Are these fake 2SK389?

commstech · 12th September 2008, 01:02 PM

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

commstech · 12th September 2008, 02:55 PM

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...

aparatusonitus · 12th September 2008, 03:02 PM

I would say those are fakes (sorry!)...they should not have rounded legs like in your image.

Magura · 12th September 2008, 03:03 PM

Or the easy solution.....test them

Magura

commstech · 12th September 2008, 03:19 PM

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.

commstech · 12th September 2008, 03:20 PM

Quote:

Originally posted by Magura
Or the easy solution.....test them

Magura

Magura, can u advise on ways to test them? i would love it to be as simple as possible...

Magura · 12th September 2008, 03:22 PM

Measure the Ids.

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

Magura

commstech · 12th September 2008, 03:24 PM

Quote:

Originally posted by Magura
Measure the Ids.

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

Magura

thanks! that is useful.

unclejed613 · 14th September 2008, 02:18 AM

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.

xaudiox · 14th September 2008, 03:53 AM

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..

12th September 2008, 01:02 PM	#1
commstech diyAudio Member Join Date: Oct 2002 Location: SINGAPORE	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?

12th September 2008, 03:02 PM	#3
aparatusonitus diyAudio Member Join Date: Jan 2004 Location: Split, Croatia	I would say those are fakes (sorry!)...they should not have rounded legs like in your image. __________________ Non é mai abbastanza...

12th September 2008, 03:03 PM	#4
Magura diyAudio Member Join Date: Oct 2003 Location: Denmark, Viborg	Or the easy solution.....test them Magura __________________ Everything is possible....to do the impossible just takes a little while longer. www.class-a-labs.com

12th September 2008, 03:22 PM	#7
Magura diyAudio Member Join Date: Oct 2003 Location: Denmark, Viborg	Measure the Ids. The method can be found for mosfet matching at www.passdiy.com Magura __________________ Everything is possible....to do the impossible just takes a little while longer. www.class-a-labs.com

14th September 2008, 02:18 AM	#9
unclejed613 diyAudio Member Join Date: Dec 2006	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. __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/


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12th September 2008, 02:55 PM	#2
commstech diyAudio Member Join Date: Oct 2002 Location: SINGAPORE	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...

14th September 2008, 03:53 AM	#10
xaudiox diyAudio Member Join Date: Jul 2006	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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