Figure 4B.18. Parts eh and B of this figure are almost identical. The identical parts will be described first. The cathode of the tube goes to ground through an RF choke. The grid of the tube goes through a capacitor, C3, to the cathode. There is another capacitor, C4, from the cathode to ground. There is a resistor, R1, from the grid to ground. One end of a capacitor, C2, connects to the grid. The other end connects to the tuned circuit which will be described below. The plate of the tube goes to B plus.
In part eh one end of the coil, L1, connects to the capacitor from the grid. The other end of the coil goes to ground. There is a variable capacitor, C1, in parallel with the coil.
In part B one end of the coil, L1, connects to the capacitor from the grid. The other end of L1 connects to the variable capacitor, C1. The other end of C1 goes to ground.
End of verbal description.