I have a RCA transistor Manual Technical Series SC-11 copywrite 1964. It has a 2n3055 in it. Vceo 60 Ic max 15 A Pd case 25 C 115 w Vcesus (Rbe=0 Ic=.2A) 60 vcesat (IC=4 Ib=.4) 1.1v
Current transfer ratio (Ic=4 Vce=4) 20 to 70 . There are transfer curves and Vbe to Ib cirves.
No Ft spec.
FIgure 11-11 in the back, high quality 25 w audio amplifier, has push pull 2n2147 outputs and an interstage transformer after the 2n2148 input transistor.
I don't have a camera since they are all made now in a place I don't buy from.
I didn't start work in electronics until 1976 so I retrieved this book out of the trash.
Current transfer ratio (Ic=4 Vce=4) 20 to 70 . There are transfer curves and Vbe to Ib cirves.
No Ft spec.
FIgure 11-11 in the back, high quality 25 w audio amplifier, has push pull 2n2147 outputs and an interstage transformer after the 2n2148 input transistor.
I don't have a camera since they are all made now in a place I don't buy from.
I didn't start work in electronics until 1976 so I retrieved this book out of the trash.
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This SC-11 manual is anywhere online here as I know (I had upload as PDF in post #246).
But I am still looking for the very first announcements and advertisements for 2N3055 in electronic magazines so as brochures from RCA.
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any news concerning first announcements and advertisements for 2N3055 in electronic magazines so as brochures from RCA ?
http://bitsavers.informatik.uni-stuttgart.de/components/rca/_dataBooks/1978_RCA_Power_Devices.pdf
from 1978, inside some schematics
from 1978, inside some schematics
Not exactly an amplifier, but I think it's worth posting it:
Here you can see the initial bitter flowers of the "importozameshenye/импортозамещение". This is the moment when the comrades realized that the crap USSR transistors can be replaced by the reliable Western ones 🙂.
And all this process finally went to the point where there were no possible ways for building the Russian assault weapons except than using the Western IC/transistors/etc.
Here you can see the initial bitter flowers of the "importozameshenye/импортозамещение". This is the moment when the comrades realized that the crap USSR transistors can be replaced by the reliable Western ones 🙂.
And all this process finally went to the point where there were no possible ways for building the Russian assault weapons except than using the Western IC/transistors/etc.
Hello tiefbassuebertr
Following a hunch I looked up a couple more mags.
Found one. Not the one I originally saw, but a full page ad.
Page 67 in Industrial Electronics magazine. Available on World Radio History, UK magazine section, January 1965.
Probably advertised in the USA previous year.
The 4B date code probably means February 1964.
Following a hunch I looked up a couple more mags.
Found one. Not the one I originally saw, but a full page ad.
Page 67 in Industrial Electronics magazine. Available on World Radio History, UK magazine section, January 1965.
Probably advertised in the USA previous year.
The 4B date code probably means February 1964.
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Original 2N3055 non fake are wonderful transistors
using them in my JLH 15w class A amplifier ...
using them in my JLH 15w class A amplifier ...
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I think in November 1996 they should have known that a supply voltage of ±50 V puts excessive stress on most of the involved semicinductors and that TR4 multiplies it's Vbe by a factor of not more than 3.3, while 4 Vbe's are needed to bias the power devices at all.
Best regards!
I wonder why they didn't populate Czechoslovakian (Tesla) KD617's, which are superior than 2N3055's? And do you know what is shown in your pic?
Best regards!
@Kay P - the Vbe you discuss does not mean that the quiescent current could not be set correctly. Your Vbe calculation assumes that all the Vbe's are the same. They might be if all the transistors were the same and operated at the same voltage and current, but they are different. The BD139 is running at a (guesstimated) 10mA, but the driver transistors are hugely over-rated - 75W, 12A and would pass a respectable current with a relatively low Vbe. The same for the output transistors. (Also, the drivers are epitaxial base 3MHz and not ideal. They seem to have worked in this application though. Probably chosen for 100V rather than high frequency)
You are correct in supposing that 4Vbe's are required, but in many circuits like this, that is not achieved. A different bias circuit could deliver the necessary compensation, but I suspect the quiescent current would be settable.
You are correct in supposing that 4Vbe's are required, but in many circuits like this, that is not achieved. A different bias circuit could deliver the necessary compensation, but I suspect the quiescent current would be settable.
The harman-kardon citation 12 suggests the output transistors were 40636. These seem to have the same specification as the 2N3055 except for Vceo. They could just be a selected 2N3055, I guess. Does that count?
Me too 😉 ! Anyway, I've always been wondering about their lack of stability and overload ruggedness, despite their current protection. But it has become clear to me in the meantime: The BC107B's and BC177B's (or nowadays' BC547B's and BC557B's) in the predriver section can't cope with supply voltages of more than 45 Vdc. Maybe the EQUA is more stable with transistors of higher Vce ratings.
Best regards!
Do you have the schematic and PCB you can post up? I remember etching the PCB’s I think 1976 or 1977
I'm sure I'd find the complete article (in German) somewhere if I'd search long enough, but due to possible copyleft infringements I'm not too sure if it's allowed to post it here.
Best regards!
Best regards!
Thanks. Looks familiar and I recognise a lot in the circuit. I think the English language version came out a year or two later, but I might be mistaken.
Good memories. I knew nothing about grounding, wire routing or anything like that. Mine hummed!
Good memories though!
😊
Good memories. I knew nothing about grounding, wire routing or anything like that. Mine hummed!
Good memories though!
😊