Well, one can design with SE or Differential, no complimentary, and use Tosh 2SK209 and be completely satisfied. Take the Yamaha M-5000. Very musical amp, uses SK209 all day long.
2SK209 Diff pair ?
Done that before.
https://www.diyaudio.com/community/threads/udness-or-you-dont-need-semisouths.343164/
Patrick
Done that before.
https://www.diyaudio.com/community/threads/udness-or-you-dont-need-semisouths.343164/
Patrick
If your fun in life depends on obsolete JFETs then send me a PM. I will donate my last 2SK170 to you.
And... worked fine ?
What I am wondering about, and this is a serious question. Since many N-chn are symmetrical, meaning drain can work as source and vice versa. Assuming the K209 is, would replacing the P-chn in a complimentary diff pair work if we flip the K209 such that the upper and lower half are source-to-source ??
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That would mean we end up with a quasi-complimentary discrete JFet differential pair with complimentary cascode BJT and MOSFET voltage stage
What I am wondering about, and this is a serious question. Since many N-chn are symmetrical, meaning drain can work as source and vice versa. Assuming the K209 is, would replacing the P-chn in a complimentary diff pair work if we flip the K209 such that the upper and lower half are source-to-source ??
- edit -
That would mean we end up with a quasi-complimentary discrete JFet differential pair with complimentary cascode BJT and MOSFET voltage stage
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You can never make a PJFET from an NJFET.
Semiconductor physics.
Of course a 2SK209 diff pair works fine.
Many examples built.
And better than J113 diff pair in same application.
Oh, and I still have 2000+ 2SK170BL on hand, in addition to V's and GR's.
Plus matching numbers of 2SJ74's, plus many others.
So I shall have more than enough fun for my lifetime.
But most generous of you for your donation, maybe to others.
I am sure there are many takers.
Cheers,
Patrick
Semiconductor physics.
Of course a 2SK209 diff pair works fine.
Many examples built.
And better than J113 diff pair in same application.
Oh, and I still have 2000+ 2SK170BL on hand, in addition to V's and GR's.
Plus matching numbers of 2SJ74's, plus many others.
So I shall have more than enough fun for my lifetime.
But most generous of you for your donation, maybe to others.
I am sure there are many takers.
Cheers,
Patrick
For normal DIY's amp use (not the amp with 1000 JFETs) it is possible to get 2SK/2SJ for the rest of an amp builders' life.
Some quads or octets should do it. Then why not just get them?
It is good practice to get some when you buy other stuff from DIY Store. I have added some many times to the order. I am relative sure I have enough for the future. This will not stop me to get some more if good offers show up 🙂 Inflation proof investment?
Some quads or octets should do it. Then why not just get them?
It is good practice to get some when you buy other stuff from DIY Store. I have added some many times to the order. I am relative sure I have enough for the future. This will not stop me to get some more if good offers show up 🙂 Inflation proof investment?
The plans I have demand more than octet, but I will start with that since that covers my need for a pre- and power amp. One can always get more 🙂
Measure and compare with datasheet,
https://www.diyaudio.com/community/threads/fet-measurements-with-just-a-dmm.308861/
You should download LTSpice (free) to read the .asc files.
Patrick
https://www.diyaudio.com/community/threads/fet-measurements-with-just-a-dmm.308861/
You should download LTSpice (free) to read the .asc files.
Patrick
Never seen K170/J74 with such bended outer legs. And the print (no straight „1“ and no curved „7“) looks like fake.
You can zoom my picture above and compare the print.
But safest is to measure Idss and Vgs. The fakes I had received 2 times before I found a reliable source were with much lower Transconductance, resulting in a much too high Vgs for a given Idss.
K170-BL are usually in the range of 0.5V.
Regards, Jean-Claude
You can zoom my picture above and compare the print.
But safest is to measure Idss and Vgs. The fakes I had received 2 times before I found a reliable source were with much lower Transconductance, resulting in a much too high Vgs for a given Idss.
K170-BL are usually in the range of 0.5V.
Regards, Jean-Claude
I can confirm that Toshiba 2SK170 with 2.5mm pitch legs exists.
They used to be mounted on tapes for automatic insertion.
We know, because we bought a 3k-reel from local Toshiba distributor.
That is not to say whether those posted above is genuine or not.
You need to test, at least Idss and Vgs, preferrably also Yfs.
https://pearl-hifi.com/06_Lit_Archive/14_Books_Tech_Papers/Borbely_Erno/JFETS_The_New_Frontier.pdf
Fig. 5
Patrick
They used to be mounted on tapes for automatic insertion.
We know, because we bought a 3k-reel from local Toshiba distributor.
That is not to say whether those posted above is genuine or not.
You need to test, at least Idss and Vgs, preferrably also Yfs.
https://pearl-hifi.com/06_Lit_Archive/14_Books_Tech_Papers/Borbely_Erno/JFETS_The_New_Frontier.pdf
Fig. 5
Patrick
The most surprising thing is that the LSK170 drops more than the LSJ74.
i.e. Drain current Id depends more on Vds, or less ideal "penthode" characteristics.
My own conclusion :
Only use Toshiba, especially as N-P pairs.
Patrick
i.e. Drain current Id depends more on Vds, or less ideal "penthode" characteristics.
My own conclusion :
Only use Toshiba, especially as N-P pairs.
Patrick
Or use circuit designs which are insensitive to channel length modulation (spice parameter LAMBDA). If d(Ids)/d(Vds) is a problem, arrange to operate the JFET at constant Vds; solved. Here's one possibility among many.
