100mS@50mA. Datasheets for all of these (plus a lot of non-complementary ones) here: http://www.semicon.toshiba.co.jp/eng/index.htmlwrenchone said:
So they are. Serves me right for assuming that devices listed in the JFET section are actually JFETs🙄 I was wondering why they were enhancement mode.
Looking over the datasheets some more, of particular interest to me are 2SK246/2SJ103 and the similar 2SK330/2SJ105, being the cheapest I can get hold of, and rated at 50V. The have lower input capacitance than 2SK170/2SJ74, but lower Yfs. Also 2SK364/2SJ104, which are very similar to 2SK170/2SJ74.
I wouldn't mind obtaining some Spice models for these, if anyone has any.
Looking over the datasheets some more, of particular interest to me are 2SK246/2SJ103 and the similar 2SK330/2SJ105, being the cheapest I can get hold of, and rated at 50V. The have lower input capacitance than 2SK170/2SJ74, but lower Yfs. Also 2SK364/2SJ104, which are very similar to 2SK170/2SJ74.
I wouldn't mind obtaining some Spice models for these, if anyone has any.
quote:
regarding 2SK147:
there are better devices out there (2SK369)
Actually the 2sk147 and the 2sk369 are the same devices but in different packages. The old 2sk147 was in a tall TO-92MOD package and the 2sk369 is in a standard TO-92. Power dissipation is less; 400 mW for the TO-92 and 600mW for the
TO-92MOD
regarding 2SK147:
there are better devices out there (2SK369)
Actually the 2sk147 and the 2sk369 are the same devices but in different packages. The old 2sk147 was in a tall TO-92MOD package and the 2sk369 is in a standard TO-92. Power dissipation is less; 400 mW for the TO-92 and 600mW for the
TO-92MOD
If anyone's still interested, I bought a bunch of 2SK246 and 2SJ103 and have been testing them out.
Unfortunately I could only get ones from different Idss bins, so they're of limited use as complementary pairs, but they're still useful. Low gain means they're not so good for things like differential stages, but they're great for cascodes (also helped by high Vpo), currents sources and anything else that doesn't require high gain. Low input capacitance should make them a good choice for anything that needs speed. 50V rating is nice compared to only 25V for 2SJ74.
Unfortunately I could only get ones from different Idss bins, so they're of limited use as complementary pairs, but they're still useful. Low gain means they're not so good for things like differential stages, but they're great for cascodes (also helped by high Vpo), currents sources and anything else that doesn't require high gain. Low input capacitance should make them a good choice for anything that needs speed. 50V rating is nice compared to only 25V for 2SJ74.
2sk982
Has anyone tested it for audio means? Datasheet claims gm 100 min.,
but no noise figures are given.
Rüdiger
Has anyone tested it for audio means? Datasheet claims gm 100 min.,
but no noise figures are given.
Rüdiger
These are great parts, large pinch-off voltage kind; good use for CCS and cascodes and the likes. Borbely used them a lot.
For other applications (gain stages) they have a little too low gm, generally.
Hannes
Hi everyone,
it seems like the JFETS are all almost extinct.
Do you know of any JFETs that are still in production and are worth considering for audio applications? (Other than the Toshiba clones LSK170 and LSJ74 by Linear Systems).
What is the reason that they are almost all gone? Too costy production? No demand for them?
Thanks
poli
it seems like the JFETS are all almost extinct.
Do you know of any JFETs that are still in production and are worth considering for audio applications? (Other than the Toshiba clones LSK170 and LSJ74 by Linear Systems).
What is the reason that they are almost all gone? Too costy production? No demand for them?
Thanks
poli
The BF862 shows up in projects from time to time. People who have done measurements say it has good to excellent performance, even though it is NOT characterized for audio use. (It's intended as an RF amp in AM broadcast radios.)
http://www.nxp.com/documents/data_sheet/BF862.pdf
The reason I've heard most often is lack of demand, which really comes down to the JFET's being more costly than alternatives.
Dale
Jets might still have a life in power amps where the source impedance of a passive attenuator/pot raises distortion. Low Gm is not so much a problem if you just look at how much better amplifier design has become for instance Ostripper's long threads. In some ways it may actually be an advantage.
Also, I have heard about some Jfets that weren't mentioned: the LSK489 which is like a low-noise version of the BF844, and the 2N4416.
Also, I have heard about some Jfets that weren't mentioned: the LSK489 which is like a low-noise version of the BF844, and the 2N4416.
Last edited:
There are hundreds of jFETs still in production from dozens of manufacturers.
Nchannel are easy to get, Pchannel are less easy.
Complements are less easy.
High gm, low noise are less easy.
But if you can design with Nchannel medium to low gm, you have hundreds to choose from.
BF862 Highly Recommended
I have been using BF862 JFETs in place of the 2sk170 for a couple of years now. They are SOT-23 SMD components, but I have no problem soldering them.
The best performance is obtained if the Vds is no more than about 9.3Volts and are run at 60-90% of Idss. I always use a 470 ohm gate resistor (Susumu RG) to eliminate any possible oscillation. The sound of the BF862 is neutral, transparent and detailed. It lets the musicality of other hifi components come through.
Like the 2sk170, the Bf862 Idss varies considerably within the same lot. Consecutive BF862s in the same "ammo belt" can vary up to +/- 25% from one component to the next. In fact in a strip of 100 BF862s it appears that they come from 2-5 different production lots that are mixed together. I have a breadboard for testing SOT-23 JFETs.
I have been using BF862 JFETs in place of the 2sk170 for a couple of years now. They are SOT-23 SMD components, but I have no problem soldering them.
The best performance is obtained if the Vds is no more than about 9.3Volts and are run at 60-90% of Idss. I always use a 470 ohm gate resistor (Susumu RG) to eliminate any possible oscillation. The sound of the BF862 is neutral, transparent and detailed. It lets the musicality of other hifi components come through.
Like the 2sk170, the Bf862 Idss varies considerably within the same lot. Consecutive BF862s in the same "ammo belt" can vary up to +/- 25% from one component to the next. In fact in a strip of 100 BF862s it appears that they come from 2-5 different production lots that are mixed together. I have a breadboard for testing SOT-23 JFETs.
Most were very noisy due to trapped charge under the gate.
The low noise RF dual gates are no longer made
There is a comment by Johnc on forthcoming lower noise mosFETs in another Thread.
http://www.diyaudio.com/forums/analogue-source/287439-bews-ne5534-phono-preamp-2.html#post4631341
http://www.diyaudio.com/forums/analogue-source/287439-bews-ne5534-phono-preamp-2.html#post4631341
Last edited:
- Status
- Not open for further replies.