[Ron Ramirez]

1935 season - Hex or "acorn" style on most Philco models, except for Model 16, late version 144, and 97 with concentric tuning knobs; these used knobs with a sort of octagonal shape. I've seen these in black, and very dark brown.

1936 season - New knobs except for the cheaper models; all black.

1937 through 1940 seasons - Same style round knobs as most 1936 models, except they are brown instead of black. The band switch knobs on 1937 and 1938 models are VERY different from the bar knob used on some 1936 models only.

1941 season - A new knob made of Tenite, smaller than previous (1937-40) knobs.