Purple pink is likely caused by the excess gas in the tube ionizing.? Unless it's a mercury vapor tube (don't think it's likely), soot and burn marks (not a getter flash) is not a good thing to see.

I'd worry less about the tube tester and a bit more about a replacement, IMHO.

Harvey

On 10/27/2021 7:53 AM, Richard Merifield wrote:

Actually it rises to about -50V when I let things warm up.

I am thinking it may be one of the EL86 tubes. I was assuming warmth meant it was probably glowing but now I have taken the shields off I notice only one glows an nice orange and the other one flickers and glows purple/pink. I notice the purple/pink glowing one has some soot/burn marks inside the glass. Photos attached..

Anyone down under in New South Wales have a tube tester :)?

Richard