12LP4 with FANTASTIC emission...but weak cutoff..OK?

[miniman82]

Cutoff has to do with the ability to control the stream of electrons leaving the gun, so less ability to get proper cutoff at the proper voltage indicates a tube which will have decreased contrast- in essence, you have less headroom between full bright and full dark. My experience has been that tubes which test like this often work fine in an actual set, and I suspect many thousands of CRT's left the factory this way or developed a cutoff issue shortly after being placed into service. It's a bigger problem with color tubes of course, because it affects color tracking.