I have an esoteric question I probably should know the answer to

[old_tv_nut]

Originally Posted by zenith2134

As mentioned in another thread of mine, I am curious as to the behavior of the anode's h.v. during blanking state. I seem to recall reading how the high voltage raises with a blank raster but cannot verify this barring a quick check of one of my tvs. I realize that beam current drops to zero in this state...but what happens to hv.
It sure seems like there used to be more technical articles on the net when I first joined A.K./V.K. but that they're tougher to track down nowadays...
Should hit up a library to brush up..

You mean a black raster, right? It doesn't change during the brief horizontal blanking due to the filtering of the dag capacitance. The question of how much it changes from black (or dark) scene to all white scene depends: on the older style shunt regulator sets, the HV is essentially constant, because the regulator works by making the total current constant. In later sets, where regulation comes from adjusting the drive, there can be some variation, which normally would cause raster size to breathe, but is compensated by the variable loading of the B+, which affects the scanning current. (All the above about later sets is IIRC!)