Quote:
Originally Posted by old_coot88
In some cases of extremely weak cathode emission in a B&W CRT, the pic is so dim it can only be viewed in a darkened room. The pic will have a 'silvery' cast, and high-luminance parts of the scene will actually be photonegative. That's because the control grid is commanding high beam current which the cathode can't deliver. And the grid is actually pulling available electrons out of the beam.
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This explains pretty well what some texts referred to as a "gassy" CRT or one not under full vacuum..
so maybe gassy is incorrect
, otherwise you may see some violet glow in, but not so much around, the electron gun.
Is this the same reason for the color smear (when increasing brightness/screen/bias) when a corresponding gun is weak in a color CRT?