Easy Way To Spot Genuine K170 & J74 Transistor

As we know that finding the original 2SK170 & 2SJ74 is very hard now. Some seller might sell them in pairs for about US$50. I remember 8 years ago I bought this transistor only US$2 each. No wonder the price jump that higher due to the Toshiba itself who made this J-FET is already stop production for few decades ago. As long you get the genuine then it is good. But you might consider not getting the fake one for sure. Especially if you don't know how to check it visually, then I tell you the clue for it.

You cannot check the performance of idss this transistor before you buy. Then this is a good example for spotting the genuine K170. First thing you cannot notice only by the marking. The very left transistor is J74 but the wording is washed away due to improper storage for long period of time. Both of them are genuine by the way.

Then you should notice that the wording for K170 has bigger font than the wording bellow it. The 'BL21' wording should be smaller. All genuine K170 & J74 has this common characteristic and this is the only way to spot the genuine and the fake.

So you can search many seller sell this transistor for cheap, then you should remember the font of the wording that never fail to telling it. The fake one has the same size of font between upper and lower wording.

Let's take a look the parcel from Spencer that I bought few years ago.

I did import this J74 because there is no seller in my country selling it with reasonable price.

Then you see the wording, it is genuine!

The most nightmare for DIY'ers is working on the project with the fake components. So beware of it rather the project could not go as per expected.

Disclaimer: Any statement and photos in this article are not allowed to copy or publish without written permission from the writer. Any injury or loss from following tips in this article is not under writer responsibility.