Where to buy genuine Toshiba 2SK170 BL?

[stason99]

Can someone recommend a trusted ebay seller or another source? I need only 2-6 of these transistors.

Thanks!

 

[Dan Kennedy]

Send me an address, I'll throw some in the mail.

 

[Bo Deadly]

I actually bought a bunch from different sellers and compared them to see if there was a difference:

  https://groupdiy.com/index.php?topic=66423.0

The conclusion was that there was in fact a significant difference that fell into two distinct gain / noise categories. So I assume the higher gain ones were legit and the others were not. So my guess was that sellers alweit and ceitron were legit but hkutsource and giorgio11185 are not. You should assume that all 2sk170 on Ebay from Asia sellers are fakes. Or sellers that are clearly Asia sourced but have a store in the US or wherever you are are also probably fake. Look at there other items for sale. If it's all sorts of unrelated trinkets, probably fakes.

However, it is worth mentioning that the fakes could perform very well although there was enough variation that they would need to be selected if I wanted to actually use them for something. I had one of the fakes in a microphone and it sounded great. I swapped it out for one that I concluded was authenticate and could not measure a difference (although measuring microphones is rather difficult).

 

[elskardio]

I bought my last batch from Banzai. They look pretty genuine to me 

https://www.banzaimusic.com/2SK170BL.html

 

[stason99]

Send me an address, I'll throw some in the mail.

I sent you a PM.

Thank you all!! Very helpful information!

 

[rackmonkey]

Some more Idss/Vgs curves of 2SK/LSK 170 and 370 (BL and GR) from several sources. Genuine 2SK-170-BLs I bought from Mouser can be seen in the purple/green grouping to the right of the circled "batch 2" group (there are a couple of other originals in there from Mouser as well, but bunched in with a lot of others). There's a group of LSK-170s to the right of that (sort of hard to find in the crowd in this shot). Labelled batches 1 and 2 were a comparison of two different lots of BLs from Banzai. Both were within Vgs(Off) range from the Toshiba datasheet, but as with many sources these days, the admittance (characterized by the slope of the curve) is lower than the known-originals. The lack of consistency in grouping the batch 1 group vs all others also gives me some pause, but isn't a dealbreaker (as just about everyone here knows, JFET variability range within the same process is more than double that of BJTs; but original Toshibas and Linear Systems FETs measure quite consistently). They'll all more or less work in similar applications, but if I'm trying to ensure I'm getting the all around performance (and the relative consistency) of the originals, I'd use the LSK-170 (A grade) from Linear. The only challenge with those is that they go quickly at Trendsetter when they have them in stock.

After going crosseyed staring at JFET traces of over 25 types (most bought from Mouser well before through hole JFETs started going extinct or inherited from a couple of retired TI engineers), I suspect that more than a few PF5102s (still pretty widely available) are being relabeled as 170 and J201. The fake 201 buyers are really getting burned on that deal. 

 

[Bo Deadly]

Nice work rackmonkey. This is exactly what I found in my limited study. There are two distinct and very consistent gain groupings with the real 2sk170's being quite a bit higher.

 

[rackmonkey]

Nice work rackmonkey. This is exactly what I found in my limited study. There are two distinct and very consistent gain groupings with the real 2sk170's being quite a bit higher.

Did you see batches of genuine lots with Vgs(off) outliers like the 1st Banzai grouping in any of your tests as well? Given that it lies within the data sheet spec (right at the edge, at -1.5V), i didn’t flag it as obviously suspect, but it’s interesting that it’s not only got a different admittance characteristic than the known genuine batches, but also one of only a couple batches I’ve seen that didn’t test right amidst the main group like all others.

 

[Bo Deadly]

I didn't measure Vgs(off) but I think it is expected to vary quite a bit whereas the gain / admittance characteristic is very consistent for the genuine parts. Although your analysis is better than mine because you used Mouser parts as the control group, I think my results are good enough to claim that our results independently verify each other. So the Banzai parts do not exhibit the gain / admittance characteristic consistent with authentic 2SK170.

But again, it is worth noting that the fakes are actually pretty good. In a way they're actually too "good". IIRC I found that the noise floor of the fakes was technically lower (but with less gain the net effect is 2SK170 makes for better SNR). Also, in the common emitter type of circuit I used in my test, the second harmonic was 7-8dB higher at ~40dB down from the fundamental with authenticate 2SK170. If pushed, that difference might be audible. Meaning the fakes have less distortion. So if you want a cleaner circuit, use a fake. If you want higher gain with a dash more 2nd, use authentic 2SK170.

 

[Whoops]

Can someone recommend a trusted ebay seller or another source? I need only 2-6 of these transistors.

Thanks!

I don't buy transistors on Ebay since I had bad experiences in the past, there's to many fake/re-stamped transistors.

2SK170BL I buy from Banzai in Germany for 1€, never had problems with those:

https://www.banzaimusic.com/2SK170BL.html

you have also 2SK170GR, its pricier:

https://www.banzaimusic.com/2SK170GR.html

 

[mutterd]

what about the new Linear Systems ones?

http://www.linearsystems.com/product-search-result.html?type=products&partnumber=LSK170&match=true

 

[analogguru]

.... the fakes are actually pretty good. .... the noise floor of the fakes was technically lower .... the fakes have less distortion. .....

So are the alleged "fakes" Field Effect Transistors ?
Do the alleged "fakes" wear a Toshiba symbol ?
And do the alleged "fakes" fulfill the specifications of a 2SK170 ?
If they are FET's, don't wear a Toshiba symbol and fulfill the required 2SK170 specs (or even better) than they are NO FAKES, they are so called "second source".

I am really tired of this never ending claim "fake, fake, fake.... (fake your booty)" which itself is most of the time a fake (news).

A µA741, a µA723 were first produced by Fairchild, a NE555 was first produced by Signetics and no one cries "fake, fake, fake....." when another company produces a µA741, LM741 (you name it), a µA723, LM723 (you name it too) a NE555, LM555 or a 2N3055.

 

[Bo Deadly]

If they are FET's, don't wear a Toshiba symbol and fulfill the required 2SK170 specs (or even better) than they are NO FAKES, they are so called "second source".

If they're sold as "2SK170", that is a designation for a part with specific characteristics. The gain and noise differences are too significant to call those Bonzai and Ebay parts legitimate 2SK170. They are clearly another part entirely stamped with "K170" to look like 2SK170. If the parts were advertised as 2SK170 from a reputable manufacturer that had a website and a datasheet, then we could test those and debate their value as a second source. But non-branded transistors from Ebay seller yuwewe12345 do not qualify as second source.

 

[stason99]

what about the new Linear Systems ones?

http://www.linearsystems.com/product-search-result.html?type=products&partnumber=LSK170&match=true

I'd also like to know that.

 

[rackmonkey]

I'd also like to know that.

If you look back at my first response, you’ll see that these were tested. They are not “new”. Linear Systems has been filling the need for legitimate through hole JFETs for many years now. In fact, if one has a need for a through hole JFET with specific performance characteristics these days, LS is often the only choice. They perform identically to the legacy parts. Their noise screening processes are excellent for parts like the 170 or 389. It’s really the only 100% reliable source for those now.

Trendsetter Electronics carries them. There may be other distributors.

 

[analogguru]

If they're sold as "2SK170", that is a designation for a part with specific characteristics.

Exactly, and this are the MINIMUM requirements.

The gain and noise differences are too significant to call those Bonzai and Ebay parts legitimate 2SK170.

You didn't answer my question:
"And do the alleged "fakes" fulfill the specifications (= minimum requirements) of a 2SK170 ?"

They are clearly another part entirely stamped with "K170" to look like 2SK170. If the parts were advertised as 2SK170 from a reputable manufacturer that had a website and a datasheet, then we could test those and debate their value as a second source. But non-branded transistors from Ebay seller yuwewe12345 do not qualify as second source.

