Diyaudiostore IRFP240

[uchu007]

Hello,
Here are the curves of the transistors bought on the store, what did you think of pairings? The measurements were made with the peak atlas dca75 pro.
Thank you

 

[Dennis Hui]

For their intended usage you probably will want to look at curves at significantly higher current levels.

 

[uchu007]

I just wanted to check if the pairing was done well

 

[uchu007]

Nobody to answer me ?

 

[Bare]

I bought from Mouser and the supplied 240's were sequentially mfg'd. Suggesting that they were Similar if not identical.
Not heard any audible artifacts to suggest otherwise

 

[fabrice63]

Hello,
Here are the curves of the transistors bought on the store, what did you think of pairings? The measurements were made with the peak atlas dca75 pro.
Thank you

I have too , bought the dca75 pro ,time ago for the same purpose ( I thought !! ) , but forget about it , it's absolutely not made for such job , get there :

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

.

 

[nigelwright7557]

They are meaningless at that current compared to normal use.
You need to build a tester that works at least at 1 amp.

I tend to buy in one batch from same supplier then they should be from same die and so should be close.

 

[Nelson Pass]

IMHO you can do fine at 100 mA.

 

[wdecho]

They are meaningless at that current compared to normal use.
You need to build a tester that works at least at 1 amp.

I tend to buy in one batch from same supplier then they should be from same die and so should be close.

There are 25 to a sleeve and I have found all 25 to be really close, at least the last time I bought IRFP240 and IRFP9240.

 

[uchu007]

IMHO you can do fine at 100 mA.

Ok thank you, for your answer. I thought that the paired transistors on the diy audio store was close because normally when have the pair have the fact on all the curves and not only on some points of polarization so has any current of test should have a similarity of the transistor already paired

 

[Nelson Pass]

Matching at the intended operating voltage and current is ideal, but
generally requires heat sinking and more time. At a lower level
(like 100 mA) you can still get a pretty good number without much
thermal drift.

 

[uchu007]

Matching at the intended operating voltage and current is ideal, but
generally requires heat sinking and more time. At a lower level
(like 100 mA) you can still get a pretty good number without much
thermal drift.

OK ,
thank you Nelson I understand you I thank you

 

[nigelwright7557]

Matching at the intended operating voltage and current is ideal, but
generally requires heat sinking and more time. At a lower level
(like 100 mA) you can still get a pretty good number without much
thermal drift.

It depends if the relationship between turn on voltage and pass current is linear across the working current range for each transistor.
If it is then you can get away with a lower current.
If not then the transistors could become misloaded at different currents to the test current.

As the current gets higher it takes a higher voltage to push out the extra current.
I have seen lateral mosfet amps that use this voltage to be limited by a Zener to limit max current.

I have a semiconductor analyser which works at a few mA and its readings usually come out way to high. I am getting massive gain readings for transistors as against the datasheet.

 

[Bfpca]

To avoid the thermal drift problem I developed a method to match IRFP240s by mounting them to a temp regulated aluminum plate and using high current pulses. I then convert the resulting output voltage to a VGS reading. Doing some basic statistical analysis on this method it had very good precision comparable to using a constant high current and heatsink mounting the part. It is much faster though.