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Registered Member #11591
Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556
I'm not sure about triodes specifically, but vacuum tubes/valves are still used in large high power radio transmitters. For dealing with a few hundred kW in the MHz, they work pretty well.
Registered Member #19
Joined: Thu Feb 02 2006, 03:19PM
Location: Jacksonville, FL
Posts: 168
What improvements would today's manufacturing techniques bring? Tube performance? Longevity? Cost to Manufacture? I second the audio group as a strong interest.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
The Russians continued producing new thermionic valve designs long after development had all but stopped in the West, which lead to the production of some excellent miniature and sub-miniature valves.
Thermionic valves are much more tolerant of EMP and radiation than semiconductors, and some Russian miniature valve data I have seen includes high G force operation, suggesting their use in missiles, but I am only speculating.
You can make yourself an excellent little triode super-regenerative radio receiver, with a sensitivity of a few microvolts, great fun and sensitive enough to pull in a good range of short wave and VHF signals.
Registered Member #1749
Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497
I was just thinking Tubes are much easier to develop something new/improve VS semicondors.
I mean just the simplicity is awesome maybe even try a different approach to Electron flow vs Heating elements. Maybe laser to heat a thin Metal plate at 2W vs 40ish? It could be like the IGBT where you have the robustness of a transistor and the ease of driving like a Mosfet.
Registered Member #1749
Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497
Sorry that was a tired post didn't make to much sense my question is basically can there be efficiency improvements? I did a bunch on research and its not promising. :)
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
Vacuum tube development in the past advanced as a result of specific needs that arose. For different and more efficient processes for manufacture, first describe a need, and it will be met.
As to lasers heating thermionic cathodes, some vacuum tubes do not need heaters. Their cathodes develop a space cloud when an ionized gas pulls electrons off and heats it. An example is the 0Z4 tube, and 'instant start' fluorescent lamps.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
The Nuvistor series of triodes and tetrodes introduced by RCA in 1959 were metal and ceramic thermionic valves smaller than a thimble. They are excellent low noise performers (by valve standards) and the very small interelectrode spacing makes them good performers up into the UHF.
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Vacuum Triodes
