12AX7/ECC83



  [Schematic of phase inverter circuit omitted from text file.]


          Supply Voltage                     250           350 volts
          Plate Voltage                       65            90 volts
          Total Current                      1.0           1.2 mA
          Cathode Resistance              68,000        82,000 ohms
          Plate Load Resistance (Rp)         0.1          0.15 megohm
          Plate Load Resistance (Rp')        0.1          0.15 megohm
          Output Voltage[6] (RMS)               20            35 volts
          Voltage Gain                        25            27
          Percent Distortion[7]                1.8           1.8 %


  [Diagram of tube envelope and basing omitted from text file.]


[6] Eo at grid current starting point.
[7] The total harmonic distortlon is approximately proportional to the 
output voltage