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Replacement For Toshiba 2SK170/2SJ74
Replacement For Toshiba 2SK170/2SJ74
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Old 16th September 2019, 05:49 PM   #401
Leicaphile27 is offline Leicaphile27  Canada
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This is my first post. Hope this isn't a dumb question. Can you use K170 / J74 in BL grade which have not been matched? (I'm building an F5) What are the risks/consequences of proceeding in this way. Will an amp built with matched devices sound better?
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Old 16th September 2019, 06:58 PM   #402
Zen Mod is offline Zen Mod  Serbia
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Replacement For Toshiba 2SK170/2SJ74
how far unmatched?
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Old 16th September 2019, 07:33 PM   #403
Leicaphile27 is offline Leicaphile27  Canada
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The both devices are BL grade, but the IDSS is unknown.
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Old 18th September 2019, 02:07 AM   #404
woofertester is online now woofertester  United States
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Quote:
Originally Posted by Leicaphile27 View Post
The both devices are BL grade, but the IDSS is unknown.
It is relatively simple and straightforward to measure Idss and gain. If you are going to DIY build an amplifier, you should be able to measure your JFETs. If you need help, there are plenty of people here who will help.
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Old 18th September 2019, 03:16 AM   #405
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Replacement For Toshiba 2SK170/2SJ74
use this

9V battery instead of 12V as marked, will do the job


inform here what you got
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File Type: gif JFETMatching.gif (2.6 KB, 341 views)
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Old 18th September 2019, 04:49 AM   #406
ThermalAlchemy is offline ThermalAlchemy  United States
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today on youtube (XrayTonyB) talked @7min about on DIYaudio matching transistors. There is a circuit board to build for matching?

I just bought 150 Vishay IRFP240PBF for $154 at IRFP240PBF in Tube by Vishay | Mosfets | Future Electronics

on Findchips website i found LSK170B at LSK170B-TO-92 Stock and Price by Distributor

Im ready to buy 100 of each and learn how to match and buy or make what ever I need.

If any one can guide us to the thread here at DIY for matching.the DYI search engines is sometimes like using Goggle translate Chinese to english to find things.
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Old 18th September 2019, 10:20 AM   #407
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Replacement For Toshiba 2SK170/2SJ74
FW site - articles - mosfet matching

if you need more info , regarding actual conditions to accommodate for actual project , ask here

but not in this thread
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Old 18th September 2019, 05:08 PM   #408
Gyuri is offline Gyuri  Hungary
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If I'm right, measurement above, suggested by my friend, reveals only one parameter, IDSS.
I had to pay for my lessons, I have bought some JFETs, measured IDSS, found to be O.K., then turned out fakes:
(JFET represented by green line is genuine one, red one is clearly fake.)
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File Type: jpg 2SJ74BL_Genuine_and_Fake.jpg (510.5 KB, 247 views)
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Old 18th September 2019, 06:26 PM   #409
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I forgot to mention, if it wouldn't be clear, these two has the same IDSS, about 10.4 mA.
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Old 18th September 2019, 09:44 PM   #410
Leicaphile27 is offline Leicaphile27  Canada
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I'd like to thank everyone for their helpful replies. Especially on how to measure IDSS. The Jfets I purchased from Spencer in Singapore haven't arrived yet. Measuring them should be straightforward. My question, however, is more along the lines of how much variance between the N and P channel is okay? Also, spec variance for BL grade range from 6-12...what it optimal and what happens the further you from optimal. Does it increase noise? Does sound quality deteriorate?
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