[Amps] Why are we building amps rather then transmitters? (Tubes vs. Solid State)

[Dan Mills]

On Thu, 2012-05-03 at 18:20 -0400, W2XJ wrote:
> A good portion of this has already been done. Check the HPSDR group. 
> Also look at the ADAT. The final hurdle is to do this at the legal limit.

Yea, I know about the HPSDR project.

AM is really the easy case as there is no phase modulation component, so
EER is really simple and class E (as long as you don't want easy tuning
across a wide band!) rules. 
SSB is far more tricky as there is significant phase modulation
component in play, and unlike AM the envelope goes through zero
amplitude, so polar loop is really tricky.  

A sort of halfway house would be to export the I/Q pair from an
essentially conventional rig (maybe along with a constant amplitude
carrier reference), this would allow an almost conventional amp to take
advantage of whatever efficiency and linearisation opportunities were
available while still retaining fallback to 'simple minded amplifier'
functionality. 

For me, 'legal limit' is somewhere around 450 - 500W (400W at the
feedpoint by the rules), makes things a bit easier.

Regards, Dan.