It is best to take their schedule with a 'grain of salt'. I really DO hope that they will come though. So far, not much.
It is best to take their schedule with a 'grain of salt'. I really DO hope that they will come though. So far, not much.
I'm sure this would have popped up over here soonjohn curl said:
http://www.diyaudio.com/forums/showthread.php?s=&postid=1386592#post1386592
Re: Matched N and P Ch JFETs (Perhaps)
Plans are one thing, ability is another. I asked them about P-ch parts over a year ago--I think I still have the e-mail, so I could check the date if needed. The response at that time was that they hoped to have them in a month or two. The reason cited for the delay was 'yield problems.'
I'm not holding my breath.
I considered joining that buy to get some V parts, but the whole thing smelled a little 'off' to me so I decided to play it safe. It was one of those "if it sounds too good to be true, it usually is" kind of things.
Grey
analog_guy said:
Plans are one thing, ability is another. I asked them about P-ch parts over a year ago--I think I still have the e-mail, so I could check the date if needed. The response at that time was that they hoped to have them in a month or two. The reason cited for the delay was 'yield problems.'
I'm not holding my breath.
flg said:
I'm sure this would have popped up over here soon
I considered joining that buy to get some V parts, but the whole thing smelled a little 'off' to me so I decided to play it safe. It was one of those "if it sounds too good to be true, it usually is" kind of things.
Grey
I think that it is about time that people interested in complementary fet circuits should switch over to Toshiba 2SK170 and 2SJ74 J-fets. There just isn't enough dual units left.
"Matched FETs"
Yep,
I think you are right. I'll just buy a bunch of the Toshiba parts, match them, and then thermally bond them into "matched sets".
Jeff
john curl said:
Yep,
I think you are right. I'll just buy a bunch of the Toshiba parts, match them, and then thermally bond them into "matched sets".
Jeff
john curl said:
Hi John,
How close the match should be? If you have a 2% difference in Idss at one temperature, for the four fets is that enough?
Best regards.
Philippe
Even a 10% difference is probably OK, BUT it usually takes more than 4 parts to get a good match.
The 2SJ74 is no longer listed in the Toshiba parts catalog, so I think it's safe to assume that it's officially discontinued. The 2SK170 is listed, but I suspect it will disappear soon.
There are no low noise P-ch JFETs listed in the Toshiba catalog. In fact, the only through hole P-ch part is the 2SJ103. That's it.
Both the 2SK170 and the 2SJ74 are still available, but I'm betting that it's limited to what's in the pipeline. How many individual units might actually be available is anybody's guess. It's not as many as you might think, though, because the same inventory sloshes back and forth from one seller to another, the price increasing with every transaction.
Grey
There are no low noise P-ch JFETs listed in the Toshiba catalog. In fact, the only through hole P-ch part is the 2SJ103. That's it.
Both the 2SK170 and the 2SJ74 are still available, but I'm betting that it's limited to what's in the pipeline. How many individual units might actually be available is anybody's guess. It's not as many as you might think, though, because the same inventory sloshes back and forth from one seller to another, the price increasing with every transaction.
Grey
GRollins said:
I don't know what "catalog" you are looking at. The JFET's have never been officially imported into the US as there is insufficient demand for them. But if you go to the Japanese website you will find that they still make the 2SJ74:
http://www.semicon.toshiba.co.jp/openb2b/websearch/productDetails.jsp?partKey=2SJ74
The only reason that they discontinued the dual parts was because the physical package was being obsoleted. The single parts are still available, as they use standard TO-92 packages.
Since they are not officially imported by Toshiba USA (TAEC = Toshiba America Electronics Components), you will have to get them through grey market channels. This means somebody like B&D Enterprises who purchase them from a distributor in Japan and resells them here in the US. They may be available more readily in Europe, I don't know.
