Westinghouse K840CK15 Restoration

[Electronic M]

Originally Posted by etype2

As a side note, anyone know why Westinghouse used copper cladding on the chassis. Admiral did the same thing.

Also, what do the designations GP in 15GP22 and XP in 21XP22 mean? XP for experimental?

P4 = monochrome phosphor, P1 =green oscilloscope phosphor, P22= tri color phosphor for color TV. Previous letter(s) is a randomly chosen identifier picked when the tube is registered as a new type with IIRC the RMA. There were other types of phosphor (for a variety of applications including radar) with their own P number (Wikipedia has a list). A 7JP4 tv CRT and a 7JP1 scope CRT are identical parts asside from phosphor color and you could interchange them with each other with out issue (as long as you don't mind a white scope trace and green TV picture).

In 1968 the government passed a law that TV screens had to be sold and CRTs identified by viewable area diagonal and not envelope diagonal. Many tubes made after that point had a V as the first letter and the diagonal number was 2" smaller....So a 1966 25XP22 might become a 1969 23VXP22.