Quote:
Originally Posted by benman94
They look pretty rough (and white) around the edges. Assume the tube is bad until further testing proves otherwise...
My gut says the tube is a leaker.
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I concur with Ben. The getter on that tube is what you would expect it to look like if it was a gasser. Later tubes that I have seen, which were likely rebuilds done at RCA, have had HUGE getters. The getter on this tube is indicitive of those found in the initial production runs. All those getters were very small, almost insignificant little getters. I will never understand why they used such tiny little getters for such a large tube volume, because as later examples have shown, there was plenty of room to flash a much larger getter in the same location.
I currently have a NOS RCA rebuilt tube for a Westinghouse chassis that I am working on for a client. It has a production date in the early 1960's. The getter flashes on that NOS rebuild tube are about the size of a silver dollar. I also have a gassy tube with the same large getters, so the size of the getters is no guarantee that the tube is good. This proves that even after RCA rebuilt a worn out low emission tube that was known to be under vacuum, the process of rebuilding the previously "under vacuum" tube could cause the newly rebuilt tube to spring a leak where there was no leak before.
I have seen only a small number of 15Gs with these huge getter flashes. But of those tubes with the large getter flashes, I have only seen one that was gassy. It seems the original early production 15Gs with the tiny little getter flashes have a higher failure rate. It is possible by the time RCA started rebuilding 15G's, maybe they had revised their production process so that they had a better probability if producing a rebuilt tube with large getters that would hold vacuum.
Too bad we will never know the real truth about what RCA may have done in late production rebuild tubes to increase the reliability of those bottles.