>That will be hard to blow up!
>
>** No hard at all.
Well harder than an MJE2955. Harder than a 2N66609. They make oe really tougher pair, MJ2XXXX something. Probaably use those in Krells, just because. I mean they got like 128 output transistors ... nevermind.
>I once had boxes of dead ones lying around - mostly extracted from >amplifiers like the Phase linear 400 and 700 mk2s.
So those were all the complementary ones,not the quasi like I had. It was a two but still all NPN outputs. And of course when I got it and took it apart I found like four different types or putouts in it. Shit, this is only a 400 so it only has three pairs per channel.
>Like any bi-polar, they had limited "safe area" of about 2A at 80V >for 0.5 seconds and much less at higher voltages
Well it's not quite THAT bad, but... People do not get it sometimes. "It will be hard to blow that". sure, but if you get it hot enough it will fry. All transistors derate power handling. By 200ºC they can dissipate zero watts. Hot enough those badass MJs will fry, perhaps even from bias current. Not even one watt.
The way I take on it it that the thermal resistance to case is what limits that. The die can get so get hot so fast that it doesn't matter how good the heatsink is, it is not moving the heat FAST enough. That 200ºC is the JUNCTION temperature. And even with the best of mounting techniques, I mean run a bead or blob and squish it out so there are no air pockets, do it on clean surfaces and make it tight as hell, the thermal resistance is still atrocious.
One of the things I do understand some is power. I make a point of when I fix an amp it stays fixed. So I WILL use MJ15024s ans 15023s in fifty watt per channel amps.
Yes the power rating derates like an other, but this one you have to put in a deep fryer. LOL (not really) But then 375ºF is only 190ºC so we got ten degrees to go !
>The lateral Mosfets made by Hitachi that come along in the 1980s >were enormously more rugged.
If you got spares to spare I'll take them. But I don't remember right now, were they the ones with the really low Vgs or the ones you can parallel with no source resistors ?
And you know source resistors don't work worth a fuck on MOSFETs. I got a circuit that can balance a bank of the much better but, why ? Many people could do the same thing.
Ahh, I probably don't have to worry about this right now. A guy is bringing a Tascam, bodybuilder model four track ¼" four track.
Nice to do something different once in a while.
ACK ! I just looked at the time and I missed my shootemup show of the day. Dammit. Fucking Aussies.