In principle, the circuit functions in the same manner as the circuit of 3a with the advantage that the neutralizing capacitor does not have the B voltage across it. The primary and secondary windings of the RF transformer must be properly polarized to allow neutralization to take place. Additionally, the primary was frequently inter wound with the ground end portion of the secondary coil to obtain tight coupling. Figures 3c and 3d show two other neutralizing circuits employed in receivers of the 1920's. In Figure 3c, L is part of the tuned circuit at the next stage grid but is oriented for minimum coupling to the other windings.
L is wound on a separate form and is mounted at right angles to the coupled windings.
If the windings are properly polarized, the voltage across L due to the circulating current in the grid circuit will have the proper phase to cancel the signal coupled through the grid to plate capacitance. Again, balance is achieved by adjustment of Cn. The Rice circuit of Figure 3d uses a center tapped coil in the grid circuit. With this arrangement the signal voltages at the ends of the tuned grid coil are equal and out of phase. Cn is then adjusted to equal the grid to plate capacitance of the tube to effect complete neutralization.