Rebuilding Metal Cone CRT's

[Duke Nukem]

Yep, what I was trying to get to was confirmation that if a metal cone tube had gone to air a rebuild was less likely to be successful.

In the UK, the metal cone was a short lived solution for larger screens (generally 16"), very soon replaced by all glass 17" designs, so the metal cones are quite rare. Despite being rare, the ended up in lots of console sets that aren't particularly valuable today so the tubes aren't really worth rebuilding. However HMV did an oddball 21" metal cone model and that would definately be worthwhile rebuilding, but if success is unlikely as tube had already gone to air then again not worth trying.

TTFN,
Jon

[Eric H]

Metal cones were popular here too in the late 40's early 50's.
There's at least one 8" type, several 16" the 21AXP4 color tube and of course the 30BP4 used in the Dumont Royal Sovereign.

It would seem that size matters in how well they hold vacuum, all the 16" tubes I've had including a 50 year old, NOS in the box 16AP4 were just fine, many of the 21AXP4's seem to have gone to air as well as a lot of the 30" tubes.

There were some rectangular tubes with metal cones too, I don't know their numbers off hand.

The plus side of the metal tubes is they are very light, also the face plates are precisely made so there's no distortion.

Someone here had a 21AXP4 successfully rebuilt, it was under vacuum to start with though.