CRT Sizes

Panasonic (MEC) 180DVB22 8" EM focusing tube

For all intents and purposes, CRT’s come in three sizes; 7, 8, and 9”.  (Some Sony 7” tubes have a useable 5.5” raster, but we’ll get to that later).

The measurement is taken from corner to corner on the front of the tube face. Different manufacturer's have been known to rate the same tube as slightly different in size however. To avoid confusion, most enthusiasts (and this site as well) always refer to tube sizes by their actual size.  For example, we consider a NEC PG to have 8" tubes, not 7" as NEC sometimes would lead you to believe as the tubes are actually the same size as in the higher end NEC XG models.  (Who would have ever thought that a manufacturer would downgrade their specs on purpose?).

The larger the tube size, the more resolution the projector tube will be able to display as the picture that is being projected onto a large screen starts from a larger tube surface.

In general, a larger tube will also produce more brightness. Something to keep in mind if you want to have an especially large screen.

Naturally, a larger tube also costs more to make, which is why 9” projectors are expensive to buy and expensive to retube.

In general, most video-only and entry-level data grade projectors are 7”. Mid grade projectors use 8” tubes and the top of the line are 9”.