Secondary Emission on the 6CL6 Tube

The 6CL6 also produces a nice secondary emission plot. The 6CL6 is a pentode, meaning there are 3 screens between the cathode and plate. It is designed for video applications in television sets. (RCA)

6cl6 base diagram  This is a diagram of the 6CL6 tube.

In order to produce the secondary emission effect, just as in the 6AU6 I had to connect the screen grid and suppressor grid in order to run the tube as a tetrode. As a pentode, with grid 3 grounded, secondary emission is eliminated just as before in the 6AU6. With the tube connected as a tetrode, I applied 80 volts across the screen, the typical 6.3 volts to the heater and up to 150 volts potential across the plate. These conditions in the 6CL6 tube produced a secondary emission effect at a plate potential of around 10 volts up to a plate potential of around 50 volts. At a plate potential of 84 volts, the 6AU6 displays secondary emission effects between plate potentials of 10 volts to 80 volts. The two tubes are then similar, but still have small differences in their physical properties that make their behavior slightly different. I did not try to observe secondary emission on the 6CL6 at higher plate potentials, but it would behave similarly to the 6AU6.

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Secondary emission on the 6AU6 tube

Secondary emission on the 6146 tube

Secondary emission on the 5763 tube

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