Genuine 2N3773s are workhorses, I like them.
~250W 100mS SOA at Tc=70°C. One pair of them in quasi-complementary configuration does 100W-RMS safely.
Attention, for audio amplifiers only the epitaxial type's are OK (Ft=4MHz)! The homotexial (Ft=0.5...1Mhz) 2N3773s are only sufficient as series pass transistors in linear PSUs.
Somewhere I've got an old Mot (?) datasheet that shows Ft curves too. Anyone interested? Then I'll dig up my winchester.
~250W 100mS SOA at Tc=70°C. One pair of them in quasi-complementary configuration does 100W-RMS safely.
Attention, for audio amplifiers only the epitaxial type's are OK (Ft=4MHz)! The homotexial (Ft=0.5...1Mhz) 2N3773s are only sufficient as series pass transistors in linear PSUs.
Somewhere I've got an old Mot (?) datasheet that shows Ft curves too. Anyone interested? Then I'll dig up my winchester.
How does one tell the difference between homo & epi?
1.5A continuous @ 100Vce is almost unique among 150W devices. And even better ONsemi supply 100% tested for this parameter.
A real workhorse.
ps,
ONsemi show near 400W upto 80Vce for 100mS SOA
Which probably explains why my Crimson1704 1pair Quasi complementary claim 170W into 4r0 and I have tested it to 200W into 4r0 in the short term (~2seconds)
1.5A continuous @ 100Vce is almost unique among 150W devices. And even better ONsemi supply 100% tested for this parameter.
A real workhorse.
ps,
ONsemi show near 400W upto 80Vce for 100mS SOA
Which probably explains why my Crimson1704 1pair Quasi complementary claim 170W into 4r0 and I have tested it to 200W into 4r0 in the short term (~2seconds)
Andy L. Francis said:
The hometaxials are good for audio - they're my first choice for single-ended class A where you don't have to worry about them not switching off fast enough. Got a bunch of 2N6254's and 6259's laying around that will eventually go into a heater or two. I don't think RCA ever made epitaxial versions of those.
Hi Andrew,
That 400W is valid at Tc=25°C, that's why I wrote only 250W (Tc~70°C).
I've found that designing with 100mS SOA is safely, no need to stay under the DC SOA line.
What a pity Onsemi doesn't gives the 100mS SOA of their MJ15003, MJ15022 etc... devices! I should say it's a shame! With these devices I use to design under the DC SOA line because of safety reasons. I'm using 60°C phase margin in my calculations.
Wg_ski,
Sorry, you're right - I need a coffee.
I remember I had a handful of hometaxial (I'm not sure they were hometaxials, the seller claimed that) 3773s, I bought them for a song for a 13.8V/~20A HAM PSU project. Then after many years I modified this PSU to class-A audio amplifier (J. Linsley Hood 10W) and the amplifier worked well until I sold it to an audiophile.
That JLH amplifier had a single-ended OP stage configuration.
That 400W is valid at Tc=25°C, that's why I wrote only 250W (Tc~70°C).
I've found that designing with 100mS SOA is safely, no need to stay under the DC SOA line.
What a pity Onsemi doesn't gives the 100mS SOA of their MJ15003, MJ15022 etc... devices! I should say it's a shame! With these devices I use to design under the DC SOA line because of safety reasons. I'm using 60°C phase margin in my calculations.
Wg_ski,
Sorry, you're right - I need a coffee.
I remember I had a handful of hometaxial (I'm not sure they were hometaxials, the seller claimed that) 3773s, I bought them for a song for a 13.8V/~20A HAM PSU project. Then after many years I modified this PSU to class-A audio amplifier (J. Linsley Hood 10W) and the amplifier worked well until I sold it to an audiophile.
That JLH amplifier had a single-ended OP stage configuration.
burbeck said:
Now those are the real deal. I've aquired a few over the years and used them with no trouble. The real one are old (25-30 years is about right). Flip them over and you'll be able to tell easily. They should have the copper heat spreader coin that the D424 and other devices from that era did - and with the Jap units you can see from the bottom side where it's bonded in.
Please let me know the models from your various ages of amplifiers - thank you.
I got this set in in my pyle of parts for about 20 years ...
Dunno if Chinese guys make fakes back in time ... !
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Dunno if Chinese guys make fakes back in time ... !
Only RCA i got is 2N3055, will test them both in last "quad 405 clone" ...
Also got me some old "JPS" 2N3773 and some "Toshiba" 2SD424 ...
All are NOS, never mounted, will see what brand - model will perform the best ...
And yes, got me some old 2n3055 marked wirh bold "Beta" - "β" ...
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