[ohohyodafarted]

21AXP22 and 15GP22 are completely different animals.

The 21AXP22 has the phosphors deposited directly onto the inside of the faceplate and the shadow mask is mounted right behind the faceplate and attached to the rim of the front assembly. The metal funel of the rear section is heliarc'd to the metal rim of front section. Unlike the 15G, the metal components on a 21AXP22 are a single layer of metal that has no metal to metal laminations that could leak. When the front and rear sections of the 21 are brought together the flange that sticks out, is clamped together and then heliarc'd. The weld produces a very good vacuum seal.

Leaks on the 21Axp22 likely occur where the glass neck assembly joins the funnel, and where the faceplate is fused to the front flange assembly.