Non-EU mini BG for FQA19N20C and FQA12P20 - Page 2 - diyAudio
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Old 28th April 2008, 07:51 PM   #11
DaveM is offline DaveM  United States
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I'd be in for 20 of each
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Old 28th April 2008, 09:24 PM   #12
Luke is offline Luke  New Zealand
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I take it these wont be matched?
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Old 28th April 2008, 10:22 PM   #13
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Replacements for IRFP240 and 9240 is that right?

Count me in for 60 pieces N-channel and 36 pieces P-channel, or something in that neighbourhood

Is the standard package for these 25 in a rail as well? If so, I'll go for something like 75 and 50 or whatever's convenient for you.

Thanks for arranging this Dennis
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Old 29th April 2008, 02:39 AM   #14
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Quote:
Originally posted by sandstorm33
Mouser has FQA19N20 250 pcs 0.57 ea and FQA12P20 250 pcs 0.69 ea
I was looking into this until I realized the brokerage fees
would wipe out any saving...

Dennis
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Old 29th April 2008, 03:08 AM   #15
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Quote:
Originally posted by Luke
I take it these wont be matched?
Well, I've been thinking about this. It's
certainly a lot of work, though it may be
worth it.

My understanding is that the
EU GB will Vgs match the parts in pairs.
Naturally there will be some parts that
don't match well and will be rejected. I
think Patrick has budgeted 10% as
duds.

Any opinions on whether we should try
matching the parts?

Cheers,
Dennis
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Old 29th April 2008, 06:32 AM   #16
EUVL is offline EUVL  Europe
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Dennis,

According to the datasheet, the P and the N parts have different nominal Vgs at 1.3 or 2A (the P part about 1V higher). So any attempt to match P to N fet will probably end up with a hugh reject rate.

I only promised to match amongst Ps and amongst Ns. That way, you can at least build identical stereo channels. With a bit of luck, you can build very nicely matched balanced version for even harmonics cancellation. That is the attraction of doing balanced.

Of course there are tricks to get better distortion cancellation in the single ended version, like balancing the open loop gain on the top and bottom half. I speculate that is what Nelson meant by tweaking; so I am holding my breath.

Thought I mention this for your reference.

And don't underestimate how much time you need to match 900 FETs. Will take you one working day easily. And you then need to sort, repack, .......


Patrick
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Old 29th April 2008, 10:02 AM   #17
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Hi Patrick,

Thank you for your comments. Yes, I was thinking of
Vgs matching only the N's with N's and P's with P's
and didn't make it clear. Thanks for pointing it out
explicitly.

Matching will definitely be a major chore. I matched
a batch of 125 mosfets a few years ago and it
took me ~4 hours. I'll be lucky to get a single
polarity matched in one day.

Hmmm....maybe I shouldn't be so quick to agree to
anything.

Cheers,
Dennis
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Old 29th April 2008, 10:39 AM   #18
EUVL is offline EUVL  Europe
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I guess you can order from Mouser (we can't easily), so why not just restrict the GB to 250 pairs ?

Half your matching work load.



Patrick
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Old 29th April 2008, 11:00 AM   #19
Luke is offline Luke  New Zealand
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Hi Dennis,

I would like 100 N channel and 50 P channel please. It would be nice if they came in rails as they usually match nicely:-)

Thanks Arthur
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Old 29th April 2008, 12:13 PM   #20
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Hi Dennis,

I would not ask you for matching if I can get whole rails. I am happy enough to get these so much cheaper than the IR parts cost, and have the fun of matching them myself
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