Hello All,
I have been looking around for and purchased some 2N5457 and 2N5460 N and P channel JFET’s. I found 2 brands, ON and Central. Both brands are legitimate transistors.
I suppose a third manufacture could also make transistors that also meet the product specifications but not meet the industry requirements for being licensed to manufacture and legitimately label their products as 2N5457 and 2N5460 N and P channel JFET’s. They would be counterfeit or fakes.
Just thinking out loud.
Thanks DT
I have been looking around for and purchased some 2N5457 and 2N5460 N and P channel JFET’s. I found 2 brands, ON and Central. Both brands are legitimate transistors.
I suppose a third manufacture could also make transistors that also meet the product specifications but not meet the industry requirements for being licensed to manufacture and legitimately label their products as 2N5457 and 2N5460 N and P channel JFET’s. They would be counterfeit or fakes.
Just thinking out loud.
Thanks DT
Hi! got 4 matched sets of 4 2SK170BL from eBy seller evrieze some time ago. Should have IDSS within 1mA. I just measured, and the IDSS is from about 13,2-14,4mA, with one at 15,1mA. But all measurements are outside the BL spec, so should I assume that these are fakes? I used a 9V powersupply, positive connected to Drain through a 10 ohm resistor, and connected Gate and Source togheter, and then to negative on powersupply. Measured drop over 10 ohm resistor.
> I used a 9V powersupply
The spec-sheet is taken at 10V D-S, so you should have used a 10.15V supply (to allow for drop in 10r also). But that does not make 12mA into 14mA (and is the wrong way to increase measured Idss).
"Fakes"? Or good 2SK170V (mis-marked)??
JFET are not an exact product. Measure Idss -and- Vgs(off), you know if they will bias-up in your circuit. Use in a high-gain amp, you will know if they hiss (leak).
The spec-sheet is taken at 10V D-S, so you should have used a 10.15V supply (to allow for drop in 10r also). But that does not make 12mA into 14mA (and is the wrong way to increase measured Idss).
"Fakes"? Or good 2SK170V (mis-marked)??
JFET are not an exact product. Measure Idss -and- Vgs(off), you know if they will bias-up in your circuit. Use in a high-gain amp, you will know if they hiss (leak).
The Idss values suggest "V" instead of "BL". The vendor might have done that in order to obtain proper matching. But (s)he should have asked if that would be OK, before shipping. So more measurement is required to know if they're fake 2SK170. Best and most relevant would be noise measurement.
Genuine Tosh jfets have a line - maybe 2mm long - going sideways in the middle of the top. Fakes (strangely!) don't seem to.
And how much did you pay for the matched jfets?
Andy
Dear Cyberkul,
If 2SK170BL IDSS is out of Toshiba datasheet value - it is 100% fake, I measured more than 10000 of 2SK170BL and have never seen even one JFET out of range really the values I saw are in range 6.5-11.5 mA.
If 2SK170BL IDSS is out of Toshiba datasheet value - it is 100% fake, I measured more than 10000 of 2SK170BL and have never seen even one JFET out of range really the values I saw are in range 6.5-11.5 mA.
Yes, I noticed that you wrote that in an earlier post, and I have no reason to doubt your measurements. I’ll borrow a calibrated vmm from work just to make sure my measurements are correct. Also a dual psu in case I want to measure Vp
Here are two pictures through a USB-microscope of one of the transistors. It doesn`t have brownish spots, something with the lighting I think.
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not sure if its absolutely true, but this has circulated around
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Using the test circuit on page one, I expected to read -0,2 to -1,5Volts? So my +0,7V reading indicates a lower gain device?
I sent the picture of the genuine jfet to the seller. He said that anyone could have made it, and that it proves nothing. Anyone know the source of the picture?
He offers a new set of transistors with IDSS in the BL-range. He will not send any pictures of the transistors, and it seems to me that he measures IDSS, nothing else. I could ask eBay to step in and try to get my money back, or I. ould get a new set that is likely fakes as well.
He offers a new set of transistors with IDSS in the BL-range. He will not send any pictures of the transistors, and it seems to me that he measures IDSS, nothing else. I could ask eBay to step in and try to get my money back, or I. ould get a new set that is likely fakes as well.
Typical seller strategy of denial.
I bought some 7.5mm pitch caps from Ali Express.
When they came they were 10mm and wouldn't go in the pcb without bending the leads quite a bit.
I complained and was told that 10mm is in spec for a 7.5mm pitch cap !
+33% out ? I don't think so. Ali express refunded me.
The unique feature of the 2SK170 is the combination of high Idss AND low Vgsoff ie very high Gm
And if I did measure correctly, the VGS (off) is positive, not negative as in the spec sheet.