[jrblasde]

I’ve consulted a couple of the books which I got from Jim Koehler, Elements of Radio Servicing (Marcus and Levy, 1947) and Elements of Radio, Second Edition (Marcus and Horton, 1948). It looks to me that my Philco 46-480 has the AVC bus connected to the screen grid, the output of the preceding IF transformer connecting to the control grid, and the suppressor grid grounded. It seems a close design to this textbook example of a 1st IF section, except that this example only connects the screen grid to a fixed 100V rather than to an AVC bus.

   

   

And, just as I discovered and corrected on my own schematic, the control and suppressor grids are no connected together.

[morzh]

Wasn't that the Suppressor grid that we were talking about, that got connected with the AVC?
Anywho, the initial question was, could the Control Grid be connected to Suppressor Grid?
To me the answer is, no it shouldn't.

[jrblasde]

I agree, the two should not be connected. Due to poor image quality of the original Philco schematic, it was unclear if the design intended to connect the two. Had I thought about it more deeply, I would have realized that they shouldn’t be connected. But, at the time, I suppose I was more focused on trying to interpret the original schematic so that I could reproduce it.

[jrblasde]

It’s here! Mark Oppat is getting a special mention for this restoration!