Hi, I dont understand the issue with the two 100r. It should only reference the virtual CT for the heaters to a positive voltage. You had different bias voltage on pin 8 of the power tubes with them?
Looking back over the results with the 2 x 100r resistors in place, I got the following measurements; Voltage drop across cathode resistor = 7.2 volts, so divided by the 42 ohms of the measured resistor is 0.1714mA which is halved as it's serving two valves, so 0.086mA. The average cathode to plate voltage here was 243v, so multiplied together gives 20.8watts at idle, well over the 14 watt max for a 6V6GT (150% ish).
Hi, I dont understand the issue with the two 100r. It should only reference the virtual CT for the heaters to a positive voltage. You had different bias voltage on pin 8 of the power tubes with them?
With the 2 x 100r resistors in place the cathode resistor measures only 42 ohms, giving a significant increase in the bias current.
Looking back over the results with the 2 x 100r resistors in place, I got the following measurements;
Voltage drop across cathode resistor = 7.2 volts, so divided by the 42 ohms of the measured resistor is 0.1714mA which is halved as it's serving two valves, so 0.086mA. The average cathode to plate voltage here was 243v, so multiplied together gives 20.8watts at idle, well over the 14 watt max for a 6V6GT (150% ish).