Japanese FET grades (GR, BL, etc).
Henry Pasternack
I'm wondering if someone can give me details on the system of grading
(presumably zero bias drain current) seen on Japanese FETs. I ask this
because Erno Borbely specifies "GR" or "BL" parts in some of his circuits
and I'd like to map these specs into real-world values.
Also, does anyone know a supplier who provides these graded parts?
Thanks.
-Henry
--
ATTENTION! Reply to h...@nortel.ca (hen...@nortel.ca won't work).
Randall Bradley
Actually, Henry, it's worse than that! It's practically impossible
to get JFETs from Toshiba or Hitachi in the US. They seem to
love to sell us appliances, etc., but not JFETs or Mosfets! I dunno
why. So, it's not been easy to get this stuff. Which, BTW, blows,
since those Toshiba JFETs are among the very best. Plus recently
they stopped making some of the most desireable part #'s. Phooey.
some other part numbers apparently have *never* been available in
the US.
I have to buy hundreds to get about 20% to match and sit in my typical
IDSS range. Unless of course the design doesn't care about IDSS or
dumb luck sits it smack dab in the center of the IDSS for a given
batch.
_-_-
BEAR Labzzzzzz
Henry Pasternack
Henry Pasternack (hen...@bnr.ca) wrote:
: I'm wondering if someone can give me details on the system of grading
: (presumably zero bias drain current) seen on Japanese FETs.
Since I received many email replies, I'd just like to thank everyone
who responded. In summary, "GR", "BL", "V", etc., refer to color codes
(green, blue, violet) on the devices themselves, separating them into
difference Idss ranges. The relationship between color and Idss is not
standardized, it seems, but depends on the particular device. "GR" is
the lowest Idss range and "V" is the highest.
Word is it's very hard to obtain these devices pre-sorted from the
manufacturer.
mr...@eden.rutgers.edu
Henry Pasternack wrote:
> I'm wondering if someone can give me details on the system of
> grading
> (presumably zero bias drain current) seen on Japanese FETs. I ask
> this
> because Erno Borbely specifies "GR" or "BL" parts in some of his
> circuits
> and I'd like to map these specs into real-world values.
>
> Also, does anyone know a supplier who provides these graded parts?
>
> Thanks.
>
> -Henry
>
> --
> ATTENTION! Reply to h...@nortel.ca (hen...@nortel.ca won't work).
I thought that the GR and BL grading was only for Japanese bipolar
small signal transistors. If you have particular part numbers I may be
able to get you the information that you need.
mr...@eden.rutgers.edu
Charles Grosjean
hen...@bnr.ca (Henry Pasternack) writes:
>Henry Pasternack (hen...@bnr.ca) wrote:
>: I'm wondering if someone can give me details on the system of grading
>: (presumably zero bias drain current) seen on Japanese FETs.
> Since I received many email replies, I'd just like to thank everyone
>who responded. In summary, "GR", "BL", "V", etc., refer to color codes
>(green, blue, violet) on the devices themselves, separating them into
>difference Idss ranges. The relationship between color and Idss is not
>standardized, it seems, but depends on the particular device. "GR" is
>the lowest Idss range and "V" is the highest.
> Word is it's very hard to obtain these devices pre-sorted from the
>manufacturer.
OTOH, they were never officially supported by Toshiba in the U.S. making
data very difficult to get (although they publish English databooks, for
what market I don't know) and availability through normal channels nearly
impossible. As of several years ago, they were available sporadically from
distributors who specialized in importing Japanese parts. It seems they
were fairly easy to get in Asia though (Taiwan, etc.) although many of the
cool audio parts have been or are in danger of being discontinued.
For the low-noise parts suitable for head amps and preamplifiers, there seem
to be two general categories of color code vs. Idss.
1) GR: 5.0 - 10.0 mA BL: 8.0 - 16.0 mA V: 14.0 - 30.0mA
2) GR: 2.6 - 6.5 mA BL: 6 - 12 mA V: 10 - 20 mA
Category 1 includes parts like the 2SK146/7 and 2SJ72/73. Of 100 2SK146
V (violet) parts that I sorted for a friend, Idss ranged from 18 - 22 mA.
50 2SJ72 BL parts ranged from 9 - 14 mA, and 80 2SK146 GR parts ranged from
6.9 - 7.8 mA. Pair matching was quite good, less than 0.2 mA if I recall
although I didn't test them all. The K146 and J73 parts are interesting in
that they consist of a metal can that contains two plastic parts that have
been matched on the assembly line. With voltage noise hovering around 0.65
nV/rt(Hz) for good parts, they make incredible head amps.
Category 2 includes parts like the 2SK389, and 2SJ109. Unfortunately, I
never had a lot to measure and I didn't pay much attention to the Idss values.
Interestingly enough, my 2SJ109 BL parts were on the high end of the range,
and my 2SK389 V parts were on the low end, but they were also presorted before
being given to me.
I suspect the 2SK369 may be similar to 2SK147 in a smaller package, and easier
to get (I think most of the above parts have been discontinued), but I don't
know of an equivalent part for the 2SJ72.
Hope this helps,
Charles