Thanks for the detailed answers. Unfortunately I get lost in following all these considerations. Basically I would just like to know what substitutes you would suggest I use in this circuit with a reasonable degree of safety.
Those MJHs are the “right” transistors to use, if you are going to the TO-247 package. They won’t be any more or less susceptible to runaway than the original parts were. But if you did find that to be an issue you’d need to look into it.
Beware of ST parts which have been discontinued. They quit making TO-3’s years ago, with the very last hold-out being the 2N3055. The 2N6484/7 disappeared from their portfolio long before ON’s did. Fakes are everywhere.
Beware of ST parts which have been discontinued. They quit making TO-3’s years ago, with the very last hold-out being the 2N3055. The 2N6484/7 disappeared from their portfolio long before ON’s did. Fakes are everywhere.
I'm resuming the discussion for a further question.
After we had already established with wg_ski for the MJH and I was about to order them, someone proposed the Sanken 2SD2083 / 2SB1383 pair.
What do you think?
Thanks
After we had already established with wg_ski for the MJH and I was about to order them, someone proposed the Sanken 2SD2083 / 2SB1383 pair.
What do you think?
Thanks
Good luck getting those. Sanken discontinued those some time ago. The earlier proposed versions are better as amplifiers, too. The D2083 was good for very low voltage, high current operation. I was using them in class G where the rail tiers were 27.5V. Those newer versions have far better linear SOA, and just as much current gain at 15A.
I bought these in local shop.
I was worried as housing isn't the same on NPN and PNP, opened 2 to see die, nice large and neat, so that was ok. Tested all at 120V for breakdown and leakage , also ok. Hfe very uniform 11.000 for P and 13,000 for Y class. I did not sweat that P and N has slightly different gain as this is not my main amp and it has huge feedback, they are fine. But Im not sure if you need such fast transistors for class A, with great risk of buying counterfeits...
By the way, I have original MJ2501/3001 in drawer if needed to just repair.
I was worried as housing isn't the same on NPN and PNP, opened 2 to see die, nice large and neat, so that was ok. Tested all at 120V for breakdown and leakage , also ok. Hfe very uniform 11.000 for P and 13,000 for Y class. I did not sweat that P and N has slightly different gain as this is not my main amp and it has huge feedback, they are fine. But Im not sure if you need such fast transistors for class A, with great risk of buying counterfeits...
By the way, I have original MJ2501/3001 in drawer if needed to just repair.
You were lucky.
I just did a search and on Mouser and digikey they are obsolete, unfortunately.
as I already explained, I can no longer use TO3 packaged power amps because I replaced the heat sinks with larger ones and without drilling for that case.
I just did a search and on Mouser and digikey they are obsolete, unfortunately.
as I already explained, I can no longer use TO3 packaged power amps because I replaced the heat sinks with larger ones and without drilling for that case.
The D2560/B1647 is the modern version. Still current production, although availability is poor in small quantity. D2083/B1383 are in fact gone.
Define “better”. You aren’t going to find D2560’s at Digikey anymore, unless you preorder 1000 of them. You can buy two pairs of the MJH’s and have them this week. That’s “better” if the MJH’s are sufficient for the task. They are. Problem solved.
If you really really want original Sanken darlingtons, you can go different route and get old surround receiver (save it from scrap yard for instance)
I got Sony STR-DG700 for 10 Euro and inside are 6 channels with MN2488/MP1620 pairs (10A - 150W - 55kHz), so 6 pairs and for sure these are genuine and from same grade, if not even selected.
I got Sony STR-DG700 for 10 Euro and inside are 6 channels with MN2488/MP1620 pairs (10A - 150W - 55kHz), so 6 pairs and for sure these are genuine and from same grade, if not even selected.