[Ron Ramirez]

I have a pretty clean Philco 70 chassis, to which I plan to add Ed Locker's AVC modification.

This has been previously discussed starting here.

The purpose of this mod is to not only add automatic volume control (AVC) to a radio which was designed without AVC, but also to eliminate the distortion which is inevitable in radios which use the "plate detector" circuit.

With this mod, the plate detector will become a tetrode audio amplifier, and a germanium diode will be added to perform the second detector function.

I've taken the liberty of redrawing Ed's schematic below (NOTE: Two errors were found in the schematic previously posted here, and have now been corrected below):

[Image: https://philcoradio.com/images/phorum/70mod/70_mod.jpg]

Hint: Right-click the image above and click View Image to see a full resolution version of this schematic. Then right-click that image and click Save Image As to save it to your computer.

I'm looking forward to performing this mod. Both Ed Locker and Rob Feenstra report excellent results from doing this mod to their radios.