Replacement For Toshiba 2SK170/2SJ74

[Mark Johnson]

"The Art Of Electronics" has VERY flattering things to say about the J107. Which is one reason why I bought 500 of them a few years ago.

 

[EUVL]

> "The Art Of Electronics" has VERY flattering things to say about the J107.

With an Idss of min 100mA ?


Patrick

 

[tiefbassuebertr]

As I point out in another thread, you can use the Gr grades with much the same quality, and with little or no adjustment. Also you can use the Linear systems parts, including their a grade.

Much of the cost of some of these parts is due to audio guys wanting perfect matching, which is usually not necessary. In addition there are some cheaper surface mount parts.

Finally you can use parts like J113 and J176 which do not have as high a transconductance or low distortion or noise, but which will can still sound good and are cheap. Members here will probably mention their own alternatives.

page 7-35 and 7-37 under
https://www.google.de/url?sa=t&rct=...Databook.pdf&usg=AOvVaw3d9hb1R-bK3U4hF_dGcY1J
shows approaches to increase gm. Also the attached files. Lowering C-in (C g-s) provide better sonic results - so I think.

 

[jean-paul]

Mmmm.....

 

[WalterW]

1 should be |

 

[nr12]

I read the marking "ok" so it must be fine.

 

[Soundhappy]

And number seven this shape :

 

[jean-paul]

Hi I had many original 2SK170BL and 2SJ74GR and found a “new” source. I am inclined to call these 2SK170GR either relabeled or fake.

Positive is that when I compared with original 2SK170 from my stock I found a sealed bag with new 2SK30 And a bag of TDA1514 (the amplifier). Both keep turning up.

 

[Skylar88]

And number seven this shape :

Yes. Like this one in my stash.

 

[Michael Chua]

And a bag of TDA1514 (the amplifier).

Hi jean-paul

If you like to sell your TDA1514, PM me.

Regards
Mike

 

[tiefbassuebertr]

"The Art Of Electronics" has VERY flattering things to say about the J107. Which is one reason why I bought 500 of them a few years ago.

Which things and on this pages ? - go to page 131-219 under
The Art Of Electronics 3rd Edition : Paul Horowitz, Winfield Hill : Free Download, Borrow, and Streaming : Internet Archive
(ckick on "PDF")

 

[McQuaide]

Anyone know what the little metal caps are that Punkydawgs ships with Jfets?

 

[exojam]

I asked him the same exact question; they are for heat dispersion (a little heat sink).

 

[McQuaide]

Like this I assume with some paste.

 

[BesPav]

Anyone know what the little metal caps are that Punkydawgs ships with Jfets?

For easy of thermal coupling.

 

[mlloyd1]

in my paper edition of AoE, the page numbers you list are far too low to find what you seek.

Which things and on this pages ? - go to page 131-219 under
The Art Of Electronics 3rd Edition : Paul Horowitz, Winfield Hill : Free Download, Borrow, and Streaming : Internet Archive
(ckick on "PDF")

 

[Zung]

Some additional data points: I recently ordered 10 pairs of J74/K170 just to see how fake fakes can be, apart from the lettering.
I received 10 pcs J74, complained to seller, and promptly received the full refund, so nothing to complain about.
Nevertheless, I tested them using EUVL's jig, Vd=9Vdc and Vg=50mVac:

The moral:

• Idss is within specs
• Yfs is only half of the nominal 22mS
• The dispersion of the parameters is minimal, I don't know how they do it; quite remarkable

So, they probably are useful for something, maybe some line-level stuff

Btw, don't worry about the white paint, I tippex them so I can write on them with a sharpie.

 

[EUVL]

Yfs for 2SJ74BL at 10mA is 40mS.
So miles out.

And then you should also measure noise.
Because that is what you pay for.
Else just buy J17x.


Patrick

 

[Zung]

There's some discrepancies within Toshiba' datasheet: the table says 22mS Typ., and the graph indicates 40mS as you said.
Anyway, 10mS is OK-ish in a lot of applications, for $0.50 a piece.

 

[EUVL]

~40mS is also what I measured, from thousands.
10mS is 100R Zout in follow mode.

As I said, decisive is not (only) Yfs, but noise.


Patrick