Here you are totally wrong, in reality it is like this:
"In the early days of thermionic valve (vacuum tube) manufacture, each manufacturer gave a number to the types they manufactured. In this way there were vast numbers of different numbers for devices many of which were virtually identical. It soon became obvious that a more structured approach was required, so that the same device could be bought regardless of the manufacturer.

The same is true for semiconductor devices, and manufacturer independent numbering schemes are used for diodes, bipolar transistors and FETs. In fact there a few semiconductor numbering schemes in use:

    Pro-electron numbering scheme  This diode, bipolar transistor and FET numbering scheme was originated in Europe and is widely used for transistors developed and manufactured here.
    JEDEC numbering scheme  This diode and transistor numbering scheme was originated in the USA and it is widely used for diodes and transistors that originate from North America.
    JIS numbering scheme  This semiconductor device numbering system was developed in Japan and can be seen on diodes, transistors and FETs that are made in Japan.
.....
The aim of the the industry standard numbering schemes is to allow for the identification and description of electronic components and in this case semiconductor devices including diodes, bipolar transistors and field effect transistors, to have common electronic components and component numbering across several manufacturers. To achieve this, manufacturers register a definition for new electronic components with the relevant agency and then receive a new part number.

This approach enables electronic equipment manufacturing companies to have second sources for their components and in this way assure the supply for large scale manufacturing and also to reduce the effects of obsolescence."
"https://www.electronics-notes.com/articles/electronic_components/transistor/transistor-codes-numbering.php"

So let us take a 2N3055. The minimum requirements are clearly defined as 60V, 15A, 115W, hfe: 20-70@4A, fg: 800kHz.

This doesn't mean that the performance can't be better.  E.g. you can take a 2N3442 which superceeds the 2N3055 (140V, 15A, 117W, 800kHz) select them that they have a minimum hfe of 20@4A (specified: 20-70@3A) and write 2N3055 on it and it is a legit 2N3055.

And this is not limited to a specific manufacturer, you can have your own "squarewave" brand.

Nothing else is done by your "reputable manufacturers".  Ever thought about what e.g. "sourced from Process 55" means ?

The manufacturer takes a silicon wafer applies some treatments to it called "Process 55" and gets a bunch of different semiconductors at the end.  Then they are selected and become a 2N5457, 2N5458 a 2N5459 or an other FET - that's it.  There is not produced a special FET (or transistor) type intentionally - the different specifications stem only from selection.

So, if you have a piece wich is in a TO-92 case marked as 2SK170 and which behaves like a FET with the following specifications:

Vgds: 40V
Idss: 2,6 - 20mA
Vgsoff: -0,2 - -1,5V
Yfs: 22mS
Ciss: 30pF
Nf(2): < 2dB

then it is a legitimate 2SK170 regardless of the manufacturer who made it or a branding sign, and not a fake.

And now my initial question again:
"Do the alleged "fakes" fulfill the specifications (= minimum requirements) of a 2SK170 ?"

 

[Bo Deadly]

Exactly, and this are the MINIMUM requirements.
You didn't answer my question:
"And do the alleged "fakes" fulfill the specifications (= minimum requirements) of a 2SK170 ?"

You can't just find a part with the same numbers on a datasheet and then call it that part number. Even Linear Systems does not call their part "2SK170" and those parts have exactly the same gain characteristic as the Toshiba 2SK170. Look at rackmonkey's plot carefully. There are two very consistent and yet very different gain curves with the Toshiba and Linear Systems parts following one curve and the unbranded parts following the other.

Incidentally, the fact that there are two completely different manufacturers (Toshiba and Linear Systems) that make parts with the same exact gain also reinforces my conclusion that the Bonzai and Ebay parts are actually just a different part with K170 printed on them.

