[Ron Ramirez]

In the case of this model (the later 4-band 16), KCMike is correct.

It is my belief that Philco decided they needed a switch to fill a hole in already-produced 16 cabinets when they introduced the 4-band 16 in late 1934 (after the 1935 season had begun), so they stuck an SPST toggle switch in the bass compensation section of the volume control circuit. I can't prove it because there is no supporting (or refuting) evidence that I know of, but it is a logical assumption.

The 4-band 16 does not have the QAVC (squelch or "Quiet Automatic Volume Control") that the 5-band 16 had...but it does add an RF amp, which is better than having QAVC.

Study a 4-band 16 schematic to learn more and see how the switch is placed in the circuit.