Matching large quantities of mosfets

[MJPAudio]

Hi,

Searched the forum for a bit but no luck.
How many fets are roughly needed for to match lets say 4x18pieces irfp240's
Would 100 pieces be enough to find a close enough match?

Thanks
Martin

 

[2 picoDumbs]

What source resistance will be using on the fets?

 

[Soundhappy]

http://www.firstwatt.com/pdf/art_matching.pdf

Classic from Papa you get the advice at the end of article 😀

 

[MJPAudio]

What source resistance will be using on the fets?

0.47ohm

Thanks

 

[2 picoDumbs]

If you buy 4 tubes that are all from the same manufacturing batch you should be fine.
Tell Digikey/Mouser, this is a requirement for the sale.
They will make sure you get what you ask for.

If you are nervous buy 5 tubes, then just sell off what you don't need.

 

[MJPAudio]

24pieces in a tube?

Thanks

 

[2 picoDumbs]

25
Just checked it.

 

[KatieandDad]

Same batch MOS-FETs don't necessarily match perfectly. We needed 4 x 6 hextets and used 100 in the process.

 

[2 picoDumbs]

They don't need to match perfectly if he is using 0.47Ohms source resistance, they just need to be a reasonable match.

 

[MJPAudio]

If you buy 4 tubes that are all from the same manufacturing batch you should be fine.
Tell Digikey/Mouser, this is a requirement for the sale.
They will make sure you get what you ask for.

If you are nervous buy 5 tubes, then just sell off what you don't need.

I just emailed mouser for 6 tubes from the same batch that should give me 150 pieces.

Thanks for your help