peacocksuit,
As was posted earlier in this thread . . .
Many DMMs load down a grid that has its 1.3 Meg Ohm grid resistor that returns to the cathode's self bias resistor, that is an expected reading.
Instead read the cathode voltage, as I said earlier it should be about 20% to 40% of the cathodyne's B+ voltage at the top of the plate load.
Any voltage that is out of this range is either caused by a bad tube, or bad resistor, or bad design parts values.
A measurement of the grid voltage that is done with a special high resistance meter (like 100 Meg Ohms), would make the measurement more accurate, like within about 2% of the actual value.
But, if the cathode voltage is correct, then for an ECC82 or 12AU7, the grid voltage will be approximately 3 to 8 volts more negative than the cathode voltage (the cathodyne current is perhaps 2 to 4mA, and the cathode to plate voltage is perhaps 60 to 120V).
The unloaded grid voltage (unloaded by a DMM) will certainly be much larger than 16V.
Keep plugging away.
As was posted earlier in this thread . . .
Many DMMs load down a grid that has its 1.3 Meg Ohm grid resistor that returns to the cathode's self bias resistor, that is an expected reading.
Instead read the cathode voltage, as I said earlier it should be about 20% to 40% of the cathodyne's B+ voltage at the top of the plate load.
Any voltage that is out of this range is either caused by a bad tube, or bad resistor, or bad design parts values.
A measurement of the grid voltage that is done with a special high resistance meter (like 100 Meg Ohms), would make the measurement more accurate, like within about 2% of the actual value.
But, if the cathode voltage is correct, then for an ECC82 or 12AU7, the grid voltage will be approximately 3 to 8 volts more negative than the cathode voltage (the cathodyne current is perhaps 2 to 4mA, and the cathode to plate voltage is perhaps 60 to 120V).
The unloaded grid voltage (unloaded by a DMM) will certainly be much larger than 16V.
Keep plugging away.
