Schematic diagram of Philco radio. The antenna, an external wire, connects to the top of the primary of the antenna coil. The bottom connects to the radio ground and can optionally be connected to earth ground. There is a 20 k ohm res in parallel with the primary winding. A 25 pf cap connects from the antenna terminal to a tap on the secondary of the antenna coil. The secondary is tuned by one section of the two section variable cap. The top of the secondary goes to grid 4, top cap, of the 1D7 tube. The bottom of the coil goes through a .05 mike cap to ground. The bottom of the coil also goes to the AGC line. One side of the filament of the 1D7, pin 2, goes to ground and the other side, pin 7, goes to a point labeled F, minus 2 volts. Grid 1 connects to the top of the oscillator coil. The coil is tuned by the other section of the variable cap. The bottom of the coil goes through a 51 k ohm res to ground. The tap goes through a trimmer cap to ground. The bottom of the oscillator coil goes through a .001 mike cap to grid 2, pin 6 of the 1D7. Pin 6 also goes through a 10 k ohm res to B plus 1, 130 volts. Grids 3 and 5 are tied together inside the tube and come out to pin 4. Pin 4 goes to B plus 2, 90 v. The plate goes to one side of the primary of the I F transformer. The other side goes to B plus 1. The top of the secondary goes to grid 1, top cap of the 1D5. The bottom of the secondary goes to the AGC line. The filament connects between ground and F. The F side of the filament is internally connected to grid 3. Grid 2, pin 4, connects to B plus 2. The plate, pin 3, connects to the bottom of the primary of the other I F transformer. The top goes to B plus 1. The bottom of the secondary goes to pin 4, one of the diode plates, of the 1H6. The top of the secondary goes through a 110 pf cap to ground. This point also goes through a 51 k ohm res to the top of the volume control 500 k ohm. The top of the control also goes through a 110 pf cap to ground. The wiper of the control goes through another 110 pf cap to ground. The wiper also goes through a .015 mike cap to the triode grid, pin 6, of the 1H6. The grid goes through a 1 meg res to C minus 2, AGC bias. A 110 pf cap connects from pin 4, diode plate, to pin 5, other diode plate. Pin 5 also connects through a 1 meg res to C minus 2. Pin 5 also connects through another 1 meg res to the AGC line. The filament of the 1H6 connects between ground and F. The triode plate, pin 3 goes through a 470 k ohm res to B plus 1. The plate goes through a 110 pf cap to ground. It also goes through a .05 mike cap to pin 4, grid 1 A of the 1E7 twin pentode output tube. Pin 4 goes through a 1 meg then a 160 k ohm res to C minus 1, the output bias line. The junction of the 1 meg and 160 k goes to the grid, pin 5 of the 1H4 phase inverter. The plate, pin 3, goes through a 470 k ohm res to B plus 1. The plate goes through a .05 mike cap to pin 5, grid 1 B of the 1E7. Pin 5 also goes through a 1 meg res to C minus 1. Pin 8, the screen grid of both sections of the 1E7 goes to B plus 1 and through a .15 mike cap to ground. The suppressor grid is internally connected to one side of the filament. This goes to pin 7 and connects to the point F. The other side of the filament goes to ground. Each of the two plates, pins 3 and 6 goes through a .004 mike cap to ground. Each plate goes to one side of the high impedance speaker voice coil. The center tap of the voice coil goes to B plus 1. Pin 1 of the power plug goes through the on/off switch to ground. Pin 2 is not used. Pin 3 goes through an 8 k ohm res to B plus 2. This point goes through a 3 mike cap to ground. Pin 4 goes to C minus 2, AGC bias. Pin 5 goes to C minus 1, output bias. Pin 6 goes to B plus 1. Pin 7 goes to point F. pin 8 goes to ground. End verbal description.
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