01-25-2022, 08:27 PM
On the 75 and the 42 tubes the cathodes are connected to the chassis ground. If you measure from the cathode or the chassis it will be the same. Unless you have a bad rivet.
The control grids are using whats called fixed bias which is developed across #47.
The 6A7 and 78 use cathode bias using the voltage developed across #'s 8 & 9. In this case the cathode is not grounded and the bias voltage is not coming directly from the power supply.
The control grids are using whats called fixed bias which is developed across #47.
The 6A7 and 78 use cathode bias using the voltage developed across #'s 8 & 9. In this case the cathode is not grounded and the bias voltage is not coming directly from the power supply.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
