I was wandering over on this guy's site .....effectrode.com He's a Brit. Anyway, on
http://www.effectrode.com/support/articles/ there are some interesting articles about tube history.
In his article about the 12AX7 he mentions (and has a drawing of) the RCA Harrison, NJ plant where RCA made tubes, a complex of brick buildings built in 188x which RCA bought from Edison in 1930. When I was in high school, about 1970, we went on a field trip to that plant and walked onto a floor where there were some number of tube making machines.
First, I was kind of amazed that RCA, the king of electronics at the time was operating out of these really old buildings. They absolutely looked like 188x. Second, the machines that made the tubes were completely fascinating.
We toured a floor in which tubes were being made and it was quite fascinating to see the machines which made the tubes. They were carousels perhaps 8 to 10 feet in diameter with perhaps 40 or so tubes in various states of assembly positioned roughly ten inches apart around the circumference. Every so often, just guessing from memory, about 30 seconds, the carousels would advance one position KA-CHUNK. Fed into the carousel were the glass 9-pin bases. At the next station, various mechanical arms extended and bent the electrode wires, or dropped in a grid or a mica spacer or picked up a small bit of sheet metal and bent same into the shape of the plate. Sometimes an arm would rotate into the space of the tube and perform a tiny spot weld. Finally, the "champagne flute" piece of glass was dropped over the tube and fused to the base at a station or two with gas torches.
Incredible machines, all chain-driven. No air cylinders and I don't think there were any solenoids. There was power to the machines for the tiny welders that welded the base pins to the various elements but I don't recall any signs of solenoids. Might have been.
At the end, a completed tube was ejected and gathered into some sort of tray.
It was completely fascinating to watch although it soon became clear that if you worked there, you would be driven completely mad with the repetitive boredom and rhythm of the machine operating!
Still, it was quite interesting, anybody who likes tubes would have been fascinated.
Topic: Learning about the construction of a vacuum tube (Read 6117 times)