AC goes into the 35Z5 rectifier on the plate (after going through the dial lamp and part of the 35Z5 filament). The DC starts at the cathode of the 35Z5, which is pin 8. From there it goes through a 33 ohm resistor to the first filter cap (40 uF). From that point, there is a B+ feed to the output transformer. Note that this is a tapped output transformer. The bottom part of the primary coil is a "hum canceling" winding, and the B+ feed to the rest of the radio goes out the bottom terminal of the output transformer through a 1200 ohm resistor to the second filter cap (also 40 uF). From this point, all the rest of the radio gets its B+.
Schematic available here: http://www.radiomuseum.org/r/sonora_rad_rdu209.html