[Elecraft] Why not a KX4?

[Tony Estep]

Actually the KX3 is pretty hard to improve, but the one obvious
consideration is that the internal batteries should be LiPo. Another
possibility would be a different way to generate the oscillator freq to
ensure super-stability; even after the refrigerator procedure mine drifts
-3 or -4 Hz in a WSPR interval, which is right at the ragged edge. I can't
think of any other changes but others may.

73,
Tony KT0NY