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:

I think you mean the transformer is 25 volts center-tapped, or 12.5-0-12.5 volts.
Don

It draws .3 amps? The 6y6,http://www.radiomuseum.org/tubes/tube_6y6.html.

I don't think filament current gets returned through the dial lamps. I believe the reason they did this was to save money on the wire size of the copper and the resulting smaller overall size of the transformer, itself.



Dave

Dave, That's a nice clear drawing.
Don

I would be more interested in the use of two 6U7-Gs , as 1st and 2nd IF, without an extra
IF transformer, using resistance coupling.


Also, I think I have a bunch of new 6U7-Gs *somewhere*.

Yeah I saw that about the two IF stages. I guess they just wanted some more gain, cheaply...