[Elecraft] Side Tone

[Charles]

I built K2 Nr 413 and made lots of CW contacts, the built in Mojo was great.
I stopped using it because the crystal oscillator in the side tone was 
not a pure sine wave and it became offensive to my ear. I only use CW.

I have been informed by a K2 op that the more recent versions have a 
better side tone. If this is so then I may consider building the K2/100.
Could some one please help me with this decision?

Charles