Figure 9.11 Full schematic of 3 way portable.
One end of the loop antenna is connected to a point we will call AGC. The other end of the loop connects to one section of the main tuning capacitor. The other side of all sections of the capacitor are connected to AGC. The AGC point is bypassed to radio common through a 0.05 u f capacitor. AGC goes through a 2.2 meg ohm resistor to the top of the volume control. There is a trimmer capacitor connected across the loop. The top end of the loop goes through a 100 p f capacitor to the control grid of the RF amplifier, 1U4. The grid also goes through a 3.3 Meg ohm resistor to a point we will call RF AGC. This point is bypassed to the negative side of the filament by a 0.01 u f capacitor. The point RF AGC is at the junction of two resistors. One of them is a 2.2 Meg ohm and goes to the negative side of the filament. The other resistor is a 5.6 meg ohm and goes to the top of the volume control. The suppressor grid is tied to the negative side of the filament inside the tube. The plate connects through a 1 k ohm resistor to the top of the primary of the RF transformer. The other end of the primary connects to the screen grid. The screen grid and RF primary connect to B plus. Detailed connections of the filaments of all tubes will be given in Figure 9.12. The bottom end of the secondary of the RF transformer is connected to AGC. The top of the secondary connects to the second section of the main tuning capacitor. There is a trimmer capacitor in parallel with the section of the tuning capacitor. There is a tap on the secondary which connects to one end of a 330 ohm resistor. The other end of this resistor goes to the signal grid, grid 3, of the converter tube 1R5. To get this out of the way now, grid 5 connects to the negative side of the filament, and grids 2 and 4 are connected together. Both of these connections are inside the tube. The oscillator grid, grid 1, connects through a 100 k ohm resistor to the negative side of the filament. This grid also connects to one end of something that looks like a coil but the other end is not connected to anything. As explained in the text this forms a capacitor which couples signal from the primary of the oscillator coil to the grid of the tube. The bottom of the oscillator coil primary goes to AGC. The top goes to the third section of the main tuning capacitor. There is a trimmer capacitor across this section of the tuning capacitor. The top of the secondary of the oscillator coil goes to grids 2 and 4 of the converter tube. The bottom of the secondary is bypassed to radio common through a 100 p f capacitor. The bottom also goes through a 33 k ohm resistor to B plus. The plate of the converter tube goes to the top of the primary of the first IF transformer. The bottom goes to B plus. The top of the secondary goes to the control grid, grid 1, of the IF amplifier, 1U4. The bottom of the secondary goes to the negative side of the filament through the parallel combination of a 0.001 u f capacitor and an 8.2 k ohm resistor. Grid 3 connects to the negative side of the filament. The plate connects to the top of the primary of the second IF transformer. The bottom connects to grid 2, screen grid. There is a 1 meg ohm resistor in parallel with the primary. The bottom of the primary and grid 2 connect to B plus. The top of the secondary connects to the plate of the diode in the detector and first audio tube 1U5. The bottom connects through a 220 p f capacitor to the positive side of the filament. The bottom end connects to the AGC point is described earlier. The bottom also connects to the top of the volume control. The wiper of the control connects through a 0.002 u f capacitor to grid 1 of the 1U5. The grid also goes through a 10 meg ohm resistor to the positive side of the filament. The bottom of the volume control goes to the positive side of the filament. The screen grid is bypassed to the positive side of the filament through a 0.01 u f capacitor. The screen grid also goes through a 3.3 meg ohm resistor to B plus. Grid 3 is connected to the negative side of the filament. The pentode plate goes through a 1 meg ohm resistor to B plus. The plate also goes through a 0.005 u f capacitor to grid 1 of the audio output tube, 3V4. The grid also goes through a 3.3 meg ohm resistor to the positive side of the 1U5 filament. Grid 3 is connected to the center tap of the 3V4 filament. The plate of the 3V4 connects to the top of the primary of the output transformer. There is a 0.005 u f capacitor connected between the plate and negative side of the filament. The bottom of the primary goes to the screen grid and B plus. The secondary connects to the speaker. One side of the circuit is connected to chassis ground.

The on/off switch on the volume control is a two pole single throw switch. The line/battery switch is a 3 pole double throw. I will describe this switch twice, first in the line position and again in the battery position.

l/b switch in line position. The lower prong of the line plug goes to the line side of gang 3 of the l/b switch. The swinger of the switch goes to one side of one pole of the on/off switch. The other side of the o/o switch goes to radio common. The top prong of the line plug goes through a 0.05 u f capacitor to radio common. This prong also connects to the anode of the selenium rectifier. The cathode of the rectifier goes to one end of a 150 ohm resistor. (Note: When, not if but when you replace the selenium rectifier with a silicon diode you will need to increase the value of this resistor. I can't say by how much, but voltages are given in figure 9.12. All you need to do is match up the voltages in your radio with those on the diagram.) The other end of the resistor you need to change, goes to the positive end of a 40 u f 150 v capacitor. This point goes through a 1 k ohm resistor to the plus end of a 20 u f 150 V capacitor. This point goes through a 1 k ohm resistor to the line terminal on gang 2 of the l/b switch. The swinger of this switch goes to the positive side of the 3V4 filament. The negative ends of all the 150 volt capacitors are connected to radio common. The junction of the 1 k ohm resistor and 40 u f capacitor connects through an 820 ohm resistor to the line side of the l/b SW gang 1. The swinger of gang 1 connects to the plus side of a 40 u f 150 volt capacitor. The swinger also connects to B plus.

l/b switch in battery position. The negative sides of the A and B batteries are connected together. And go to the battery side of gang 3 of the l/b switch. The swinger of gang 3 goes through one pole of the on/off switch to radio ground. The positive of the A battery goes to the battery side of gang 2 of the l/b sw. The swinger of gang 2 goes to the positive side of the 3v4 filament. The positive side of the B battery goes to the battery side of gang 1 of the l/b sw. the swinger of gang 1 goes to the 40 u f capacitor and to B plus.

End verbal description.
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