[Elecraft] K3 FSK

[lyle johnson]

> This was last discussed a couple of weeks ago. I think the reason for this
> is that the K3 does FSK by generating audio tones in the DSP. These audio
> tones must pass through the SSB filter and what you are seeing is the effect
> of ripple in the filter passband. Other radios, I guess, generate a FSK
> carrier the same way they do for CW and actually frequency shift it.

The K3 directly generates FSK tones in a phase-coherent manner at the 15 kHz 
IF.  The output is then up-converted to 8.215 MHz, passes through the crystal 
roofing filter, then converted to the final RF output frequency.  No audio 
involved.

The "sidetone" audio for MON use is separately generated.

73,

Lyle KK7P/7 (Tucson AZ)