I don't interpret having the datasheet available as implying that the part is still in production. My guess is that it's to support product that's still in the pipeline. They don't want demand drying up while there are still parts in the warehouse. I do not see any indication as to production status on the page you linked to (in the manner OnSemi does, for instance when they say "Active"). However, the 2SJ74 is not listed in the Toshiba catalog available here:
http://www.semicon.toshiba.co.jp/docs/catalog/en/SCE0004-08_catalog.pdf
I am assuming, perhaps in error, that if Toshiba puts out something called a "Semiconductor General Catalog (Transistors)," and it doesn't list something, then that item is kaput. The date given for the catalog is August, 2007, so it's reasonably current. When they deleted the 2SK389 and 2SJ109, I predicted the demise of the single parts. Now the 2SJ74 is no longer listed and I won't be the least bit surprised if the 2SK170 goes within the next year or two.
I take Toshiba's catalog to mean what it says. Or doesn't say, as the case may be. After all, this is straight from the horse's mouth, not hearsay.
Even if I don't like what the horse is saying...
Grey
http://www.semicon.toshiba.co.jp/docs/catalog/en/SCE0004-08_catalog.pdf
I am assuming, perhaps in error, that if Toshiba puts out something called a "Semiconductor General Catalog (Transistors)," and it doesn't list something, then that item is kaput. The date given for the catalog is August, 2007, so it's reasonably current. When they deleted the 2SK389 and 2SJ109, I predicted the demise of the single parts. Now the 2SJ74 is no longer listed and I won't be the least bit surprised if the 2SK170 goes within the next year or two.
I take Toshiba's catalog to mean what it says. Or doesn't say, as the case may be. After all, this is straight from the horse's mouth, not hearsay.
Even if I don't like what the horse is saying...
Grey
Thanks for the link, Grey. This doesn't look too promising at all. When the dual were discontinued we contacted Toshiba America. They promised to give us end of life notice on the remaining single parts, but we haven't received any such notice from them. I will contact them and find out the status of the 2SJ74. The last official word we heard was as follows:
2SK170-BL
-Non-Promotional package = TO-92.
-No confirmed date for discontinuation.
-No replacement when discontinued
2SJ74-BL
-Non-Promotional package = TO-92.
Probably 2 years at a minimum
-No confirmed date for discontinuation.
-No replacement when discontinued
2SJ103-BL
-Non-Promotional package = TO-92.
Probably 2 years at a minimum
-No confirmed date for discontinuation.
-No replacement when discontinued
2SK246-BL Active, Pb-free version is with a BL(F) suffix
-Non-Promotional package = TO-92.
Probably 2 years at a minimum
-No confirmed date for discontinuation.
-No replacement when discontinued
But that was roughly three years ago. So it is definitely time for a check on the current official status....
2SK170-BL
-Non-Promotional package = TO-92.
-No confirmed date for discontinuation.
-No replacement when discontinued
2SJ74-BL
-Non-Promotional package = TO-92.
Probably 2 years at a minimum
-No confirmed date for discontinuation.
-No replacement when discontinued
2SJ103-BL
-Non-Promotional package = TO-92.
Probably 2 years at a minimum
-No confirmed date for discontinuation.
-No replacement when discontinued
2SK246-BL Active, Pb-free version is with a BL(F) suffix
-Non-Promotional package = TO-92.
Probably 2 years at a minimum
-No confirmed date for discontinuation.
-No replacement when discontinued
But that was roughly three years ago. So it is definitely time for a check on the current official status....
My assumption...and it's only worth what it costs you...is that when they "obsolete" a package, it's because it's through-hole, not because of the body style. I think they're going to go all surface mount. And soon, relatively speaking.
Another guess: I don't think they'll develop/market a replacement low noise JFET, either single or dual, until all existing stock is gone. At a guess, that will be one to three years, minimum. I've tried to stock what I think I'll need over at least that interval. If it's longer, I'll have to scavenge parts from old Japanese receivers or something.
