[Radioroslyn]

Here's a drawing of the p/s that's a little easier to follow. Perhaps it's just a matter of semantics. I'm calling it b- because it isn't grounded to the chassis (the exterior of the filter can). You are calling ground because unless it's insulated from the chassis it would be grounded.

Not trying to pick a fight or anything but the chassis ground point is found thru #47. It's used to develop the negative voltage applied to the control grids of the 75 tube (-3vdc) and the 42 tube (-21vdc). Without these negative voltages these tube would draw excessive current and generally would be hating life.  Over heating the power transformer and stuff like that.

Voltages listed are off the top of my head not to be used as an exact measurement. Oh and btw some Philco sets one of the filters is at chassis ground and the other is at b-. Some have the b- floating just like your set but there is a filter cap from chassis ground + to the hv ct - to filter the - side of the dc output... Check out #75 on this one https://philcoradio.com/library/download...%20165.pdf Better yet get you one. The 16/116 tombstone is the one to have.