Secondary Emission on the 5763 Tube

The 5763 tube is a beam power pentode. The heater is again typically run at 6.3 volts. (Bill)

{short description of image}  This is a diagram of the 5763 tube.

With the suppressor grid hooked to the screen grid, the tube operates like we would expect, similar to the 6AU6 and the 6CL6 as discussed before. I used a 5.8 volt bias, 92 volt potential across the screen and up to 90 volts potential across plate. These conditions produced a rather pronounced secondary emission. The effect begins to appear at a potential across the plate of around 10 volts, and then disappears at a plate potential of around 60 volts. Interestingly, in this tube I was not able to turn the secondary emission effect off. Grounding the third grid only succeeds in reducing the effect, not eliminating it. That means that the tube produces secondary emission even during normal operation as a pentode. The effect begins when the plate potential reaches about 5 volts and then ends when the plate potential reaches about 125 volts. Apparently, for the typical applications of the 5763 tube, secondary emission does not adversely affect the operation.

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Secondary emission on the 6AU6 tube

Secondary emission on the 6CL6 tube

Secondary emission on the 6146 tube

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