[1100 man]

Hi Aaron,
The first generation of colour TV's from the late 1960's, used delta gun CRT's. These required a whole array of convergence adjustments to get the three colours to align reasonably well over the whole screen. They also needed a very large yoke assembly around the tube neck to achieve this. Converging one of these sets takes a while and is an art in itself. They don't like being moved about too much either as this can upset all the adjustments. The three guns in the tube neck are arranged in a triangle and the phosphor 'dots' on the screen are also in triangles.

Then in about 1973/74, the PIL tube arrived. I don't know who developed it but I first came across it in the Thorn 9000 sets. It stands for 'precision in line' and the three guns are mounted next to each other in a line. Due to improved design and manufacturing tolerances, these needed much less correction to get the three beams to align. Part of that correction, though, was to accurately set the exact angle of the scan coil assembly during manufacture. That's why trying to rotate them could cause convergence errors. The setting of the coils usually involved the use of rubber wedges jammed under the coils and glued in place.

If you look closely at your screen, you will see the three coloured phosphors are arranged in vertical stripes.
The PIL tube was further developed & refined, but really remained until the end of CRT production.

CRT's certainly do wear out. The emission (the amount of electrons that a gun can produce) decays with use generally giving a low contrast, smeary picture often with a noticeable colour tint. Your tube looks in excellent condition.

CRT's are capable of giving excellent pictures although the resolution is not that great. They have served us well and were an amazing technology. To be able to mass produce them was an incredible achievement.

All the best
Nick