are these fakes

[samoloko]

bought sj74GR, k117GR, SA970GR, SC2240GR
what do you think are they fakes

 

[HumbleDeer]

They look whanky to me.

The build quality, the quality of the lettering.. it doesn't please me.

- Anna

 

[6L6]

Only looking at the photos provided, the K117 looks perhaps genuine, the J74 looks fake. The text looks wrong on the J74, good on the K117. I could be wrong. But I've never seen plastic flashing on the metal legs of a Toshiba.

Measure Idss of the J74, what do you get?

 

[kamis]

Only 2SK117 are genuine. Look at wider center line at the top of case, all genuine Toshibas have it. I have never seen genuine Toshiba without it. Testing J-fet is easy and reliable, but testing BJT is impossible in a simple way.

 

[samoloko]

thank you guys
did you see sa970 and 2240 with text TC
all transistors look smaller to me
k117 measures correct for Idss and also one of transistors, other says nothing when try to check hfe
one j74 Idss was 5.9, other - 6.2

 

[Soundhappy]

one j74 Idss was 5.9, other - 6.2

Your 2SJ74 look not like my jfet.
I recognise number 7 with typical Toshiba curve and plastic case details are not the same.
Best regards

 

[juma]

Judging by pictures is unreluable. Toshiba had production batches that differ visually.
Good way to check them vould be:
- Measure Idss and note it for every JFET
- Measure Id and Vgs of every JFET with 10R source degenereation and note it
- Compare the measured data with transfer curve given in datasheet

 

[MASantos]

Another visual cue for genuine devices is the slight oxidation of the metal where the legs enter the plastic casing.

 

[kamis]

I have seen countless genuine Toshibas , both J-Fets and BJT from any vintage and all have the same case and leads shape and dimensions, and all have wide center line at the top, there is no exception.
My local electronic parts store sells fake 2sk170BL similar to first picture.I bought five pieces, measured Idss and vp according to Erno Borbely jig schematic, and they are probably repacked J112 or similar. Vp is three times higher than genuine samples. I returned them and got money back, and gave them an advice not to sell fake transistors. They told me that they had received them as genuine Toshiba from Holland distributor.It is much more difficult with ultra low noise Japanese BJT on E-Bay. Do not waste your money.

 

[kamis]

Another visual cue for genuine devices is the slight oxidation of the metal where the legs enter the plastic casing.

Yes, you are right.