08-11-2022, 01:41 PM
Well I have had a bit of time and more importantly the inclination to patch the circuit around the EL91 together.
I have tried replacing the anode transformer with a resistor, used two values one of 220 Ohm and one of 2K2 Ohm. Nether made much difference to the values with the cathode at around 40 Volts, the junction of the three resistors being at 27.5 volts and the grid a bit lower at 26 Volts, all measured with my DVM. The two different values made little difference to the 10+mA through the cathode resistors.
I guess the issue is mute as I need to drive the output stage in another way so thinking of using a Phase Inverter
using a CV4031/ECC91.
Adrian
I have tried replacing the anode transformer with a resistor, used two values one of 220 Ohm and one of 2K2 Ohm. Nether made much difference to the values with the cathode at around 40 Volts, the junction of the three resistors being at 27.5 volts and the grid a bit lower at 26 Volts, all measured with my DVM. The two different values made little difference to the 10+mA through the cathode resistors.
I guess the issue is mute as I need to drive the output stage in another way so thinking of using a Phase Inverter
using a CV4031/ECC91.
Adrian
Learning as I go!
Youtube EF91 Valve
Youtube EF91 Valve
