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Registered Member #230
Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284
We made some field emitting diodes and triodes @ work Due to the extremely small size we could run them at atmospheric pressure because the mean free path between anode and cathode was small enough to exclude air molecules.
Registered Member #1792
Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527
There's ongoing work with microfabrication to create vacuum TWTA amplifiers to operation in the 100's of GHz. Improved cathode materials are also needed for that to increase the power density I understand, which could potentially increase power densities at lower frequencies too then.
But even companies that were more focused on vacuum device amplifiers have had to add solid-state amplifiers to their lineup to remain competitive. Vacuum tubes have niches where they are the best technology today, but solid state is often the better solution today, either higher performance or lower cost or both.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
I've been looking at state of the art SiC power JFET's..... Some are good for 40A or more, and good for 1.2kV.... United Silicon Carbide produce them, and I think it's Mouser that supplies them..... In many cases they should pretty much be a direct replacement for a triode operating in class 1 (negatively biased grid), although I'm experimenting at lower voltages, with low impedence, high Q factor circuits..... There internal resistances are fractions of an Ohm....
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Vacuum Triodes
