Quote:
Originally Posted by wkand
I am assuming that this tube has a metal cone and glass face, similar to the 15G.
Correct?
|
Wrong, but close. The 15G has a glass cone(and I'd assume it is the same for the 15H). The face of any color tube is attached to the cone fairly late in the manufacturing process because the shadow mask has to be installed and before that the screen has to be coated in phosphor....Neither of which is practical with the screen bonded to the cone. It would be like building a ship in a bottle.
The thing is that if they heated the glass enough to fuse it would burn the phosphor and warp the shadow mask. To deal with that issue they built the cone and face with metal rings bonded to the glass where the two pieces of glass would have normally have been bonded to eachother in a monochrome CRT. They would then phosphor the screen, insert the the shadow mask then seal the face to the cone by using a special low temp welder to fuse the metal rings together.
The rings were soon done away with in favor of low melting temp 'frit glass' which was much less leak prone then the metal to metal and metal to glass bonds of the rings.
The only metal cone CRTs I'm aware of are the pre-15G developmental types (the 4 digit designations of which escape me at the moment), and the production type 21AXP22.
All metal cone(and tubes with metal to glass seals) CRTs were very leak prone and not long after they were developed they fell out of vogue because of that.