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How many watts from a 2879
- Thread starter 543_Dallas
- Start date
That was a picture of a brand new transistor that had never been installed in anything and the whole set of 8 had an identical dimple preventing even heat dissipation. All eight needed the same treatment before installation.
I used one of these to surface all eight transistors. I did that part myself. Yes Mark did the rebuild.
Smith's DCS4 4-Inch FINE & COARSE Diamond Combo Sharpening Stones
Surface imperfections are one reason they use Thermal Grease. That dimple occurs when they attach the transistor die to the mounting flange.
Thermal grease is useless with a 1mm dimple. Both surfaces must mate together perfectly with a recommended tolerance of 0.03 mm, and squeezing out as much of that thermal grease as possible for the heat dissipation to be most effective. A lot of copper had to be removed just to allow the center to make physical contact with the heatsink.
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I agree. The heatsink grease is only 4 times better than air so that would not fill a large gap properly. I have lots of experience machining parts for thermo-electric modules and the tolerances are tight. I would use an Arkansas Stone to smooth out the bottom after roughing it in with the diamond file.
I like to check them with a flat file. I don't worry so much about new pills with a high spot in the middle of the die as I do with used pills that have the tabs bent downward from the last install. I think they get bent when someone puts a thick blob of compound under the center and tightens the screws down too quickly.
I try to use a very thin and even layer of heatsink compound. Then slowly tighten the screws while pressing on the top of the pill.Maybe it doesn't make a real difference but it makes me feel better.
I try to use a very thin and even layer of heatsink compound. Then slowly tighten the screws while pressing on the top of the pill.Maybe it doesn't make a real difference but it makes me feel better.
I use a small section of perf board like a notched trowel with the edge open to approximately 50% or more. Then you put the transistor down and rotate it back and forth. There is very little grease under the transistor at this point. Run a few thermal cycles on it and then re-tighten.
Well it was meant as a joke because all the builders profess to have "Secret Knowledge" that allows them to get more power than any other fool with plumbers soldering iron or a Sears Craftsman Soldering Gun! LOL As if electrons could be fooled by the esoteric! LOL
No beer for me right now I am juice fasting. In 5 days time, my pulse has dropped 15-20 beats a minute and my blood pressure has dropped to 117/70 my pulse throughout the day is about 62 beats a minute. I walked 2 miles and then run up the steps to my front door. I took pulse as and BP as soon as I got in the door and my blood pressure was the same as above and my pulse was 82 beats a minute after power walking 2 miles. Taking the highest dose of hypertension ACE II's and an Alpha blocker I am lucky to be in the 120-140 over 80 range.
I know my hematocrit is fine and my hydration is good because on top of the fresh juice I am drinking my normal volume of tea and coffee and water. I am also weighing myself each morning and using bioimpedance to keep track of hydration.
So sorry if you guys either did not get my arcane joke or did not find it funny. My humor tends to run to the dark side and dry and I do love making use of science, religion and political references that are obscure or arcane. At least I did not make a math joke! LOL
Oh and Dave457 you do not understand the word ignorant and it's meaning I recommend you get out a dictionary and take a gander at it! If I am not at all ignorant while there are a good many things I know nothing about I know more than most about most things! When it comes to the arcane, history, major religions, obscure religions, occult, the teaching of most of the secret schools, science, philosophy, chemistry, anatomy and physiology, psychology, martial arts, cooking, tool and die, material sciences, aviation, automotive industry, tribology, competitive shooting sports, music,public speaking, the design and building of musical instruments from scratch and a good many other things I have very high mastery. My weakest subjects are writing, spelling, punctuation, and electronics. I am working on weakness in electronics but I fear Tesla and Maxwell have little to fear from me! LOL
I can generally sit down with anyone and talk about almost any subject and keep up! Unlike most people, I do not have digital tv, cable or satellite in my home. When I am not working or doing other things that I have to do I am reading and doing. I read more books non-fiction books in a year than most people read in a lifetime. Between insomnia and ADHD I get a lot done!
No beer for me right now I am juice fasting. In 5 days time, my pulse has dropped 15-20 beats a minute and my blood pressure has dropped to 117/70 my pulse throughout the day is about 62 beats a minute. I walked 2 miles and then run up the steps to my front door. I took pulse as and BP as soon as I got in the door and my blood pressure was the same as above and my pulse was 82 beats a minute after power walking 2 miles. Taking the highest dose of hypertension ACE II's and an Alpha blocker I am lucky to be in the 120-140 over 80 range.
