09-11-2020, 10:13 PM
There is a reason why 21,21A, and 21B are wired as per the schematic.
21A and B filter the both the B- and B+ outputs of the power supply. If those are connected to the chassis and the bias resistor it will short out any negative voltages used to grid bias the 1st audio stage and the output stage. Means excessive plate current and distortion.If you just connect them to the chassis w/o connecting them to the bias resistor then they won't filter out the 60cy hum in the - side of the power supply. Means hum. 21 is used for decoupling any audio signals that maybe modulating the B+. It's only connected across the + side of the hv.
21A and B filter the both the B- and B+ outputs of the power supply. If those are connected to the chassis and the bias resistor it will short out any negative voltages used to grid bias the 1st audio stage and the output stage. Means excessive plate current and distortion.If you just connect them to the chassis w/o connecting them to the bias resistor then they won't filter out the 60cy hum in the - side of the power supply. Means hum. 21 is used for decoupling any audio signals that maybe modulating the B+. It's only connected across the + side of the hv.
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
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