The Bonzai and Ebay parts do not exhibit the very specific gain curve of the Toshiba and Linear Systems parts. So for Bonzai and Ebay to advertise those parts as "2SK170" is a deception and therefore I personally consider these parts to be fake. Yes, they are high gain and low noise and generally pretty good parts and "fake" is a strong word and the various parameters are vaguely correct. But those parameters are not "requirements" to be called "2SK170".

And in fact your "minimum requirements" don't match that well. The gain in the 2SK170 datasheet does not list minimum or maximum values. It only has a typical value of 22mS which I measured to be 29mS while the fake parts were only 19mS so presumably my crude measurements were too high (albeit consistent so bad accuracy but good precision) which, if we cross-multiply and divide means the gain of the fake parts is more like only 14mS. Again, the 2SK170 datasheet says 22mS typical. And again, that difference in gain is confirmed by rackmonkey's plots.

There are many parts that are replacement equivalents. But they are not sold under the same part number. If the Bonzai and Ebay parts were advertised as "JSK170" or some other part number with a reference like "good 2SK170 replacement", I would be perfectly fine with that. And I couldn't call them fake because they use a different part number.

 

[analogguru]

You can't just find a part with the same numbers on a datasheet and then call it that part number. Even Linear Systems does not call their part "2SK170" and those parts have exactly the same gain characteristic as the Toshiba 2SK170.

Why do you think Linear Systems calls their parts "L SK170" and not e.g. "LSF578" ?
Simply because they want to demonstrate that they are selling the better 2SK170's.

Incidentally, the fact that there are two completely different manufacturers (Toshiba and Linear Systems) that make parts with the same exact gain....

Did you ever visit the Linear Systems plant where the LSK170 are allegedly produced ?
Maybe Linear Systems gets them "made in japan" in the Toshiba factory ?

.... the various parameters are vaguely correct. But those parameters are not "requirements" to be called "2SK170".....

Obviously you didn't read or understand my explanations concerning when a part can be called a e.g. "2Sxxxx or not.

So again:
"Manufacturers register a definition (= minimum requirements) for new electronic components with the relevant agency and then receive a new part number. (e.g. 2SK170).

This approach enables electronic equipment manufacturing companies to have second sources for their components....."

Now:
"The Japanese Industrial Standards, JIS part numbering scheme for semiconductor devices is standardised under JIS-C-7012.

This scheme uses a type number that comprises of a number followed by two characters and then this is followed by a serial number.

First Number

The first number indicates the number of junctions int he semiconductor device.

    1 = Diode
    2 = Bipolar transistor or single gate field effect transistor
    3 = Dual gate field effect transistor

Letters in positions 2 & 3

    SA = PNP high frequency bipolar transistor
    SB = PNP audio frequency bipolar transistor
    SC = NPN high frequency bipolar transistor
    SD = NPN audio frequency bipolar transistor
    SE = Diodes
    SF = Thyristor (SCR)
    SG = Gunn devices
    SH = UJT (Unijunction transistor)
    SJ = P-channel JFET / MOSFET
    SK = N-channel JFET / MOSFET
    SM = Triac
    SQ = LED
    SR = Rectifier
    SS = Signal diode
    ST = Avalanche diode
    SV = Varactor diode / varicop diode
    SZ = Zener diode / voltage reference diode

Serial number

The serial number follows the first digit and the two semiconductor device type letters. The numbers run between 10 and 9999."   e.g. 170

The original manufacturer defines the new component specs, applies for a part number, receives from the JIS a part number (e.g. 2SK170) and every other manufacturer - even chinese - can produce and sell FET's under this model name as long as they fulfill the laid down JIS-specifications for a 2SK170.  Of course they are not allowed to name them "Toshiba" or use the Toshiba-logo, but the use of the JIS 2SK170 marking is totally legitimate and even intended:

"It soon became obvious that a more structured approach was required, so that the same device (= 2SK170) could be bought regardless of the manufacturer."

 

[shabtek]

thanks for the lesson guru