[Amps] Any new tube research? (WAS) Re: New NXP BLF578XR 1200W LDMOS FET is "indestructible"

Ron Youvan ka4inm at tampabay.rr.com
Sat Aug 13 15:02:24 PDT 2011

Jim Barber N7CXI wrote:

> This discussion of "super semis" makes me wonder if anyone is still
> engaged in vacuum tube research these days. Could any of the basic tube
> wear points be improved on with modern technology? Could filaments be
> made to emit twice as long without degradation?

   I think only emissive materials that are more efficient at lower temperatures remain to be 
exhausted on this area.

> I just looked at the CPI Eimac site and I can't see where they're
> motivated or have the resources to innovate at the basic level. They
> list "Amateur Service" as a product category, which can't bode well for
> volume sales... Assuming MOSFET technology passes tubes by at high power
> levels, will they just go quietly into the night?

> I hope not - there's no second chances with current solid state devices.
> Generally speaking, they do not degrade gracefully... ;-)

   I do not think developing 30 kW of RF across 6 MHz (ATSC) can be developed with 30, 1.0 kW 
devices anywhere as cheaply or efficiently as one IOT tube.
   When you combine a bank of semiconductors with an bank of semiconductors and combine those with 
another gaggle of amplifiers the combining losses (from each amplifier having different gain) 
eventually eats up so much power, you loose too much efficiency to compete with one huge device.
    Ron  KA4INM - I've been carving my initials on trees and furniture all my life
                  'course I didn't use my own initials, I'm not stupid ... Earl Pitts 4-2-9

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