That's the suggested OP for triode. Svetlana doesn't make 6P3S tubes. Foton and Reflector mainly. The Soviet datasheets don't include triode data, but as I said it's a 6L6 (not GB,GC) clone. The STC datasheet gives triode information.
http://www.tubezone.net/pdf/6l6g-stc.pdf
http://www.tubezone.net/pdf/6l6g-stc.pdf
Last edited:
I have quite long experience with 6P3S-E, which is a long life type.
I have used these with UL-mode (PP) with the following values:
- Ub = 450 V
- Ik = 45...50 mA
- Ra-a = 6k6
- Pout = 30...35 W
- THD = low.
I have used these with UL-mode (PP) with the following values:
- Ub = 450 V
- Ik = 45...50 mA
- Ra-a = 6k6
- Pout = 30...35 W
- THD = low.
Nice... I used 400V, 70ma, Ra-a 8k, Tetrode with regulated screen at 325V (Yes I know that exceeds the ratings, but they work for years in this config) before I abandoned them for sweep tubes in triode connection 🙂 I also preferred the 6P3S over the 6P3S-E 🙂 YMMV
I boosted a 6922 dual triode to 30w using Transistors in p-p config. 12AX7 provides enough gain to get full power from 500 mV input.
Last edited:
Bias voltage will vary from tube to tube. If you're not using cathode bias, you need to adjust the bias voltage while checking the current. For what it's worth, I've built amps with 6P3S in triode and in regulated tetrode. The "typical" datasheet implementation for class A push pull will give you 15W and still have quite low distortion.
Thanks for this. One day I'll learn how to use SPICE instead of just building and testing the circuit. Can you adjust that SIM for 400V? Does it make closer to 10W?
Be careful of what tube you use: voltages, currents, and dissipations you run them at.
Maximum plate dissipation and Max screen voltage are not all the same for those tubes.
Pentode/Tetrode operation with screen voltage less than plate voltage is one thing.
Triode wired operation is another.
artosalo's suggested operating point: 400V x 58mA = 23.2 Watts
6L6 metal, 6L6G, 6L6GA 19 Watts plate screen 270V
6L6GB 19 or 22 Watts plate (depending on manufacturer) screen 270V
6L6GC 30 Watts plate screen 450V (these have the most capability)
6P3S and 6P3S-E . . . check the data sheets before deciding on the voltages and currents you run them at.
Maximum plate dissipation and Max screen voltage are not all the same for those tubes.
Pentode/Tetrode operation with screen voltage less than plate voltage is one thing.
Triode wired operation is another.
artosalo's suggested operating point: 400V x 58mA = 23.2 Watts
6L6 metal, 6L6G, 6L6GA 19 Watts plate screen 270V
6L6GB 19 or 22 Watts plate (depending on manufacturer) screen 270V
6L6GC 30 Watts plate screen 450V (these have the most capability)
6P3S and 6P3S-E . . . check the data sheets before deciding on the voltages and currents you run them at.
As I said, 6P3S work for years at that level. 20W Plate + 2.75W screen = 22.75W... 23.2W is not a large stretch from there. Obviously, if you run them at a lower Pd they will last longer. Agreed though, some specs should be respected... Some can be flaunted. To be honest, the only tubes I've have screen failure have been Chinese 6550 or KT88.
Last edited:
kodabmx,
Good point.
Lots of tubes will run at higher levels than they are rated for.
How about some guitar amplifiers; and they are driven very hard.
Music:
Pentode/Tetrode with screens at lower voltages works well because the plate does not go below the screen voltage for very long, and only at loud passages.
Triode wired, the plates never go below the screen voltage, no matter the signal level.
Ultra Linear, potentially the most abusive mode.
The screen voltage starts higher than the plate voltage (OPT DCR voltage drop).
The screen voltage only falls at 40% of the plate falling rate.
The plate voltage goes far below the screen voltage really fast.
Ugh!
Good point.
Lots of tubes will run at higher levels than they are rated for.
How about some guitar amplifiers; and they are driven very hard.
Music:
Pentode/Tetrode with screens at lower voltages works well because the plate does not go below the screen voltage for very long, and only at loud passages.
Triode wired, the plates never go below the screen voltage, no matter the signal level.
Ultra Linear, potentially the most abusive mode.
The screen voltage starts higher than the plate voltage (OPT DCR voltage drop).
The screen voltage only falls at 40% of the plate falling rate.
The plate voltage goes far below the screen voltage really fast.
Ugh!
Very true. Never really though about it like that, but worst case UL mode will be 0V plate, 40% B+ on the screens (not that this is realistic, but you get the idea).
