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from the my-vacuum-has-a-bag-not-a-tube dept.
More than a half century later, traveling-wave-tube amplifiers still dominate satellite communication. That's right—your ultrahigh-definition satellite TV and satellite radio come to you courtesy of vacuum tubes in space.
Of course, there's a huge difference between Telstar's 3.5-watt, 4-gigahertz amplifier and one of the dozens of highly efficient microwave amplifiers on, say, the DirecTV-15 satellite, launched earlier this year. The latest generation of traveling-wave tubes can provide up to 180 W at frequencies up to 22 GHz, with efficiencies approaching 70 percent and rated lifetimes exceeding 15 years. Though their basic function is the same—amplifying RF signals—just about everything else has changed: the design, the testing, the materials, and the fabrication.
...
And now, ongoing research into a new and potentially revolutionary kind of traveling-wave tube—the ultracompact and ultraefficient cold-cathode TWT—looks poised to deliver the first practical device by the end of this decade. These are exciting times for vacuum tubes. Here's why.
No cheating this time--read the article to find out why.
(Score: 2) by takyon on Friday November 27 2015, @04:56PM
http://news.sciencemag.org/physics/2012/05/return-vacuum-tube [sciencemag.org]
Throw those transistors away!
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Friday November 27 2015, @09:38PM
SciMag has decent content but their page construction needs work.
They could start with the Skip to main content link--which is completely broken.
.
Their page doesn't mention the Nuvistor. [wikipedia.org]
That considerably shrank the size of tubes. [g3ynh.info]
I remember encountering those in the tuners of RCA TVs in the 1960s.
.
The other big downside of a tube is the percentage of the energy those use to light the filament.
These cold-cathode things are a giant step in the right direction there.
-- gewg_