My Transistors, original or copy? - Page 46 - diyAudio
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Old 16th February 2012, 07:28 PM   #451
pdul is offline pdul  Denmark
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maybe if we bought more fakes, they would start faking the fakes, using originals
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Old 17th February 2012, 12:34 PM   #452
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Im intigued as to what my Fake 2SK170BL actually are.

At a pure guess they are 2SK170GR - what is the best way to measure these devices for passive parameters ?

I've got a MM that can measure capacitance. I don't want to go to too much bother in testing them, but if they are 2SK170s I might still be able to use them.

Last edited by KatieandDad; 17th February 2012 at 12:42 PM.
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Old 17th February 2012, 12:38 PM   #453
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Quote:
Originally Posted by KatieandDad View Post
measure these devices for passive parameters ?
Idss and gm should be enough.
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Old 17th February 2012, 12:42 PM   #454
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Can you suggest a simple circuit to measure gm. Idss has already been established to lie within the normal range of the GR version.
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Old 17th February 2012, 01:46 PM   #455
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Say transconductance is 20mS, is 20mA for 1000mV, aka 50mV per mA.

Simple 5Vdc power supply (LM7905), and a voltage divider (trimpot + resistor) on the JFET gate.
(plus a resistor on the JFET drain to measure the current)
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Old 19th February 2012, 01:34 PM   #456
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Quote:
Originally Posted by jacco vermeulen View Post
Say transconductance is 20mS, is 20mA for 1000mV, aka 50mV per mA.

Simple 5Vdc power supply (LM7905), and a voltage divider (trimpot + resistor) on the JFET gate.
(plus a resistor on the JFET drain to measure the current)
?????????????????????????????????????????????????? ?????????????

Could you provide a simple drawing for us oldies.
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Old 19th February 2012, 01:45 PM   #457
spind is offline spind  Canada
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Should be a piece of cake for someone with '30 years of experience' !!
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Old 19th February 2012, 01:57 PM   #458
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I'm OK with transisitors but I'm not familiar with FETs. I wouldn't have asked the question if I knew the answer.
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Old 20th February 2012, 04:04 PM   #459
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Quote:
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Should be a piece of cake for someone with '30 years of experience' !!
There are too many people here who like to say "I am clever and I could do it." Could some of them try providing a few answers.
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Old 21st February 2012, 04:19 AM   #460
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http://www.tkhifi.com/div/Erno_Borbe..._articel_1.pdf
there's a tester shown, but it shows "conceptual" current sources, so you'll need to "roll your own"

theres also a previous thread on diyaudio Accurate measurement of jfet gm
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