Topband: Vacuum tube 100 years old today

[Tom Rauch]

On Nov. 16, 1904 Fleming patented the Fleming valve. The
vacuum tube is 100 years old today (exactly 46 years to the
day older than I am).

I was an electrical engineering student in the late 60's.
The electronics lab stock room was full of tubes and
sockets, and our benches had 300 volt power supplies. About
50% of our inventory and study was tube related. I built a
complete 500 watt HF station, receiver and transmitter, from
stock room parts in my spare time. Every component necessary
was in the stock room. From a textbook I still use,
"Electronic Amplifier Circuits" McGraw-Hill Electrical
Engineering Series 1961, comes the following quote:

"For many applications a relative newcomer, the transistor,
is replacing vacuum tube types because of the greater
inherent reliability, lower power consumption, and smaller
size. However, the complete replacement of the tube by the
transistor does not seem likely, for the latter has
shortcomings at high temperatures and high radiation
intensities and in the production of high power at high
frequencies. "

About ten years later I received a call asking if I wanted
any of those old tubes, tube related books, or HV bench
power supplies before they hit the dumpster.

73 Tom