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Old 12th September 2008, 02:02 PM   #1
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Default Are these fake 2SK389?

I hope this is the correct forum to post........so are these fakes? besides physical appearance , anyway to verify their authenicity?

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Old 12th September 2008, 03:55 PM   #2
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Hmmmmm...no one? i remember there was this group buy here and quite a number of members here received the transistors and were able to tell they were fakes from their outlook...
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Old 12th September 2008, 04:02 PM   #3
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I would say those are fakes (sorry!)...they should not have rounded legs like in your image.
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Old 12th September 2008, 04:03 PM   #4
Magura is offline Magura  Denmark
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Or the easy solution.....test them


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Old 12th September 2008, 04:19 PM   #5
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Quote:
Originally posted by aparatusonitus
I would say those are fakes (sorry!)...they should not have rounded legs like in your image.
the legs are not rounded, the angle of the pics make them percieved as rounded. they are actually flat rectangular cross-section. appreciate your opinion.
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Old 12th September 2008, 04:20 PM   #6
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Quote:
Originally posted by Magura
Or the easy solution.....test them


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Magura, can u advise on ways to test them? i would love it to be as simple as possible...
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Old 12th September 2008, 04:22 PM   #7
Magura is offline Magura  Denmark
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Measure the Ids.

The method can be found for mosfet matching at www.passdiy.com


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Old 12th September 2008, 04:24 PM   #8
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Quote:
Originally posted by Magura
Measure the Ids.

The method can be found for mosfet matching at www.passdiy.com


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thanks! that is useful.
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Old 14th September 2008, 03:18 AM   #9
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it's usually power transistors that get faked. these look like maybe multiple jfets or jfet dual diff amps. actually checking the datasheet, they're dual jfets on a single substrate, for diff amps, etc...

i doubt they're fakes. you could measure Idss, but the datasheet says the Idss can be anywhere from 2.5 to 20 ma.

a better way would be to measure the differential Vgs. you apply 10 volts across the D-S on both transistors and meaure between the gates. the difference between the two gates should be 20mV or less.

that will be a more difficult characteristic to fake with two dicrete fets in the same package.
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Old 14th September 2008, 04:53 AM   #10
xaudiox is offline xaudiox  Philippines
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I bought the same Jfets from ebay (audiotek168 seller).. i received them last friday.

I havent tested them yet but their physical appeance tells me that they look geniune i think.. I've seen photos of the fakes 389 in the last groupbuy.

the pins of this jefts are very different from the groupbuy..they dont have solder and all pins are square not rounded..
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