On Sat, 20 Sep 2008 21:46:42 -0500, "Martin H. Eastburn"
wrote:

The silver looking stuff in Tubes is mercury.
The getter was a pan of mercury and it was excited by an RF probe after
the tube was sealed on the line to oxidize itself so when the filament
is heated to red to red-white in color it would last many hours.

I've made tubes that you could pass a lunch box through without touching
sides. The filament was as large as a pencil. It was a research tube.
The largest I have put my hand on was 15 feet tall. The smallest was just
larger than a pencil eraser.

I taught Tube design (circuit) and later, taught EE's who knew tubes
solid state. So I had to know both designs and show relationships.

Eimac was the maker of Power transmitting tubes. I think of pyramid tubes
and potato sized kilowatt transmitting rubes. TV and Radio as well as
military used them. I think I have one or two in the shop. They used
to advertise in ELECTRONICS magazine in the 50's. Those were the years.

Martin

Martin H. Eastburn

Mercury? I would think that any residual Hg in the tube would vaporize
with the heat of operation, presenting a real problem for the electron
emission getting to the plate. Any "gas" in a vacuum tube is usually
considered a bad thing.

I think that I had heard years ago that barium was most commonly
used.You did mention that it was oxidized, but I thought the oxide was
red in color. Most of my work with tubes was in lower power stuff, up
to, say, 6GL6, etc.

I remember there were some diodes (high current ?) that used mercury
in their operation, though.

The big ones are cool; I keep trying to get the engineer at our local
University station to save a defunct transmitter tube for me (I do a
weekly volunteer stint there as a DJ).

Joe