MT-200 transistors, one last save, maybe.

The only place the Sankens have an advantage over the TO-264s are on the SOA at high Vce or very low Vce, plus the extra surface area. The 2SC3264 doesn't become SOA limited until 80v, which is pretty impressive. The MJL4302/MJL4281 come the closest in this regard, but still only have about half power handling capability at the higher Vce. So they may not be ideal replacements for Parasound JC-1s driving Apogees.
 
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TO-247 looks like it's going to be next on the chopping block, judging from what is available at Digi-Key and Mouser.

TO-247 same as TO-3P

2SA1962(R, O) 250v 17A 30Mhz 130W TO-3P: 512-2SA1962OTU
2SC5242(R, O) 250v 17A 30Mhz 130W TO-3P: 512-2SC5242OTU
 
Interesting post by Utima Thule at DIYaudio:
http://www.diyaudio.com/forums/soli...ng-mt200-power-transistors-2.html#post5333091

"Just IMHO I don't miss the MT200 packages.
smile.gif

One can get roughly 6 pcs of equivalent TO-3P devices for the same price as 4 pcs of MT200, inside it the silicon substrate is still attached onto a TO-3P metal base which in turn is attached to a larger MT200 base, paying ~2 €$£ more for extra metal and plastic huh?
biggrin.gif


Borrowing a picture from this link:
2SA1215 2SC2921, identify genuine and fake
2SA1215-2SC2921Y-1.jpg 2SA1215-2SC2921Y-3.jpg

What I think is going on here is that by probably soldering the TO-3P metal base to a larger
metal base with 2 screws there is good thermal conductivity to the larger base which provides
more area to the insulator with 2 screws for better contact for lower overall thermal resistance.
It would be very interesting to find out if there are types that employ the same die, perhaps have a cross reference table.
People have probably seen where a bar is used over single screw packages to provide more
even pressure for lower thermal resistance. Two screws from the MT200 mount could be used
with a bar or channel to provide pressure on a replacement TO-3P device.
 
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What I think is going on here is that by probably soldering the TO-3P metal base to a larger
metal base with 2 screws there is good thermal conductivity to the larger base which provides
more area to the insulator with 2 screws for better contact for lower overall thermal resistance.
It would be very interesting to find out if there are types that employ the same die, perhaps have a cross reference table.
People have probably seen where a bar is used over single screw packages to provide more even pressure for lower thermal resistance. Two screws from the MT200 mount could be used
with a bar or channel to provide pressure on a replacement TO-3P device.

Yes..some use that approach for applying pressure to multiple devices.

final%2Btransistor%2Bamplifier.jpg
 
Interesting post by Utima Thule at DIYaudio:
http://www.diyaudio.com/forums/soli...ng-mt200-power-transistors-2.html#post5333091

"Just IMHO I don't miss the MT200 packages.
smile.gif

One can get roughly 6 pcs of equivalent TO-3P devices for the same price as 4 pcs of MT200, inside it the silicon substrate is still attached onto a TO-3P metal base which in turn is attached to a larger MT200 base, paying ~2 €$£ more for extra metal and plastic huh?
biggrin.gif


Borrowing a picture from this link:
2SA1215 2SC2921, identify genuine and fake
View attachment 1115295 View attachment 1115296

What I think is going on here is that by probably soldering the TO-3P metal base to a larger
metal base with 2 screws there is good thermal conductivity to the larger base which provides
more area to the insulator with 2 screws for better contact for lower overall thermal resistance.
It would be very interesting to find out if there are types that employ the same die, perhaps have a cross reference table.
People have probably seen where a bar is used over single screw packages to provide more
even pressure for lower thermal resistance. Two screws from the MT200 mount could be used
with a bar or channel to provide pressure on a replacement TO-3P device.

That's interesting, I had no idea that they were basically a $7 TO-3P.
Most of my amps are running MT200s (though they are the older, faster Toshiba 1333/3870) but I've still stocked up on spare Sankens just in case I get stupid and manage to blow one up somehow.
 
Sounds pretty sturdy. One of your own design?
My old workhorse Denon POA 2400A only has two pair/channel.
 
That's interesting, I had no idea that they were basically a $7 TO-3P.
Most of my amps are running MT200s (though they are the older, faster Toshiba 1333/3870) but I've still stocked up on spare Sankens just in case I get stupid and manage to blow one up somehow.

They are a TO-3P with a heat spreader, so we pay for the extra labor to add the heat spreader.
Not sure if the die are the same.
 
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