[Lowfer] 1 watt in class " AB " into 32 Ohm load, BW - 600 KHz, and it's an audio amp

[JD]

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Unless I'm mistaken, I think the distortion in a Class " B " amp
might be a little too high, but on the other hand; at LF would it
even be noticable ?? Possibly so if it distorted the transmitted
waveform of a digital mode enough that decoding it would be difficult,
or impossible.
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I suppose that would depend on the particular digital mode.  The main 
distortion in a Class B push-pull amp will be at low amplitude 
levels...crossover distortion, if one were thinking in audio terms.  Any 
modes that require precise envelope shape at crossover for decoding aren't 
going to work that well in the noisy environment of LF anyway.

As I'm typing this, I see that Jay mentioned there are many modes that 
really do not require linear amplification in order to convey information. 
That's very true.  The main reason linearity is desired for some modes is 
that abrupt phase transitions occuring at full amplitude tend to produce 
wider emissions (and in some cases, can be rough on the final transistors) 
than if the "pure" waveform were preserved.  But that should not prove a 
problem in Part 15 operation unless one is too near the band edge.  And 
plain FSK modes, like RTTY, MFSK, DFCW and JASON, really have no need for 
linear amplification at all.  They can be handled as constant-amplitude RF 
with no problem at all.