As for Toshiba America, I don't exactly know that they're a font of wisdom. After all, they're the same folks who told me that the 2SK389/2SJ109 didn't exist. Obviously, they can only sell what Toshiba gives them to sell and if they don't give them the dual JFETs, then they won't appear in their spreadsheets or whatever method they use to keep track of stock. But if they don't know the 2SK170/2SJ74s exist, it might never occur to them to send you an e-mail that a nonexistent part (from their point of view) is about to become...well...nonexistent. But perhaps they've become better informed about what the parent corporation has to offer.
Grey
Another guess: I don't think they'll develop/market a replacement low noise JFET, either single or dual, until all existing stock is gone. At a guess, that will be one to three years, minimum. I've tried to stock what I think I'll need over at least that interval. If it's longer, I'll have to scavenge parts from old Japanese receivers or something.
As for Toshiba America, I don't exactly know that they're a font of wisdom. After all, they're the same folks who told me that the 2SK389/2SJ109 didn't exist. Obviously, they can only sell what Toshiba gives them to sell and if they don't give them the dual JFETs, then they won't appear in their spreadsheets or whatever method they use to keep track of stock. But if they don't know the 2SK170/2SJ74s exist, it might never occur to them to send you an e-mail that a nonexistent part (from their point of view) is about to become...well...nonexistent. But perhaps they've become better informed about what the parent corporation has to offer.
Grey
LSK389 and matched P
And the noise levels of their devices is not always within their specified limit. Parts in the same date code show a lot of parameter variability. I'm with John as far as schedule goes.
Best, Chuck Hansen (NOT Charles Hansen of Ayre)
john curl said:
And the noise levels of their devices is not always within their specified limit. Parts in the same date code show a lot of parameter variability. I'm with John as far as schedule goes.
Best, Chuck Hansen (NOT Charles Hansen of Ayre)
(Off topic post)
Hello Mr. Hansen,
Thanks for posting. This is the first time I have noticed your participation here and it is most welcome.
I have a small favor to ask. There exists a lot of confusion surrounding the fact that there are two "Charles Hansen"s in audio. One time I saw that you used "Chuck Hansen" as your byline in an AudioXpress article. Would it be possible to keep that as a standard practice? This might help to reduce the amount of confusion. (I often receive e-mails from friends in the industry congratulating me for your articles!) Thank you for your kind consideration.
Best regards,
Charles Hansen (of Ayre)
Hello Mr. Hansen,
Thanks for posting. This is the first time I have noticed your participation here and it is most welcome.
I have a small favor to ask. There exists a lot of confusion surrounding the fact that there are two "Charles Hansen"s in audio. One time I saw that you used "Chuck Hansen" as your byline in an AudioXpress article. Would it be possible to keep that as a standard practice? This might help to reduce the amount of confusion. (I often receive e-mails from friends in the industry congratulating me for your articles!) Thank you for your kind consideration.
Best regards,
Charles Hansen (of Ayre)
Growing up with my name was a pain in the behumpus. Kids with unusual names get a lot of teasing, quite a bit of it mean-spirited. However, now that I'm older I find that it does keep the confusion down to a minimum. As far as I'm aware, not one person on the planet shares my name.
Now if I could only get them to spell it properly...
Grey
Now if I could only get them to spell it properly...
Grey
Hi Grey -- you're not alone. One of my son's friends is also named Grey, but with a different last name. I've always liked spelling the color with an "e" because I think it looks more sophisticated. So I don't have any trouble with your name!
Odd, but true...
Obviously, my first name is uncommon. I went for years without meeting or even hearing about another Grey (or Gray, for that matter). Then, in the space of a single calendar year back when I was about 20 or so, I met eleven other Grey/Grays...and not another since.
(The story of how I ended up with my name is another matter entirely.)
Grey
Obviously, my first name is uncommon. I went for years without meeting or even hearing about another Grey (or Gray, for that matter). Then, in the space of a single calendar year back when I was about 20 or so, I met eleven other Grey/Grays...and not another since.
(The story of how I ended up with my name is another matter entirely.)
Grey
- Status
- Not open for further replies.