shutterdialradio posted about his Silvertone 15-61 over in E/M (viewtopic.php?f=6&t=192749
The radio he's using has a very interesting tube line-up: 6K8G 6U7G 6U7G 6Q7G 25C6G 5Y3G. The heater winding on the transformer is a center-tapped arrangement, with two dial lamps in series going from one side to ground.
Near as I can tell, those lamps are dropping 12.6V. Then, two 6.3V filaments are put in series on each side of the transformer, and return through the dial lamps.
Can anyone think of a reason they wired it this way? They could've used a 6Y6 for the output, and that would've been that - no series/parallel filament wiring required. Did this save money, somehow? Maybe Sears was sensitive enough to the cost of an extra inch of wire?
Schematic for reference: