Its only possible to detect with curves tracer , oscilloscope ?
Vgs test are sufficient ?
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Mine are en route to the finest test facility around. 🙂 USPS tracking shows that they will arrive there any time now.
I did not get mine from eyelabo, but I don't know if they are from the same supply.
We should have some additional data points soon.
Edit:
http://youtu.be/yoy4_h7Pb3M
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What your 2SK180 batch numbers serial ?
Maybe this give us response.
I have buy from him....Thanks
Greetings
old stuff are dangerous ,why not waiting the brand new SIT from Mr PASS , even at 200$ the pair , a bargain compared to his cousin 300B valve 🙂
And then he posted these on ebay again today! Thank god I red your post first, as I was about to purchase a quad!
Thank you Mike!
As I say, I can't speak for his entire stock, only the pieces I've personally tested, which are still in the post.
I have other stock to test.
He has been helpful and friendly thus far in initiating the return process, and I wouldn't want that mucked up by bad diplomacy.
I have other stock to test.
He has been helpful and friendly thus far in initiating the return process, and I wouldn't want that mucked up by bad diplomacy.
on your photo they are not the same batch serial 
Hi Cwtim01
After your photos all is ok with your 2SK182ES 🙂
but do you have tested your 2SK180 ?
Kindly regards
I only tested 1 piece of 2SK182ES before, but shocked by the news I tested all the 2SK180s I got from eyelabo_jp, attached the results (S/N between 1Z3710-1Z3717). Apparently they seem OK, but would appreciate if someone could confirm.
Need to leave home for work now, I'll test my other 2SK182ES later and report back afterwards.
Attachments
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Thanks for answer Cwtim01
Your Mr. Eyelabo 2SK180 Tokins
all look like good exemplary working sit's
Attachments
I'm not quite as sure, since these curves only go to 30V and the behavior I've been concerned with doesn't really dominate the performance for the first few tens of volts. The few "known good" 180's I have look a good bit more linear in this region than some of these, with the traces nicely parallel having equal drain resistance. I believe I'm seeing the beginnings of what I'll call curl-up and flop-over in some of these curves, where the trace looks like it's peeling up from 0 and flopping over as if a steadily increasing resistance was present at the source. For example, have a look at the 5th image.
Of course the "bad" parts still amplify at the low voltage end (quite a bit in fact) but it was my experience in trying to make them work that the "sweet spot", if I can call it that, is quite narrow since I was relying more on cancellation than inherent linearity.
But, like I said, I can't be certain without more info. All I can suggest is that you try one in-circuit and measure the performance.
If I have time this weekend, I'll try a bad one at low voltage and see how it behaves.
Of course the "bad" parts still amplify at the low voltage end (quite a bit in fact) but it was my experience in trying to make them work that the "sweet spot", if I can call it that, is quite narrow since I was relying more on cancellation than inherent linearity.
But, like I said, I can't be certain without more info. All I can suggest is that you try one in-circuit and measure the performance.
If I have time this weekend, I'll try a bad one at low voltage and see how it behaves.
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Having tested several batches now, I think it's fair to say that his stock is a mixed bag at best, so my cautionary note applies unless and until he is able to do some testing and sorting.
Sadly, despite having had many Tokin SITs in my lab in the last month, I am right back to where I started with just a small handful of good 180's, so I'll continue with the 180 amp for now, then move on to some other things.
Thanks Michael for your comments, I'll stay tuned to your findings. If I can't confirm whether they're good before expiry of the return period (I received them last Friday so 10 days left), I guess I'll return them to eyelabo_jp for refund.
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