Sony vFET Amplifier Part 2

[plasnu]

Voltage gain w/o feedback is determined by the degeneration of the input
pair, and is whatever you want within reason.

With feedback, my prototype was 16 dB gain.

I didn't check it without, but with feedback, the DF is 40. I expect the DF
w/o feedback and the same bias current to be about 70% of the original 18,
about 12 or 13.

😎

Thank you, it sounds very good to me.🙂

It's sad that SIT seems to have no industrial market today, unlike SiC...🙁

 

[2 picoDumbs]

When Tokin still had the production line (apparently destroyed in the quake
and not rebuilt) I had an indirect (not from Tokin) nominal quote of
$250,000 for 2SK77B's. I had a comparable quote from SemiSouth for
more SIT-1 devices and almost made the down payment before they went
under.

The unfortunate fact is that there is not a big enough audience for the parts.
Digital Do Main had the 2SK77B's made originally, and I am under the
impression that its owner did not regard that as a lot of money.

Even with crowd funding, I don't know that you can convince Tokin to
spend the millions it probably would take to rebuild the production line.

I do have a small quantity of the 2SK77B's, and if any of you have some
quantities of the genuine parts, let me know.

😎

I was sought of hoping that $10,000 to $20,000 would cover it. 🙁
I might have a go at trying to make one in the lab for fun. No I dea whether I'll be successful but fun to try.
Are the patents still available online somewhere?

 

[Zen Mod]

beat me if patent alone is enough

if anyone knows , Semisouthfan is guy to ask is there anything in sight , regarding new production of SIC,SIT ......

 

[2 picoDumbs]

I'll chat with other dodos at work to see what is possible.

 

[aspringv]

Happy days on the vfet front! @NP thank you kindly - that's an amazing contribution. I've been reading all these vfet articles with interest over the years with no expectation of being able to get parts for such an amp.

Thanks!

 

[Cambe]

Thank you, Mr. Nelson Pass!
You are definitely 100+ "real" 😎 .

 

[lhquam]

Thank you, Mr. Nelson Pass!
You are definitely 100+ "real" 😎 .

I will second that!

 

[Soundhappy]

I was sought of hoping that $10,000 to $20,000 would cover it. 🙁
I might have a go at trying to make one in the lab for fun. No I dea whether I'll be successful but fun to try.
Are the patents still available online somewhere?

Specialised tech documentations about manufacturing of semiconductor triodes are not for free example : IEEE source
but we have lot information on line

www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA299605

http://libinfo.uark.edu/aas/issues/2003v57/v57a31.pdf

Patent US4889826 - Static induction transistor and manufacturing method of the same - Google Patents

Kick Starter or https://www.rocelec.com/

Kind regards

 

[lhquam]

The semiconductor fabrication process involves much more than the geometry of the device. The geometry of these devices should be no problem, but the doping and other process details could be non-trivial and certainly not something for amateurs.

OTOH, it would be really nice if someone acquired an old fab line and had a knowledgeable old geezer who could make these devices.

 

[2 picoDumbs]

The semiconductor fabrication process involves much more than the geometry of the device. The geometry of these devices should be no problem, but the doping and other process details could be non-trivial and certainly not something for amateurs.

OTOH, it would be really nice if someone acquired an old fab line and had a knowledgeable old geezer who could make these devices.

I'll let ya know what I can get done if at all possible.

 

[2 picoDumbs]

Specialised tech documentations about manufacturing of semiconductor triodes are not for free example : IEEE source
but we have lot information on line

www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA299605

http://libinfo.uark.edu/aas/issues/2003v57/v57a31.pdf

Patent US4889826 - Static induction transistor and manufacturing method of the same - Google Patents

Kick Starter or https://www.rocelec.com/

Kind regards

Thanks for the links.
I'll see what I can get done.
I just need to make sure we have all the necessary equipment. I vaguely remember we made some semiconductors for specialised applications a long time ago.

 

[WalterW]

Where do you work ?

 

[2 picoDumbs]

Research organisation.

 

[Nelson Pass]

The semiconductor fabrication process involves
much more than the geometry of the device. The geometry of these devices
should be no problem, but the doping and other process details could be
non-trivial and certainly not something for amateurs.

If that were not true then Linear Systems would have had exact replacements
for the 2SJ74 long ago.

(As it is, they seem to be getting there.)

😎

 

[Tea-Bag]

And here's the good news.

Presumably those who plan to use matched dual pairs can go with Tea
Bag's boards or they can bolt the extra devices in parallel. The performance
should be about the same either way.
😎

On my end, I have ordered some proto-type boards for these. Hopefully in a month or more time, I will have a working board to offer. Once they are in my hands, if not sooner, I will open up a thread for the board named "AL"

 

[Bones13]

Thanks for the update Tea-Bag.

I need to get on with seeing how well my VFets match, I have 6 sets, and hope to get close on 2 pairs to use for the CSX2, and use the others for the CSX1.

 

[gadut]

i read some member reported that eternal hong store sell relabelled item

m.aliexpress.com/item/1443280472.html?tracelog=storedetail2mobilesitedetail

but any of member here who bought from taobao store?
m.intl.taobao.com/detail/detail.html?spm=a1z5f.7632060.0.0&id=40300679359

i'm still waiting 4pairs of them that was send thru sea shipping, dont know when it will arrive. hopefully they are real, just realise that i only paid ¥200/pair, a lot cheaper that acronman sold for $40/pair

hopefully the letter on taobao picture means "100% original, return if they are fake" 😀

otherwise, i think that i have to refresh diyaudiostore every hour to get papa vfets before it's too late

 

[JRDG]

i read some member reported that eternal hong store sell relabelled item

m.aliexpress.com/item/1443280472.html?tracelog=storedetail2mobilesitedetail

but any of member here who bought from taobao store?
m.intl.taobao.com/detail/detail.html?spm=a1z5f.7632060.0.0&id=40300679359

i'm still waiting 4pairs of them that was send thru sea shipping, dont know when it will arrive. hopefully they are real, just realise that i only paid ¥200/pair, a lot cheaper that acronman sold for $40/pair

hopefully the letter on taobao picture means "100% original, return if they are fake" 😀

otherwise, i think that i have to refresh diyaudiostore every hour to get papa vfets before it's too late

They showed you a real thing but when you got this item maybe different from an item they've shown.

 

[Soundhappy]

Those with only one polarity of VFETs will be addressed in a separate design after that.

😎

Single- ended Sony vfet version with new Mr Pass topology

 

[jps1964]

It is possible to become datasheets (PDF) for 2SJ28 and 2SK82?

Regards,
Jean-Paul