Thank too for the link to EUVL's paper - I will do some tests to see just what we have here.
-Keith-
Please do those tests. You will learn something and EUVL is a master in transistor matching
That's one I can agree on.
Really bad marking likely is an indication of a fake, but some counterfeiters go to a lot of trouble to match the markings as closely as they can. Look a few pages back in this thread at the LT1084 stuff I posted for an example.
Variations of how the marking looks varies from batch to batch with genuine items, sometimes quite a lot. Some manufacturers, like Linear Technology, try to get a consistent marking, others like Analog Devices show much more variation.
The white printing may only indicate on old batch and the laser etched a new(er) batch.
In the end, the measurements will reveal if they are fake.
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Hi Nic,
Didn't know it was you who sold these. Otherwise I would have been more careful making this statement. I'm even buying matched 2Sk2013/2SJ313 from you for years. So you are certainly a trusted seller!
In past years I have bought more than 20+ small batches of JFET's from different vendors, webshops, Ebay and Aliexpress in search for real ones, and all my JFET's with different markings were quickly discovered to be fakes. The Idss most of the time around 12-18mA for a BL. The Idss getting lower, instead of slowly getting higher, when you first put them in your test jig. And always lower Yfs, around 5 - 10 mS.
So from my experience different markings = fake. But I can be wrong!
I was planning to order some new 2Sk2013/2SJ313 with you, maybe you can send an extra J74 or K170 and then I'm happy to measure it by hand and post a curve here.
Best, Walter
Another photo of obsolete Toshiba fets with different style markings (the leads are already cropped and bent).
These are in my little spare parts collection at work for a specific product. Still a couple of hundred in stock from a last time buy. They look like the top ones with white markings.
The supplier is (or rather: was) Arrow Electronics, so no doubt these are genuine (not sure about who supplied the bottom one, though).
The bottom one with laser markings looks a bit odd, but they were used without complaints from the customer. I also find the three dots kind of peculiar.
These are in my little spare parts collection at work for a specific product. Still a couple of hundred in stock from a last time buy. They look like the top ones with white markings.
The supplier is (or rather: was) Arrow Electronics, so no doubt these are genuine (not sure about who supplied the bottom one, though).
The bottom one with laser markings looks a bit odd, but they were used without complaints from the customer. I also find the three dots kind of peculiar.
Weird 2SK170
Hi all,
We all know that eBay if full of fake J74/K170.
Anyhow I went and bought some from Germany. 20pcs for like 15€ to be exact.
I must say I have not seen this kind of K170BL before.
Thickness: ~3.65mm
IDSS: 14-19mA (on the 4 I measured so far)
Yfs: 30-35mS (tested 2pcs, 200mV change in VGS gives 6/7 mA change in IDS 6mA/0.2V = 30mS, right?)
Laser marking looks like top quality. There are no signs of sanding. No tiled front e.g.
Burr is not Toshibalike. (long and centered) It is short and towards the side, but also pretty much all around the device and thus hard to distinguish from photo.
If you look at the leftmost 2 you should see the burr on top of the devices.
I have received fake toshiba JFETs multiple times, but Yfs has always been way below the Toshiba specified 22mS typ.
What could these be???
Not many JFETs have that high Yfs.
I wanted to ask the experts before I make a claim
Hi all,
We all know that eBay if full of fake J74/K170.
Anyhow I went and bought some from Germany. 20pcs for like 15€ to be exact.
I must say I have not seen this kind of K170BL before.
Thickness: ~3.65mm
IDSS: 14-19mA (on the 4 I measured so far)
Yfs: 30-35mS (tested 2pcs, 200mV change in VGS gives 6/7 mA change in IDS 6mA/0.2V = 30mS, right?)
Laser marking looks like top quality. There are no signs of sanding. No tiled front e.g.
Burr is not Toshibalike. (long and centered) It is short and towards the side, but also pretty much all around the device and thus hard to distinguish from photo.
If you look at the leftmost 2 you should see the burr on top of the devices.
I have received fake toshiba JFETs multiple times, but Yfs has always been way below the Toshiba specified 22mS typ.
What could these be???
Not many JFETs have that high Yfs.
I wanted to ask the experts before I make a claim
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Sorry I sort of missed that WalterW's recent post was about JFETs.
I browsed through the thread too quickly
But there is the difference that WalterW measured (like I in every other case did) too low Yfs.
And yes, IDSS has a tendency to drop like 1 mA when these weird devices heat up for me.