I know my hematocrit is fine and my hydration is good because on top of the fresh juice I am drinking my normal volume of tea and coffee and water. I am also weighing myself each morning and using bioimpedance to keep track of hydration.
So sorry if you guys either did not get my arcane joke or did not find it funny. My humor tends to run to the dark side and dry and I do love making use of science, religion and political references that are obscure or arcane. At least I did not make a math joke! LOL
Oh and Dave457 you do not understand the word ignorant and it's meaning I recommend you get out a dictionary and take a gander at it! If I am not at all ignorant while there are a good many things I know nothing about I know more than most about most things! When it comes to the arcane, history, major religions, obscure religions, occult, the teaching of most of the secret schools, science, philosophy, chemistry, anatomy and physiology, psychology, martial arts, cooking, tool and die, material sciences, aviation, automotive industry, tribology, competitive shooting sports, music,public speaking, the design and building of musical instruments from scratch and a good many other things I have very high mastery. My weakest subjects are writing, spelling, punctuation, and electronics. I am working on weakness in electronics but I fear Tesla and Maxwell have little to fear from me! LOL
I can generally sit down with anyone and talk about almost any subject and keep up! Unlike most people, I do not have digital tv, cable or satellite in my home. When I am not working or doing other things that I have to do I am reading and doing. I read more books non-fiction books in a year than most people read in a lifetime. Between insomnia and ADHD I get a lot done!
In all your ramblings you never confirmed or denied the rumor I asked you about in another thread. Are you the telestar guy that builds amps in plastic cases?
60 watts for decent imd, per the spec sheet....if ran at the spec sheet voltage and biased as specified in the spec sheet.
I thought the input and testing from w8ji was interesting.
Kenwood TS-50 SSB ham radio uses two 2SC2879 to get 100 Watts PEP.
Total.
They last 25 years or longer that way. The SWR-shutdown protection helps, of course.
I learned to ask wattmeter worshippers how many times they want it to key before it blows up. Five?
Two dozen?
A hundred, or maybe more?
I call this the "KBK" rating of the amplfier, as in how many "Keys Between Kabooms" they want to get.
Not so different from "how many horsepower can I get from eight cylinders?".
Do you want it to last the whole quarter mile? Or twice? Ten shots?
Or do you want it to last one whole round-and-round race before it blows?
Or do you want to drive it to work Monday morning? More than once?
The stress placed on a machine and its parts dictates its service life.
Push it harder. Breaks sooner.
A 2SC2879 is a machine, technically. Converts power from one form to another.
Stress is stress. Whether it's a transistor or a V-8, the same rules apply.
73
Total.
They last 25 years or longer that way. The SWR-shutdown protection helps, of course.
I learned to ask wattmeter worshippers how many times they want it to key before it blows up. Five?
Two dozen?
A hundred, or maybe more?
I call this the "KBK" rating of the amplfier, as in how many "Keys Between Kabooms" they want to get.
Not so different from "how many horsepower can I get from eight cylinders?".
Do you want it to last the whole quarter mile? Or twice? Ten shots?
Or do you want it to last one whole round-and-round race before it blows?
Or do you want to drive it to work Monday morning? More than once?
The stress placed on a machine and its parts dictates its service life.
Push it harder. Breaks sooner.
A 2SC2879 is a machine, technically. Converts power from one form to another.
Stress is stress. Whether it's a transistor or a V-8, the same rules apply.
73
saved me the trouble .
but...
class "C" 88 to 95 each in pairs, a bit more in a tuned circuit single ended.
For a linear transfer function barely 60 watts each in pairs and less if it has to cover several octaves (multiple bands as in general coverage amateur use).
The above is anecdotal personal experience and is under ideal antenna conditions as well as construction techniques.
but...
class "C" 88 to 95 each in pairs, a bit more in a tuned circuit single ended.
For a linear transfer function barely 60 watts each in pairs and less if it has to cover several octaves (multiple bands as in general coverage amateur use).
The above is anecdotal personal experience and is under ideal antenna conditions as well as construction techniques.