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Old 12th December 2008, 06:52 AM   #11
steenoe is offline steenoe  Denmark
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Very good, I send you a mail through the forum.

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Old 12th December 2008, 11:03 AM   #12
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I have just done the jfet Idss matching test with 2SK170, using 19VDC of the ac adaptor.

At about 10V Vds, four chosen as flws:

8.50 mA - 8.50 mA
8.78 mA - 8.81 mA


>><<
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Old 12th December 2008, 11:23 AM   #13
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Old 12th December 2008, 12:02 PM   #14
AndrewT is offline AndrewT  Scotland
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Hi Bab,
Wait, don't use those pairs just yet. Add 9 & 11 and 1 & 13 as possible candidates for matched pairs.

Set up an LTP jig and measure the tracking of the prospective pairs. If they are good then keep them for a specialised use that really benefits from matched pairs.

Now, pick two pairs with similar Idss (2% or 3% error is OK) for the B1, it does not need nor benefit from real matched pairs.
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Old 12th December 2008, 12:31 PM   #15
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Quote:
Originally posted by AndrewT

Add 9 & 11 and 1 & 13 as possible candidates for matched pairs.

I feel like a blind . . . How come I couldn't see 9&11 and 1&13?
>><<

It's too late . . . I already chosen the marked four, and returned the others into the unmatched bunch with no marking because I always match them in different ways for the different purposes . . .

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Old 12th December 2008, 11:45 PM   #16
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Babo where did you get all those trannies from?
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Old 13th December 2008, 01:32 AM   #17
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Default Re: Parts

Quote:
Originally posted by enzedone
Babo where did you get all those trannies from?

I got some from Korean manufacturer (upto year 2000).
Some in Norway (year 2000-2002).
Some in China (year 2004-2007).

I like Chinese best. Very good price and quality.

>><<
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Old 13th December 2008, 01:44 AM   #18
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This morning I tried the second round of the matching test.

At about 10.5 Vds, four 2SJ170s having the following Idss finally chosen:

8.50 mA - 8.50 mA
8.67 mA - 8.68 mA

I hope these will well play their role . . .


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Old 13th December 2008, 03:32 PM   #19
moe29 is offline moe29  United States
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I love JHY's posts... this makes me want to build a B1
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Old 13th December 2008, 09:12 PM   #20
steenoe is offline steenoe  Denmark
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Quote:
Originally posted by Babowana
This morning I tried the second round of the matching test.

At about 10.5 Vds, four 2SJ170s having the following Idss finally chosen:

8.50 mA - 8.50 mA
8.67 mA - 8.68 mA

I hope these will well play their role . . .


>><<
Just a suggestion;
You could also use number 2+11 and 9+3. With 2 and 9 as the top J-fet. Check out what was said here:

J-fet matching for B1

That would save you the 2 excact matching sets.

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