Wyan001:
Unfortunately you can't make adapter to add R to cathode bias: heater pins should be connected directly to 5v heater supply and virtual center of the heater goes via bias resistor to the ground (that's where additional R supposed to go). Also cathode resistor (in this case exiting one in series with the 200 ohm) is bypassed by capacitor.
Unfortunately you can't make adapter to add R to cathode bias: heater pins should be connected directly to 5v heater supply and virtual center of the heater goes via bias resistor to the ground (that's where additional R supposed to go). Also cathode resistor (in this case exiting one in series with the 200 ohm) is bypassed by capacitor.