The Y's are unavailable, period.
You might mangle the 2SK170Y out of obsolete equipment, the 2SJ74Y are cast in the everlasting black hole. Another period.
You might mangle the 2SK170Y out of obsolete equipment, the 2SJ74Y are cast in the everlasting black hole. Another period.
It is in the originals, but I've to do a lookup in my brittle papyrus rolls to find them.
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So the options are:
- redesign
- parallel current sinks (or sources from the plus proper)
- bjt input
- give up (no Y's)
- invent eq's (dropmeanote, @xtrm high cost possible)
I thought I did an edit, but a post appeared...
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I have a BL grade(operate at 2.3mA.) and I changed the values of the resistors to stay as close as possible to the original operating points. I didn't find Y grade anywhere.
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Check the 1983 data book (it's been linked to round these parts multiple times already).
Keep an eye on Yafuoku (and be prepared to pay through the nose
). But given the Y's are 1-3mA, finding ones at 1.3mA in particular may complicate the matters a wee bit. Alternatively, you could give 2SJ44K / 2SK163K a try - while their Yfs is ~1/3 lower, they are *much* easier to find (even in quantity for matching purposes), low noise, and - supposedly - truly complementary (which the Toshiba's aren't).
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Found a site to maybe buy Y-grade jfets.
A supplier from the Digikey site.
Utsource is distributor of 2SJ74Y , buy 2SJ74Y , in stock, new&original with lower price, offer image datasheet|pdf
Utsource is distributor of 2SK170Y , buy 2SK170Y , in stock, new&original with lower price, offer image datasheet|pdf
Waiting for a respons on monday on those.
Something I missed or beeing fooled you think?
A supplier from the Digikey site.
Utsource is distributor of 2SJ74Y , buy 2SJ74Y , in stock, new&original with lower price, offer image datasheet|pdf
Utsource is distributor of 2SK170Y , buy 2SK170Y , in stock, new&original with lower price, offer image datasheet|pdf
Waiting for a respons on monday on those.
Something I missed or beeing fooled you think?
Check the 1983 data book (it's been linked to round these parts multiple times already).
Keep an eye on Yafuoku (and be prepared to pay through the nose
Alternatively, you could give 2SJ44K / 2SK163K a try - while their Yfs is ~1/3 lower, they are *much* easier to find (even in quantity for matching purposes), low noise, and - supposedly - truly complementary (which the Toshiba's aren't).
Thanks alot, I have sent some mail requests for 2SJ44K/2SK163K but most of them are not K-grade out there.
I bought some of the K grade NEC transistors from Wakamatsu in Japan a year or so ago, and they still have hundreds in stock. At that time, Tokyo Adcom also had plenty in stock, but Wakamatsu came out cheaper. (Not sure though if either of those companies can / will communicate in anything else but Japanese.)
J44 / K163 also pop up on Yafuoku every now and then - even matched pairs...
BTW, K163 was later replaced by K523 (identical specs) and K533 (lower IGSS, 100pA vs. 1nA, otherwise identical), which may simplify the search. No alternative for J44, as far as I know.
RE Utsource: I've seen their name mentioned in several threads about fake components here, so I personally would not trust them. On the other hand, most people don't even know a Y grade of J74 / K170 existed - the internets are full of counterfeit GR, BL & V parts, but I've never seen a single J74Y or K170Y listed on eBay and such. People don't know about them = no demand = no fakes. Hence, there might be a minuscule chance Utsource have the real deal... but I somehow doubt it.
J44 / K163 also pop up on Yafuoku every now and then - even matched pairs...
BTW, K163 was later replaced by K523 (identical specs) and K533 (lower IGSS, 100pA vs. 1nA, otherwise identical), which may simplify the search. No alternative for J44, as far as I know.
RE Utsource: I've seen their name mentioned in several threads about fake components here, so I personally would not trust them. On the other hand, most people don't even know a Y grade of J74 / K170 existed - the internets are full of counterfeit GR, BL & V parts, but I've never seen a single J74Y or K170Y listed on eBay and such. People don't know about them = no demand = no fakes. Hence, there might be a minuscule chance Utsource have the real deal... but I somehow doubt it.
I thought those were self-explanatory (well, perhaps not Tokyo Adcom).
Yafuoku is of course auctions.yahoo.co.jp - no listings for J74Y or K170Y right now though. The key is to set up email alerts and be patient.
Wakamatsu is wakamatsu.co.jp, J44K here, K163K here.
Tokyo Adcom search page is here...
Yafuoku is of course auctions.yahoo.co.jp - no listings for J74Y or K170Y right now though. The key is to set up email alerts and be patient.
Wakamatsu is wakamatsu.co.jp, J44K here, K163K here.
Tokyo Adcom search page is here...
BTW, where does the 1.3mA figure come from? (Post #1181, perhaps?)
Unless I'm mistaken (and I quite often am
), the 1.3mA is not the IDSS of the JFET itself, but rather the ID an average Y grade JFET (IDSS ~2mA) would pass when degenerated by 50R (1/2 of the 100R trimmer). Which would mean that a JFET from the very bottom of the GR grade range (IDSS ~2.6mA) should get you pretty close to the target.A trusted seller of the Toshiba JFETs and a member of this board, alweit, used to be able to supply the lowest possible IDSS GR grade parts specifically for Le Monstre builds in the past - not sure if he still has some available, but there's no harm in asking...
