12AT7/ECC81

                MAXIMUM RATINGS (Each Section)

                    Design Center Values

Zero Signal Plate Voltage                  550 volts
Plate Voltage                              300 volts
Plate Dissipation                          2.5 watts
Cathode Current                             15 mA
Grid Voltage                               -50 volts
Grid Voltage (Grid Current = + 0.3 uA)    -1.3 volts .
Grid Resistance[4]                           1 megohm
Heater to Cathode Voltage                   90 volts
Heater to Cathode Resistance            20,000 ohms




                  Typical Operating Conditions

                 Class A Amplifier (Each Section)

Plate Voltage        100      170      200     250  volts
Grid Voltage       - 1.0     -1.0    - 1.0    -2.0  volts
Plate Current        3.0      8.5     11.5    10.0  mA
Transconductance    3750     5900     6700    5500  umhos
Amplification Factor  62       66       70      60
Plate Resistance    16.5     11.0     10.5    11.0  K ohms


[4] with self bias



 [diagram of base and envelope omitted from text file]