DuMont Royal Sovereign

[N2IXK]

My understanding of the 30BP4 problem is that because the tube was not aluminized, getters could only be used in the neck, rather than up inside the funnel area, because the getter flash would produce visible barium patches on the phosphor screen.

Unfortunately, with the very large surface area and evacuated volume, more getter area was needed than was able to be used inside the neck, leading to excessive gas and poor tube life.