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more complementary pairs than IRFP240/IRFP9240
more complementary pairs than IRFP240/IRFP9240
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Old 12th February 2018, 02:56 PM   #1
marconi118 is offline marconi118  Germany
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Default more complementary pairs than IRFP240/IRFP9240

it seems that the IRFP240/IRFP9240 is not the best complementary pair

some state that IRFP240 match better with IRFP9140

or

244/9240
340/9240

the same for irf630/irf9630 a better match is irf630/irf9530

having to buy new parts what pairs match the best?
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Old 12th February 2018, 04:31 PM   #2
Bensen is offline Bensen  Belgium
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Have a look here, should/might be interesting for you.

Low power mosfet's - complementary pairs
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Old 12th February 2018, 04:57 PM   #3
raman15 is offline raman15  United States
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I have used this seller on Ebay......6x Matched IRFP240 N-Ch POWER MOSFET 20A 200V 150W . VISHAY / SILICONIX | eBay

Have had results of Vgs within 0.001 - 0.003V

cheers
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Old 12th February 2018, 05:32 PM   #4
Nelson Pass is offline Nelson Pass  United States
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more complementary pairs than IRFP240/IRFP9240
It's not difficult to get matches if they come from the same tubes.

Also, matching to .1v is generally pretty adequate. At PL we use .01V
only because it's easy to do.

np
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Old 12th February 2018, 05:58 PM   #5
woofertester is offline woofertester  United States
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Quote:
Originally Posted by Nelson Pass View Post
It's not difficult to get matches if they come from the same tubes.

Also, matching to .1v is generally pretty adequate. At PL we use .01V
only because it's easy to do.

np
Do you match pairs for each particular amplifier using that circuit's Vds?

I have looked a the eBay seller Punkydawgs. He uses 9V to characterize his matches. The F4 circuit that I am building uses the K170/J74 JFETs at about 14.4V Vds.

If a pair is matched at 9V Vds, that is no guarantee that they are a match at a higher Vds, correct?
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Old 12th February 2018, 06:10 PM   #6
Zen Mod is offline Zen Mod  Serbia
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more complementary pairs than IRFP240/IRFP9240
Papa was talking about mosfets , in post #4

you're asking for JFets

however (regarding your question), matching results are pretty well consistent on slightly higher voltages , too
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Old 12th February 2018, 06:33 PM   #7
pchw is offline pchw  United States
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more complementary pairs than IRFP240/IRFP9240
Quote:
Originally Posted by woofertester View Post
Do you match pairs for each particular amplifier using that circuit's Vds?

I have looked a the eBay seller Punkydawgs. He uses 9V to characterize his matches. The F4 circuit that I am building uses the K170/J74 JFETs at about 14.4V Vds.

If a pair is matched at 9V Vds, that is no guarantee that they are a match at a higher Vds, correct?
The operating temperature inside the closed case will also make a difference. The jfets are very sensitive to the temperature. So, if you want to have a "closely" matched pairs (or quads) under your amp's operating condition, a temperature control jig is also needed.

FWIW, in the F5X project, NicMac acquires hundreds (if not thousands) Toshiba jfets and matched them in NNNNPPPP under Patrick's (EUVL, the F5X designer) matching instructions. There were not too many yields, and each set cost a fortune but still good price for what they are!!! However, they are not perfect match (still good match) in a different operating condition (can be affected by many factors in the DIY world :-)). No prematch set will satisfy each diyer's creativity.

One thing for sure, a matched pair at 9V is going to be many times better than a random pair. Given these jfets (Toshiba and Linear) are close to impossible to buy in bulk to match ourselves, we probably will have to accept the general 9V matching practice to get the project going and be happy.
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Old 12th February 2018, 06:44 PM   #8
finwbu is offline finwbu  Finland
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more complementary pairs than IRFP240/IRFP9240
IRFP150/IRFP9150
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Old 12th February 2018, 07:03 PM   #9
marconi118 is offline marconi118  Germany
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I mean matching the transconductance of the N and the P couple. Not the NN and PP matching
Irfp9140 has closer transconductance to the irfp240 than the irfp140
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Old 12th February 2018, 07:06 PM   #10
marconi118 is offline marconi118  Germany
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Quote:
Originally Posted by Bensen View Post
Have a look here, should/might be interesting for you.

Low power mosfet's - complementary pairs
Exactly what was looking for but for high power mosfet like irfp140 etc
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