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Title: Gasey 572B tube. Post by: Knightt150 on August 05, 2018, 10:23:43 PM Hello: I just installed two new TAYLOR 572.B's in my amplifier, when I turned on the high voltage one of the tubes had patches of blue haze near the top of the tube the other tube was clear. The amp worked great no problem. Dose this mean the tube is gasey or leaky? I hate to tear it down and send the tube back it's part of a matched pair.
John W9BFO Title: Re: Gasey 572B tube. Post by: w4bfs on August 06, 2018, 11:17:47 AM was the blue a pure or pastel color ? was the blue between the plate and the glass or inside the plate to the grid ? it matters for it describes what is going on here
Title: Re: Gasey 572B tube. Post by: Knightt150 on August 06, 2018, 09:34:31 PM Hello: Thanks for the comeback the BLUE was bright and only on the inside glass, not near the elements, mostly near the top of the tube. The tube is mounted horizontal in the amp and I could only see it under the glass at the top.
John W9BFO Title: Re: Gasey 572B tube. Post by: k4pf on August 06, 2018, 11:46:13 PM A blue glow on the inner surface of the envelope is called fluorescence, caused by the electron beam hitting the glass. It is not due to gas, and in fact is an indicator of a hard vacuum within the tube, the opposite of a "gassy" tube. A glow between the active elements of a tube is an indicator of gas. Title: Re: Gasey 572B tube. Post by: Knightt150 on August 07, 2018, 10:20:10 PM Hello: Thanks for the reply I have learned something about gassy tubes or non gassy tubes.
John W9BFO Title: Re: Gasey 572B tube. Post by: Tom W2ILA on August 12, 2018, 08:36:00 PM Im curious to know how those tubes are working. There have been reports of quality problems with the Chinese 572b's coming in batches. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
The old SB200 tubes are getting a bit soft. Tom |