02-28-2014, 08:27 PM
Hummmm Tubes of color! Brownish color on the inside of the glass is an indication that it was run hard and put away wet. Don't see it much in receiving tube but in power tube like rectifiers, horizontal output, and RF output type transmitting tubes.
White on the inside indicates there's air inside. This tube is bad.
Terry
White on the inside indicates there's air inside. This tube is bad.
Terry