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Bias Calculator

Bias Settings For Safe Plate Dissipation
Class AB: 70%    Class A: 90%

Class   
Tube Type    
Plate Voltage    
     mA

 


CALCULATE PLATE DISSIPATION
Based on Plate Voltage and Cathode Current Readings

In these calculations, 5% of the cathode current is assumed to be screen current. This calculator is for a single tube.


Plate voltage
DC voltage measured between plate and cathode. (Actual Plate Voltage)
Example:
Octal - pins 3 and 8
9 pin - pins 7 and 3

Cathode Current (milliamps)
Displays Approximate Plate Current After Calculation

Plate Dissipation (Watts)


Note: For calculating plate dissipation in cathode biased circuits, subtract the measured cathode voltage from the measured plate voltage and use that as the plate voltage in the calculator above.



CALCULATE PLATE DISSIPATION (In Cathode Biased Output Stage)
Based on Voltage and Resistance Readings

In these calculations, 5% of the cathode current is assumed to be screen current. With multiple tubes sharing the same cathode resistor, this calculator assumes the tubes are fairly well matched.


How many tubes share the same cathode resistor? (typically 1 to 4)

Voltage measured across cathode resistor

Actual resistance of cathode resistor

DC voltage measured between plate and cathode. (Actual Plate Voltage)
Example:
Octal - pins 3 and 8
9 pin - pins 7 and 3

Plate dissipation per tube (Watts)

Approximate plate current in each tube (in milliamps)





Will calculate and display plate power dissipation and approximate plate current per tube.