Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: kagliostro on June 15, 2011, 03:50:06 pm
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Please I need a technical lesson
I would like to learn how to understand more the data on tube datasheet
have you a link for that or can you give news as to correctly afford the read of a datasheet ?
Many Thanks
Kagliostro
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A couple of members, including Butterylisciuos, gave some great tutorials (to me among others) on load lines. :worthy1: I can't find the thread(s). :dontknow: Maybe someone will remember. :think1:
Meanwhile, what specifically do you want to address? :dontknow: Usually the first hurdles are the max ratings, then tables of typical operation. Then there's the dreaded tube curves. :BangHead:
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What are you trying to figure out?
Here's the best tube data search I've found:
http://www.mif.pg.gda.pl/homepages/frank/vs.html (http://www.mif.pg.gda.pl/homepages/frank/vs.html)
Enter 6L6, then select the G.E. 1963 sheet for a 6L6GC.
The "Maximum Ratings" are always useful. On some older data sheets, they refer to "Design Center Maximum" IIRC. It's not quite the same thing, and I think the "Design Center" figures typically are lower.
On page 2, it shows typical operating conditions. A treasure trove of good info! Unfortunately, the supply voltages tend to be lower than what you find in modern amps.
Then you hit the graphs. I still have a hard time understanding these because they typically show 3 variables at the same time. Merlin a.k.a. "Valve Wizard" has great info on using the graphs HERE (http://www.freewebs.com/valvewizard1/Common_Gain_Stage.pdf) for triodes. His pentode section isn't about power tubes, but helpful:
http://www.freewebs.com/valvewizard/pentode.html (http://www.freewebs.com/valvewizard/pentode.html)
I used to have a link to an essay called "Understanding Load Lines" but can't find it. Anybody else familiar with it?
Hope this helps,
Chip
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PRR has a way of presenting things to people that make it easy to understand. I was reading a
thread of his a while back and thought some other people would find it useful at the time...
so I asked PRR if I could recreate this thread in a pdf this a few years back, he said ok, so here it is again...
LoadLinesbyPRR...
http://theairtightgarage.com/gallery/loadlinesbyprr.pdf (http://theairtightgarage.com/gallery/loadlinesbyprr.pdf)
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PRR has a way of presenting things to people that make it easy to understand. I was reading a
thread of his a while back and thought some other people would find it useful at the time...
so I asked PRR if I could recreate this thread in a pdf this a few years back, he said ok, so here it is again...
LoadLinesbyPRR...
http://theairtightgarage.com/gallery/loadlinesbyprr.pdf (http://theairtightgarage.com/gallery/loadlinesbyprr.pdf)
Many thanks to Triode and PRR!
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Many thanks to all for the given advices and infos
tables of typical operation. Then there's the dreaded tube curves
those are two things that I would like to understand better
Many thanks also for the given links with first class infos
Kagliostro
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The opening chapters of Merlin's book on pre-amp design is very good on how the curves relate to the circuit. As a newbie I got a lot out of it.
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The opening chapters of Merlin's book on pre-amp design is very good on how the curves relate to the circuit. As a newbie I got a lot out of it.
Merlin is nice enough to provide the entire first chapter of his preamp book here:
http://www.freewebs.com/valvewizard1/Common_Gain_Stage.pdf (http://www.freewebs.com/valvewizard1/Common_Gain_Stage.pdf)
That's what I intended to link to in my earlier post, and it is good albeit without the stained napkin in PRR's discussion :wink:
Chip