This matches my matching experience as well. Harder to get matches from a batch of P channel types. Maybe I need to order more!!
I found lots of interesting reading from a Croatian VFET expert 'ILIMZN':
http://www.diyaudio.com/forums/pass...-2sk82-e-rank-2sj28-f-rank-5.html#post3822318
Hey, I'm on holiday in Croatia, maybe I can visit him there 😀
http://www.diyaudio.com/forums/pass...-2sk82-e-rank-2sj28-f-rank-5.html#post3822318
Hey, I'm on holiday in Croatia, maybe I can visit him there 😀
Yes who know probably he is drink a coffe in next street bar
just say loudly : VFET !!
that secret Pass word 😀
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Matched LS jfet B grade in Audio Store and about 950 pcs genuine 2SK82 vfets source
i see Diyers have reason to smile
For statistics could you say how much of pairs you find ?
It's a large batch ?
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From 20 pairs (mostly from Acronman, some from other sources), I got 5 matched pairs (within 0.1V) for 2SJ28, a bit more for 2SK82.
Attached the Vgs_Id distribution (@19V Vds) of the 2SK82 (left) and 2SJ28 (right), you can see that the 2SJ28s are spreading across a wider Vgs (only 15 pairs shown here, I have not kept the data for the ones that I sold).
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I think based on the amount of parts I have, the varation is likely identical.
I am doing a second measurement run of the units, they really do need to be mounted on a heatsink, as they draw less current as the unit heats up, given the same bias voltage. so one has to tweak the bias to get it to sit at .500v after a minute or so.
Anyways' I will provide some data based on my results so we can start to discuss real world VFET testing methodology that can be reproduced with some good equipment. I am using a dual +/- Regulated power supply and set at 19v and then bringing the bias down from 30v to whever it wants to stick at .5A I use the multimeters to get more granular than the supply will produce, but they give you a really close idea. Having a heatsink already pre-drilled for TO-3 makes things easier, but labor intensive.
Previously, I was just laying them upside down on a chunk of heatsink with a levered rubber arm ( a Michael R insight) to try to lock the VFET in place. Not good enough.....
If we compare vfets after Sony documentation 33 is the Vp rank
so JA -33 perfectly compatible with others 33 🙂
@ Cwtim01 and Tea-Bag
Super you have vfets for 2 pairs mono push-pull with lower distorsion
let's say " de luxe " version . Congratulations 😀
Quality lab psu and multimeters can only give fiability of mesures
well i need one more psu 🙂
Greetings
so JA -33 perfectly compatible with others 33 🙂
@ Cwtim01 and Tea-Bag
Super you have vfets for 2 pairs mono push-pull with lower distorsion
let's say " de luxe " version . Congratulations 😀
Quality lab psu and multimeters can only give fiability of mesures
well i need one more psu 🙂
Greetings
I tested a couple hundred pairs, for Vgs @ .5A, 20V and got this distribution:
2SK82:
5v 0
6v 6
7v 57
8v 98
9v 55
10v 15
11v 0
2SJ28:
7v 0
8v 24
9v 45
10v 18
11v 69
12v 66
13v 9
2SK82:
5v 0
6v 6
7v 57
8v 98
9v 55
10v 15
11v 0
2SJ28:
7v 0
8v 24
9v 45
10v 18
11v 69
12v 66
13v 9
And with two die/device you only have to buy 1 of each. 😉
BTW, Mototool w/ abrasive cutting disk is the way to go.
Quote from US Patent 5783970 A
From Patent #5783970 A, I found this an interesting comparison between P and N types:
If true, this is disappointing to learn since I only have the P type. Even so, I'm still anxiously awaiting for a kit to become available so I can put them to good use!
From Patent #5783970 A, I found this an interesting comparison between P and N types:
"Interestingly, most modern day power VFET amplifiers that have been devised utilize complementary VFET output devices (P & N) in the power output stage. The one significant short coming of this configuration is the cost and performance penalties of the P type VFET. For example, the P type VFET usually costs about twice that of the N type VFET and delivers only about 70% of the gain, usually with a decrease in speed."
If true, this is disappointing to learn since I only have the P type. Even so, I'm still anxiously awaiting for a kit to become available so I can put them to good use!
I think that article is not about SITs. See post #51 by ilimzn of the thread mentioned below by WalterW (post 327):
http://www.diyaudio.com/forums/pass...-2sk82-e-rank-2sj28-f-rank-5.html#post3822318
So enjoy your 2SJs when the time comes...
http://www.diyaudio.com/forums/pass...-2sk82-e-rank-2sj28-f-rank-5.html#post3822318
So enjoy your 2SJs when the time comes...
Okay, here is a taste of a possible board(s) to work with here. Critism welcome.
I am hoping that Nelson doesn't throw the baby out with the bathwater and re-invent the thing on the next rendition, but if so, I'll move on.
Here is what it will look like kind of mounted. Similiar to Permanders board, with a more modular front end.
edit: added attachment so one can see it bigger and better.
I am hoping that Nelson doesn't throw the baby out with the bathwater and re-invent the thing on the next rendition, but if so, I'll move on.
Here is what it will look like kind of mounted. Similiar to Permanders board, with a more modular front end.
edit: added attachment so one can see it bigger and better.
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this time I had no good luck…… :-(
I bought at Taobao two pairs of SK82/SJ28, 200 Yuan the pair.
https://item.taobao.com/item.htm?spm=a230r.1.14.140.l4ezPb&id=40300679359&ns=1&abbucket=18
look at the four flat curves, these are the new ones,
the four steeper curves are two pairs from Acronman I already had……
The vendor even lifted the price from 200 to 300 Yuan/pair.
😡😡😡
I bought at Taobao two pairs of SK82/SJ28, 200 Yuan the pair.
https://item.taobao.com/item.htm?spm=a230r.1.14.140.l4ezPb&id=40300679359&ns=1&abbucket=18
look at the four flat curves, these are the new ones,
the four steeper curves are two pairs from Acronman I already had……
The vendor even lifted the price from 200 to 300 Yuan/pair.
😡😡😡
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