‘Tubes’ Category

brown-black getter flashing does not mean ‘Used’!

Discolored getter flashing (brown or black marks) does not mean that a tube was used. This fiction is believed by both uninformed buyers and seasoned tube jockeys. This myth seems credible because some new tubes have perfect shiny mirror getter flashing; therefore the assumption is that brown or black stains in the getter flashing must indicate a used tube. The myth says that the more brown/black discoloration, the “more used” the tube is. Wrong.

Excerpt from Electronics Magazine

Excerpt from Electronics Magazine

The purpose of the tube getter and flashing is to remove gas inside the tube envelope during manufacture. This discoloration myth can be quickly debunked by reading the article in Electronics magazine, October 1950, entitled “Getter Materials For Electron Tubes”. The article explains that if the getter is vaporized very slowly during the manufacturing process, “the first barium atoms evaporated will absorb the gas present so that the remaining getter is deposited in a very high vacuum, exhibiting a shiny mirror.” If the getter was flashed very rapidly during manufacturing, then “the getter mirror will be discolored due to the dispersion of the barium.” The article then explains that the discoloration “does not mean that the getter is contaminated, but merely that the deposit is finely divided and therefore absorbs light.”

Several photos of NOS tubes below demonstrate this myth.  Likewise, I provide photos to demonstrate how the flashing looks when a tube is actually used. Let us proceed…


Marathon MX-280 Globe tube MESH PLATE

Here is a rare tube — a Marathon MX-280 Globe #80 rectifier tube featuring MESH PLATES construction!  Not only that, but each section tests very strong Emission, comparable to an NOS #80!

Mesh Plate Marathon MX-280 Globe rectifier tube

In 18 years of collecting, I do not remember ever seeing another Mesh Plates #80 tube.  Look at that Glow!  You can see right through the Mesh Plates into the filament!


Identifying NATIONAL UNION tubes

This article provides examples of NATIONAL UNION-manufactured tubes.

NATIONAL UNION was another quality USA tube manufacturer with most production dating from 1930s to 1950s. Their production numbers were significantly smaller than the big name brands (RCA, Sylvania, GE).

The NATIONAL UNION (EIA) code number is “247″. Here is an example:


Identifying RAYTHEON tubes

This post provides examples of Raytheon manufactured tubes.

Raytheon was an extremely high quality USA tube manufacturer with prolific output, covering both civilian issue and a vast majority of US Military parts production. The Raytheon (EIA) code number is “280″.

Here is an example:


Identifying GE (KEN-RAD) manufactured tubes

This article provides examples of GE (KEN-RAD) manufactured tubes.

GE was one of the most prolific tube manufacturers in US history, and many companies sold GE tubes repackaged under their own brand name. The GE factory EIA code number is “188″ and proves GE was the true manufacturer, although there are a few rare exceptions to the “188” rule.  Here are several examples:


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