Wayne Parham Messages: 18778 Registered: January 2001
Illuminati (33rd Degree)
Both schematics - the one for the Gamble-Skogmo Model 43-6927 and the Model 43-7603 - show a fixed magnet speaker in them.
However, the chassis was designed like most other tube radios, with a tube rectifier and a "pi filter", having a capacitor in shunt across the rectifier output, followed by a series inductor (the field coil) followed by another shunt capacitor.
In the case of the 43-6927 and 43-7603 radios, the field coil is replaced with a 1.8kΩ, 20 watt resistor (connected to pin 8 of the 6X5 tube). That way, a fixed magnet speaker can be used. But if you have a field coil speaker, you can take that resistor out and put the field coil winding in its place.