Sfeerplaatje (Algemeen)

door Maurice ⌂ @, Dordrecht, 19.11.2020, 00:25 (6 dagen geleden) @ Onno

Helder blauw is niet bezwaarlijk.
Alle overige richting het paars is wel.

In the 1960’s Sylvania printed the following article:


Blue Glows are not tube detriments per se. They are, however, suspects in the eyes of many receiving tube users for lack of a full understanding of their origins. There are several types of Blue Glow which can be described as follows:

Blue glowFLUORESCENCE - this type of glow is usually violet in color and most noticeable around the inside surface of the glass bulb. It is most pronounced on power tubes and is the product of electron bombardment of the glass taking place within the tube. It generally has no adverse affect upon receiver performance, and in fact, tubes displaying this phenomenon are particularly good with respect to gas content.

MERCURY VAPOR HAZE - is a blue-violet glow associated with those tube types which rely upon mercury vapor for proper operation. In such cases, the blue glow should be evident indicating proper operation. (Note from thetubestore: Mercury Vapor tubes are rare and almost never found in common guitar or hifi amplifiers)

Gas RegulatorsGAS - produces a blue haze, generally confined to the vicinity of the mount structure. The proper function of gas types such as thyratrons, voltage regulator and voltage reference tubes, requires the presence of this glow as an indication of proper tube operation. Some voltage regulators use neon instead of argon and as a result exhibit a pink-orange glow. It is, however, a distinct detriment in vacuum receiving types, where the presence of gas in large amounts can cause malfunction of the equipment.”

To summarize, almost any blue glow you see inside a tube is perfectly fine and will not cause any problems in your amplifier. However, if you see bluish/violet glow around a single element such as a wire for example, it could indicate an air leak into the tube. There could be a small crack in the glass or a leak around one of the tube’s pins. A tube showing this needs to be replaced.

"I haven't even turned this on to see if it works because as long as I don't it might"

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