-- R L Measures <r@somis.org> wrote:
Hi Rich,
>> was the plate/anode white hot?
>>
>>
>> Hi Rich,
>> Not if the tube is operated at 90% efficiency.
>And if the 4-250A is operated at 110% efficiency in high humidity,
>frost will form on the envelope during lengthy transmissions?
Fortunately, farsighted tube designers included the heater/filament
to circumvent this likelyhood.
>Seriously, Marv, after looking at the constant-current curves, I
>don't see how 90% is do-able.
Take a look at the RCA article. It shows how it's done.
>>
>> You may want to review Kahn's Envelope Restoration technique in the
>> Proceedings of the IRE, Vol. 40, July 1952, pp 803-806
>>
>> Some further details are shown in the Proceedings of the IRE, Vol.
>> 44, December 1956, pp 1706-1712. The curious may wish to
>>recalculate the numbers in Appendix One with a 90% efficient RF
>>power stage, in lieu the 80%, plus a 90% efficient Class D audio
>>modulator instead >>of the (55% efficient) 1950's vintage Class B
>>stage.
>>
>> An article describing a 90% efficient RF stage is posted on my
>>webpage at:
>>
>> http://wc6w.50webs.com/wc6wamps/index.html?fr422.html
>>
>> Soooo...now, how much power does the plate have to dissipate,
>>running 2KW peak, if it's 90% efficient? Don't forget that the
>>average power of a (two-tone) SSB signal is only half the peak.
>>The tube won't even glow.
>I do not believe that 90% is possible in a linear amplifier that
>can be QSYed. At 14-cents per kWH, the yearly operating cost
>difference in my ARS between 60% and 90% would be under a US$. .
>
>cheers, Marv
It does take a total of 9 variable coils & caps all motor driven.
I'm not clever enough to chain them together.
True, it is not economical. I did state that this was an
impractical approach in my first note.
However, if the FCC should happen to change the rules so
that "power" is measured at the AC cord, then we might be a mite more
circumspect as to how we use it. :-)
>R L MEASURES, AG6K. 805-386-3734
>r@somis.org
73 & Good morning,
Marv WC6W
http://wc6w.50webs.com/
*
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