[Ron Ramirez]

Philco did not start using decals to identify the various knobs until the 1939 season. The exceptions to this are the high end 1937 and 1938 models: 37-690, 37-675, 37-116, 37-9, 37-10, 37-11; 38-690, 38-116, 38-1, 38-2, 38-3. Even these did not have a decal identifying the band switch.

How would you know? The original owners knew because they had the owner's manual. Those owner's manuals were usually tossed out by those same original owners, and few remain.

So how can you know now? Just ask someone here...

The upper middle knob is, obviously, the tuning knob.

Lower three knobs, left to right: Off-On-Tone, Band Switch, Volume. The off-on-tone control is a multi-position switch instead of a variable control; this is how Philco designed the 37-640 and many other 1937 Philco models.

Band switch: Extreme counterclockwise - Standard Broadcast (AM); second position clockwise - Shortwave (lower band, the scale of which is just above the AM band on your dial); third position clockwise - Shortwave (upper band on your dial).