Now a word to my fellow blind tube techies. This diagram includes the part that was in the first lesson. Each lesson will add a little to the existing diagram. By the time we get to the end of this series it could get pretty repetitive. Below each schematic there will be two links. One will be just the parts added in the current lesson. The second link will be the complete diagram. You can take your choice.

One side of the line plug connects to chassis ground. This point will be referred to as ground. The other side of the line plug connects to the off/on switch which is part of the volume control. The other side of the switch connects to one side of the 35 volt heater of the rectifier tube and one side of the dial light. The other side of the dial light connects to the tap on the heater. This point connects to the plate of the rectifier tube. The plate is bypassed to ground by a .005 mike cap. The other side of the heater goes to one side of the 50 volt heater of the audio output tube. The other side of this heater goes to one side of the 12 volt heater of the detector and first audio. The other side of this heater goes to the heater of the I F tube. The other side of this heater goes to the heater of the converter tube. The other side of the converter tube heater goes to ground. The heaters form a series circuit. The cathode of the rectifier tube goes to the positive side of a 40 mike 150 v cap. This point is labeled high current B plus. This point goes through a 1 k ohm 1 watt res to the plus side of another 40 mike 150 v cap. This point is labeled low current B plus. The negative side of both caps is grounded. Both of these caps are usually in one unit called a dual cap.

The converter. On the left is a tuned loop antenna. It is an inductor which has been wound big so it can pick up the magnetic field of the radio waves. The top of the antenna goes to grid 3 of the converter tube. The top of the antenna also goes through one section of the tuning cap to ground. The bottom end of the antenna goes to a point labeled AGC. This point goes through a .1 mike cap to ground. The cathode of the converter tube goes to the tap on the oscillator coil. The bottom of the coil is grounded and the top goes through a 220 pf cap to grid 1 of the converter. Grid 1 also goes through a 22 k ohm res to ground. The coil is tuned by the other section of the tuning cap. Grids 2 and 4 of the converter tube are connected together inside the tube and are brought out to a single pin. This pin connects through a .01 mike cap to ground. This pin also goes through a 1 k ohm res to low current B plus. This same pin also connects to the low end of the primary of the first i f can. The high side connects to the plate. In the octal tube grid 5 is brought out to a separate pin and this pin is grounded. In 7 pin mini tubes grid 5 connects to the cathode inside the tube. The high end of the i f secondary connects to the control grid of the i f amplifier tube. That's all for this lesson. End verbal description.
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