Hi all.
I have several hundred 5763 beam power tubes and I'm wanting to build a low power 12-15W SE tube amp, or perhaps SE hybrid. Either way, I'd like to use them as triodes.
Problem is that I don't have the equipment to draw their triode characteristics, nor do I have enough knowledge to derive them from the pentode data.
Is there anyone who can help? Anyone done this and prepared to share? Other suggestions?
Thanks in advance
Sheldon
I have several hundred 5763 beam power tubes and I'm wanting to build a low power 12-15W SE tube amp, or perhaps SE hybrid. Either way, I'd like to use them as triodes.
Problem is that I don't have the equipment to draw their triode characteristics, nor do I have enough knowledge to derive them from the pentode data.
Is there anyone who can help? Anyone done this and prepared to share? Other suggestions?
Thanks in advance
Sheldon
From the datasheet curves, a quick and dirty back of Napkin analysis:
at approx. 82 mA: Mu approx. 20 (from screen V plate curves versus g1 plate curves), gm 10,000 uMho (from g1 plate curves),
so Rp = Mu/gm = 2000 Ohm
translating that to 41 mA operation (tube rated for 50 mA DC max.):
gm' = gm x (I'/I)^.66 so gm' = 6300 uMho
Rp' = Rp x (I/I')^.333 so Rp' = 2520 Ohm
Mu' = gm' x Rp' = 15.9
http://frank.pocnet.net/sheets/049/5/5763.pdf
With a 300 V max B+ rating. Only 41 mA available with +100 V on the plate/screen at 0 V on g1. Only going to get around 4 Watt per tube unless the g1 is taken positive.
at approx. 82 mA: Mu approx. 20 (from screen V plate curves versus g1 plate curves), gm 10,000 uMho (from g1 plate curves),
so Rp = Mu/gm = 2000 Ohm
translating that to 41 mA operation (tube rated for 50 mA DC max.):
gm' = gm x (I'/I)^.66 so gm' = 6300 uMho
Rp' = Rp x (I/I')^.333 so Rp' = 2520 Ohm
Mu' = gm' x Rp' = 15.9
http://frank.pocnet.net/sheets/049/5/5763.pdf
With a 300 V max B+ rating. Only 41 mA available with +100 V on the plate/screen at 0 V on g1. Only going to get around 4 Watt per tube unless the g1 is taken positive.
Last edited:
Hi SA and thanks for this. You obviously know your tubes 
Short of actually plugging one in to a tester, I suppose the easiest way forward to a graph would be to find a triode with similar Mu/gm/Rp and adapt those curves. Does this sound reasonable?
Just for background, I haven't built anything in a very long time. In fact, my PC has been my only music source for years. That, and me playing along with my strat and Fender Classic - the only operational tubes in my house.
So I've decided it's time, however there are space restrictions / female considerations / domestic compromises, if you know what I mean
This means small and neat, which practically translates to lower power or hybrid. I'm happy with that, especially with my next project hopefully a pair of high-sensitivity full-range speakers.
And there you have it.
Regards
Sheldon
Short of actually plugging one in to a tester, I suppose the easiest way forward to a graph would be to find a triode with similar Mu/gm/Rp and adapt those curves. Does this sound reasonable?
Just for background, I haven't built anything in a very long time. In fact, my PC has been my only music source for years. That, and me playing along with my strat and Fender Classic - the only operational tubes in my house.
So I've decided it's time, however there are space restrictions / female considerations / domestic compromises, if you know what I mean
This means small and neat, which practically translates to lower power or hybrid. I'm happy with that, especially with my next project hopefully a pair of high-sensitivity full-range speakers.And there you have it.
Regards
Sheldon
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