hallo,

a friend of me asked me to bias his tube guitar amplifier. after some research on the net i found out that the circuit is a fixed bias circuit.
so by regulating the negative grid voltage i can regulate the anode current.
now for knowing the max dissipation you have the formula, P= anode current*anode voltage
i can measure the anode voltage but to know the anode current, i placed a resistor from cathode to ground and measured voltage across this resistor.
by applying ohms law i can approximately calculate the current.

now my question; can i leave the resistor of 1k at the cathode?

 

No.
If you left it in, when the tube started conducting, the resistor on the cathode would act as the load.

 

Hi

Go to the forums at www.hoffmanamps.com , best resource I know for tune stuff.

Andrew

 

Voltage dropped through one (1) ohm resistor or (2.2 ohm) can be measured to adjust bias voltage. Higher value of resistor will tolerate the working point of the tube.