I'm looking at ordering fets and would like to know which I should order.
Price is about the same so that isn't an issue.
The main issue for me is which sounds better???????
The 240 appears to be a higher current device so I'm thinking that is the best choice unless I'm convinced otherwise.
I will make sure they are all from the same lot.
Also, I no longer see the "N" versions listed on Newark's site. What's up with that? Are the N's the only versions now available or has IR dumped them?
On a side note, does anyone know a reasonably priced source for IRF240's? $11.00 each from Newark seems a bit steep....
Thanks for the help!!!!
Price is about the same so that isn't an issue.
The main issue for me is which sounds better???????
The 240 appears to be a higher current device so I'm thinking that is the best choice unless I'm convinced otherwise.
I will make sure they are all from the same lot.
Also, I no longer see the "N" versions listed on Newark's site. What's up with that? Are the N's the only versions now available or has IR dumped them?
On a side note, does anyone know a reasonably priced source for IRF240's? $11.00 each from Newark seems a bit steep....
Thanks for the help!!!!
Steve,
Most people use the 240 instead of the 244. I buy mine at Digikey. The only parts available now are the lead free ones and someone along the supply chain has taken the opportunity to almost double the price to about $4.50 (for 1). A bit of rip really.
Fairchild no longer lists the IRFP240 but shows the FQA19N20C as a sub. It looks like a nice part. Mouser charges $1.92 for 1.
Cheers,
Graeme
Most people use the 240 instead of the 244. I buy mine at Digikey. The only parts available now are the lead free ones and someone along the supply chain has taken the opportunity to almost double the price to about $4.50 (for 1). A bit of rip really.
Fairchild no longer lists the IRFP240 but shows the FQA19N20C as a sub. It looks like a nice part. Mouser charges $1.92 for 1.
Cheers,
Graeme
You can always order direct from International Rectifier, thats the easiest, buy a tube of 25 and chances are they'll be from the same batch, which usually yields better matches.
-john
International Rectifier
edit: No stock of Irfp240 at IR, but plenty of the lead free pkg
-john
International Rectifier
edit: No stock of Irfp240 at IR, but plenty of the lead free pkg
Attachments
Mega Amp John-
Nice tip about IRF--I wish I had known about that last week.....
I think one of the most important criteria listed for selecting mosfets is the input capacitance. IRFP 240's are in the 1200pf range, IRFP 244's, (and 250's) are in the 2400pf range (if I recall the numbers correctly from the datasheets). You get more more high frequency distortion with higher input cap.
TO220 devices, such as the IRFP 634's and 9630's are in the 600pf input capacitance range, but offer about half the power handling. I used the 634's in an A-75 and also in an aleph mini, and they sounded just fine. (bias current in the mini .66 amps for each device).
The TO220's require a number 4 mounting screw if they are to be isolated from the heatsink -- not so easy to tap, so if you are using a lot of output devices, go with the TO247's.
JJ
Nice tip about IRF--I wish I had known about that last week.....
I think one of the most important criteria listed for selecting mosfets is the input capacitance. IRFP 240's are in the 1200pf range, IRFP 244's, (and 250's) are in the 2400pf range (if I recall the numbers correctly from the datasheets). You get more more high frequency distortion with higher input cap.
TO220 devices, such as the IRFP 634's and 9630's are in the 600pf input capacitance range, but offer about half the power handling. I used the 634's in an A-75 and also in an aleph mini, and they sounded just fine. (bias current in the mini .66 amps for each device).
The TO220's require a number 4 mounting screw if they are to be isolated from the heatsink -- not so easy to tap, so if you are using a lot of output devices, go with the TO247's.
JJ
http://www.tech-diy.com/hexfets.htm
As they are already matched sets you save by only buying what your project requires.
Looks swell on paper...anyone daring to
a non IR fet?
-------------------------------------------FQA19N20C IRFP240
gFS Forward Transconductance--------- 10.8 ------------ 6.9
Ciss Input Capacitance------------------- 1080 pF ------ 1300 pF
PD Power Dissipation---------------------- 180 W -------- 150 W
RθJC Thermal Resistance------------------ 0.69 °C/W -- 0.83 °C/W
-Mal
As they are already matched sets you save by only buying what your project requires.
Looks swell on paper...anyone daring to
a non IR fet? -------------------------------------------FQA19N20C IRFP240
gFS Forward Transconductance--------- 10.8 ------------ 6.9
Ciss Input Capacitance------------------- 1080 pF ------ 1300 pF
PD Power Dissipation---------------------- 180 W -------- 150 W
RθJC Thermal Resistance------------------ 0.69 °C/W -- 0.83 °C/W
-Mal
I for one would not be afraid to try the FQA19N20C. They look pretty nice - both spec and price-wise. They are listed by Fairchild as a direct sub. I have used the Fairchild SFP9240 quite successfully. It is their sub for the IRFP9240.
Mike is right. The Fairchild parts being discussed here come in the TO-3P package and won't take a 6-32 bolt. You need to use an M4 bolt instead. This has been discussed before.
Cheers,
Graeme
Mike is right. The Fairchild parts being discussed here come in the TO-3P package and won't take a 6-32 bolt. You need to use an M4 bolt instead. This has been discussed before.
Cheers,
Graeme
Fairchild does not list the FQA19N20 as being a current piece. The FQA19N20C (note the C suffix) is the current part. The parts do not spec the same. The "C" is, unfortunately, unobtanium.
I generally try to avoid end-of-life-cycle parts because you can't just service them by dropping in one part--you have to replace the entire bank of parts. What would normally be a $3 repair suddenly becomes a $100 repair. If you have to buy a bunch of parts to select matched devices, it gets considerably worse. I don't like that kind of surprise.
Grey
EDIT: The SFH9240 is "not recommended for new design." Approach these parts with caution.
I generally try to avoid end-of-life-cycle parts because you can't just service them by dropping in one part--you have to replace the entire bank of parts. What would normally be a $3 repair suddenly becomes a $100 repair. If you have to buy a bunch of parts to select matched devices, it gets considerably worse. I don't like that kind of surprise.
Grey
EDIT: The SFH9240 is "not recommended for new design." Approach these parts with caution.
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