Emission and Cut Off

[ChrisW6ATV]

Originally Posted by bandersen

Another way of thinking about it is that good emissions = good brightness and good cutoff = good contrast.

Is it possible to have a CRT with good emissions and bad cutoff? What would the result be?

The B&K CRT testers I have used at home and work have a "set cutoff-add one meter division" function if I remember right. Near-dead CRTs at work would never move that pointer at all, until I rejuvenated them, then maybe it worked properly.

[N2IXK]

Good emission but bad cutoff would give you an overly bright picture, lacking in contrast, as the grid cannot effectively "pinch off" the beam current to produce the dark parts of the image.

Some rejuvenators can actually cause this problem, by eroding the control grid aperture when drawing the heavy current used to restore the cathode.

[vts1134]

Originally Posted by N2IXK

Good emission but bad cutoff would give you an overly bright picture, lacking in contrast, as the grid cannot effectively "pinch off" the beam current to produce the dark parts of the image.

Could that be what I'm experiencing here? I am adjusting my brightness control up and then down.
http://www.youtube.com/watch?v=LsUmkal9L9s
The lower I set the picture brightness the better the picture. The best picture is actually dimmer than my camera can pick up and must be viewed in a pitch black room. I thought that the picture was loosing focus, but perhaps it is loosing contrast and that makes it look like it is loosing focus.

[old_coot88]

Originally Posted by vts1134

Could that be what I'm experiencing here? I am adjusting my brightness control up and then down.
http://www.youtube.com/watch?v=LsUmkal9L9s
The lower I set the picture brightness the better the picture. The best picture is actually dimmer than my camera can pick up and must be viewed in a pitch black room. I thought that the picture was loosing focus, but perhaps it is loosing contrast and that makes it look like it is loosing focus.

Might oughta clarify that the diagonally running bars are a camera artifact and do not exist.

[vts1134]

Originally Posted by old_coot88

Might oughta clarify that the diagonally running bars are a camera artifact and do not exist.

Should have mentioned that.
I found that cutoff was not the problem I was experiencing with my set.

[Geist]

Originally Posted by vts1134

I was experiencing with my set.

Hi All;
I would like to know more about that, Is that like becoming one with your set ?? Or a new religion ?? Or just something I wasn't taught in Basic Television ??
THANK YOU Marty