Phase inverter

[rsumperl]

Good morning everyone,
I'd like to consider a Long Tail phase inverter based on a 6M11 compactron. Given the specs on the 6M11 and the circuit diagram I found, how practical could this be? With 225v instead of 300v, do you think I can get sufficient swing? Will I need to add an additional driver circuit?

Thanks,
Ray

[Shannon Parks]

Those twin triodes will kind of be like 6DJ8s or closer to 5965. Should work fine. Bias your CCS at 6mA (3mA each triode) and use 33K plate resistors. I would just connect the second grid to ground with a 470 ohm resistor. Use another 470 ohm resistor on the first grid as a grid stopper. Else all will work fine. I simulated +/-50VAC swing, so it'll be plenty for most amps. Just let the pentode pins float (NC).

Shannon

[rsumperl]

Thank you for the inputs. Quick question, I've seen several LTP phase inverter designs built with Pentodes. Is there any advantage or disadvantage using a Pentode?

Thanks,
Ray

[Shannon Parks]

I presume that those designs are using a pentode as a CCS in the tail. While doable, the current trend is using a LM334Z (see my Poseidon & ST70 circuit) when AC-coupled, or a IXYS 10M45S or Supertex DN2540 when DC-coupled.

Shannon