mentioned before in this forum: 2SK370 / 2SJ108 - seemingly the same chip in a different package. Unless they become obsolete too.
Thanks

Except for 400mW max power dissipation for 2SK170 compared to 200mW for 2SK370, I can not see other difference at first sight.
So why the 2SK170 is obsolete and not the 2SK370?
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Old 16th March 2008, 04:03 PM   #7
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This is all old news, but for whatever reason it catches fire again from time to time.
There are no Toshiba low noise P-ch JFETs in production.
The 2SK170 is current through some time this spring--I forget the exact date. The 2SK389 has been gone for quite some time.
There is product in the retail pipeline, so you will be able to buy parts for a while yet.
As for why, I've not seen any formal reasons from Toshiba, but my working hypothesis is that they regard through-hole parts as obsolete and are eliminating all through-hole parts from their catalog. The answer to your next question is no...I do not know of any plans to produce surface mount low noise JFETs in the near future.
Try to be rational about this. I've seen people who won't use ten parts in their entire lifetime talking about buying a hundred, "Just in case!" Just in case of what? Martians land next door and demand that the DIYer build them a fratzenwhoosis so they can call home? Rather than panic and start hording parts you will never use, sit down and make a list of the things you might actually build and buy accordingly.

Grey
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Old 16th March 2008, 04:31 PM   #8
EUVL is offline EUVL  Europe
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> Except for 400mW max power dissipation for 2SK170 compared to 200mW for 2SK370, I can not see other difference at first sight.
So why the 2SK170 is obsolete and not the 2SK370?

Because you can now make the same transistor on half the die size with advanced lithographic processes, and hence twice the number of transistors per wafer, and hence half the cost / die. The penalty -- half the dissipation because of reduced die area for heat transfer. But I guess the transistor still sells for the same price, and most people could do with 200mW. So it makes sense for Toshiba.

And as far as I know, 2SJ108 is active.


Patrick
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Old 16th March 2008, 06:42 PM   #9
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Look at the offerings from Linear Systems.
The specs on their parts meet or exceed those of similar Toshiba parts.
The bad news -- the LS distributors are small and unlikely to sell these parts in small quantities. They are also a bit pricey.

ZAP
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Old 17th March 2008, 12:34 AM   #10
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I was able to purchase some 170s and 389s from Linear Systems distributors.

Too bad they don't make / sell the P-channel fets.
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