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Old 25th July 2008, 01:49 AM   #1491
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Quote:
Originally posted by jacco vermeulen
You check the transconductance number of the IRF P-channel before you do.

well - I didn't wrote that you're wrong
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Old 25th July 2008, 01:50 AM   #1492
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B1 raper=>

(me holiday and beach, what's your lame excuse ?)
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Old 25th July 2008, 01:50 AM   #1493
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Quote:
Originally posted by Magura



Go to sleep!


Magura

I can't - I'm chatting right now with some crazy danske
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Old 25th July 2008, 01:54 AM   #1494
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Quote:
Originally posted by jacco vermeulen
B1 raper=>

(me holiday and beach, what's your lame excuse ?)

if you two continue with Off Topic , I'll write to !
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Old 25th July 2008, 05:06 AM   #1495
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> Somebody please remind me again, for use in an F5 topology, what is the reason to choose the IRF or Fairchild MOSFETs over 2SK1530s and 2SJ201s?

>> Transconductance.


According to my measurements, at 1A, IRFP240 has 3.5S, 2SK1530 has 3.2S, so within 10% and IMHO no issue. If you are really fuzzy, then lower the source resistor will compensate for that.

Toshibas are more costly (at least 3x at retail price), and more difficult to get, and not from an American manufacturer.


Patrick
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Old 25th July 2008, 08:46 AM   #1496
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Quote:
Not that it is important, whether at 0.003% or 0.006%
Well at this low THD-level pcb-artwork, wiring, grounding, trafo shielding are already more important and can dominate THD.

But, it's still tempting to use the Toshibas

Nevertheless, the F5's frequency response is very sensitive to parts choice, so if you want to achieve the same results as Nelson shows off in the article one has to stay with the Fairchilds. Otherwise trimming is necessary which not everbody has the equipment for.

Have fun, Hannes
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Old 25th July 2008, 09:58 AM   #1497
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Quote:
Transconductance
Transconductance numbers of the 9240 and SJ201 at 1A-25Vds are more interesting, shame so many matched real Laterals would have to be put in parallel for this one.
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Old 25th July 2008, 10:32 AM   #1498
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> Transconductance numbers of the 9240 and SJ201 at 1A-25Vds are more interesting

Don't trust the datasheets.
In any case, 2SJ201 has more than FQA12P20, but that is not the entire story.

> Nevertheless, the F5's frequency response is very sensitive to parts choice, so if you want to achieve the same results as Nelson shows off in the article one has to stay with the Fairchilds.

I have both versions built, and they have very similar freq response. You just need to read what I already published.

In any case, don't do armchair DIY and start building ...


Patrick
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Old 25th July 2008, 10:49 AM   #1499
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Quote:
In any case, don't do armchair DIY and start building ...
I'm waiting for Nelson's pcbs. Sure I could do my own, but having at least a single Nelson Pass piece is a bit special

I'm still thinking of the Toshibas, it's just that I have more than enough Fairchilds already at hand...

Have fun, Hannes
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Old 25th July 2008, 01:10 PM   #1500
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Another stupid question: Besides the huge price difference, what distinguishes a 2SK1530A from a 2SK1530?
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