I browsed through the thread too quickly
But there is the difference that WalterW measured (like I in every other case did) too low Yfs.
And yes, IDSS has a tendency to drop like 1 mA when these weird devices heat up for me.
I bought the same, 10 pieces in China for around 6 Euros with free shipping :
They measure all around 15,5 - 16,5 mA Idss, 2 are 14.5.
When I change the Vgs 100mV they lower from 15.50 to 12.35mA.
So around 32mS!
I was surprised for that high Yfs indeed.
Also the 1 in 170 is like this: 1 and not like this: l .
So good looking fakes, BL is never 15-16mA.
They measure all around 15,5 - 16,5 mA Idss, 2 are 14.5.
When I change the Vgs 100mV they lower from 15.50 to 12.35mA.
So around 32mS!
I was surprised for that high Yfs indeed.
Also the 1 in 170 is like this: 1 and not like this: l .
So good looking fakes, BL is never 15-16mA.
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I had a local shop in Vancouver BC I purchased parts from on a regular basis for my repair shop. One day I got back to the shop to find a transistor in a metal TO3. The transistor number was only ever made for TO220.
I got suspicious when one day they told me they could get MJ15024/25 out of a vendor in Germany cheaper than buying them USA including freight.
These guys were not dishonest but they were in denial. They just wouldn't believe one of there vendors would sell them fake parts. I heard from them a few years later they threw a guy out of their shop for accusing them of selling fake parts.
Some vendors just stick their heads in the sand when it comes to fake parts. Who has time to test and verify ever single transistor that comes through the door.
It's a very sensitive issue for vendors. I think it might be best to simply tell them the part doesn't meet spec and let them deal with it or communicate it in some other non accusing way.
I got suspicious when one day they told me they could get MJ15024/25 out of a vendor in Germany cheaper than buying them USA including freight.
These guys were not dishonest but they were in denial. They just wouldn't believe one of there vendors would sell them fake parts. I heard from them a few years later they threw a guy out of their shop for accusing them of selling fake parts.
Some vendors just stick their heads in the sand when it comes to fake parts. Who has time to test and verify ever single transistor that comes through the door.
It's a very sensitive issue for vendors. I think it might be best to simply tell them the part doesn't meet spec and let them deal with it or communicate it in some other non accusing way.
They do not look bad in the photo, but looking at the sellers prices (fraction of official dealer cost) they are probably fake I'd say.
And yes, many sellers live in denial, like Kessler never understood that their bad looking parts, far outside specs, really could be fake!
What worries me even more is that they kept selling them after I won the case.
On ebay I think feedback is the most powerful tool. Listings will not be removed just because buyers (and experts) claim that item is fake.
And also yes to never accusing seller of selling fakes (except on forums like this). I learned it the hard way. Simply claim them for being not-working. Then you can return them at sellers or PayPal's cost.
Today I received a package from NicMac who sold the strange looking Toshiba's JFET's.
In it was one 2SK170BL and one 2SJ74BL.
I have measured them both and compared them to a matching Idss JFETs from my personal stock.
And sorry NicMac, you are right, they are real Toshiba's!
Tomorrow they are both going back to Italy
The JFET body is exactly the same size, pins are the same, the stripe at the top is in the middle. They look good. When I place them in my test jig Idss rises also, which is good.
Have a look at the numbers, I measured the Id - Vgs in 50mV steps.
The Toshibas are cut-off at around 500mV that is according to the datasheet. See picture what I measured.
Look at the fake it is cut-off at 750mV! and Idss is above spec.
In it was one 2SK170BL and one 2SJ74BL.
I have measured them both and compared them to a matching Idss JFETs from my personal stock.
And sorry NicMac, you are right, they are real Toshiba's!
Tomorrow they are both going back to Italy
The JFET body is exactly the same size, pins are the same, the stripe at the top is in the middle. They look good. When I place them in my test jig Idss rises also, which is good.
Have a look at the numbers, I measured the Id - Vgs in 50mV steps.
The Toshibas are cut-off at around 500mV that is according to the datasheet. See picture what I measured.
Look at the fake it is cut-off at 750mV! and Idss is above spec.
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I think their 2SK364 were genuine and 2SK363 were fake. Also watch out for their "Japan Transistor" items which are ISC
I think their 2SK364 were genuine and 2SK363 were fake. Also watch out for their "Japan Transistor" items which are ISC
What is ISC?