Grounding heater CT on the Cathode.

[tribi9]

For a cathode biased amp.... Please correct me if im wrong. To ground the heater CT on the cathode I need to actually connect the CT wire on the pin on the power tube and not on the Cathode ground, correct? If so, is a resistor necessary?

Cheers

[martin manning]

Yes, the filament CT (or junction of the two resistors used to form an artificial CT) is connected to the top of the power stage's cathode resistor instead of connecting it to ground. The idea is to elevate the filament string to the level of the DC bias voltage.

[tribi9]

Once again, thank you Martin.

[tubeswell]

But when you connect the CT to a cathode-biased output tube socket's cathode pin, you don't need to add another resistor - just hook the CT straight up to the pin.

[tribi9]

Thank you Tubeswell, i figured you wouldn't have to use a resistor as it would throw the bias off.