[Elecraft] K3 CW sidetone oddity

[Phil Hystad]

I am a new owner of a K3 and still learning...

Today, for some strange reason my sidetone in CW on the 20 meter band seems to be producing two notes and not a single pure note.  That is, it sounds more like the button tones of a push button phone then a pure sinewave tone.

This is only 20 meters.  All the other bands seem to be "normal".  But, being a new K3 owner I am not sure what normal might be or if this is some option that I have some how slipped into.

I don't know if I did anything to do this.  I had a perfectly fine CW QSO on 14054 KHz two hours ago but then I was away for a little bit.  When I came back, since my grandson was sleeping upstairs I decided to put the headphones on.  I sent a QRL on the frequency to test business and low-and-behold, the CW sidetone was weird.  I unplugged the headphones and the same condition existed on the speaker (built-in to the K3).

Can someone explain this?

phil, K7PEH