Thank you Manfred for having the nuts to tell it like it is!!!
Especially the last couple of paragraphs and the statements that no
solid state mosfet amp is clean!
I am in the minority here, I'm not looking for a linear amp for HF. I
have no interest in ssb operation, except for casual ragchewing. I
mostly do DXCC chasing, and hope to get back into contesting. After
being off HF for more than 20 years, I came back hoping to find clean
solid state amps at reasonable prices. It looks like it's not happening
yet>>:
I'd like to point out that even the best bipolar transistors are far
from linear, look at the curve tracer results and see how severely the
hfe differs as the base current increases. The fact is evenn the best
conventional bipolar rf amps aren't linear! And there's no way to make a
mosfet linear-case closed.
I'm following all the discussions here and thank all who contribute to
these topics.
Art
<lot's 'of good stuff snipped>
> Like which? And are they really necessary?
>
> Some rigs are expensive and over priced, but some bring new technology
> with extremely clean signals.?
>
> Like which? I'm not aware of commercial ham equipment having extremely
> good IMD performance. I would like to know of any!
>
> We technically interested hams should take the lead in developing a
> type of modern legal-limit amplifier, that overcomes the problems
> making them so expensive now. For example, instead of having one
> lowpass filter per band, which is the reason for much of the bulk and
> cost of amplifiers, we should develop a transmitter that can work with
> a single lowpass filter. How so? Simple: Make use of the UHF
> capabilities of modern transistors to modulate the entire HF signal
> onto an UHF carrier, as a PWM signal or some other digital code, then
> pass the UHF signal through a high efficiency, high power switching
> stage, and then pass the output through a simple, single lowpass
> filter that strips the UHF signal and passes everything HF and lower.
> The harmonics of this amplifier would fall on UHF frequencies and be
> filtered out easily.
>
> We should definitely NOT keep copying the class AB push-pull linear
> amp circuits developed in the 1970s, with all their problems and
> shortcomings, as if there could be no other way in the world to
> generate clean HF signals.
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