[Elecraft] K3 cleanest signal possible

[Ian White]

>The OP was more about Phase Noise that is emitted by the Radio.
>
>Here is Wayne's response to the OP.
>BTW, Jim's call should be K9YC as Wayne corrected later.
>
>( See W9YC's study of transmit phase noise and keying bandwidth of various
>transceivers:   http://audiosystemsgroup.com/TXNoise.pdf )
>((((73)))) Milverton. / W9MMS
>

The discussion galloped off in the directions of phase noise and audio quality, but the OP didn't actually specify what he meant by "clean".

Had he mentioned IMD, the discussion might have gone differently. In static 2-tone tests, the K3's IMD performance is adequate for a "12V" transportable transceiver, but the high-order IMD is not very good at all (mostly due to the MOSFET driver). 

However, the K3 pulls ahead again in dynamic IMD tests with real-life speech modulation, thanks to its almost unique "light touch" ALC system. The K3 implements ALC in the way that the engineers at Collins (the inventors of ALC for SSB) originally intended. The RF drive is pre-calibrated across a range of power levels on each band, leaving the ALC to deal with any moderate overshoots. 

By contrast, most (all?) other transceivers still seem to use an ALC loop with very high gain to control the power level, band-to-band gain variations, clipping overshoots and "whatever else", and the high loop gain creates major dynamic overshoots of its own.


73 from Ian GM3SEK