[Elecraft] K3 signal at 28004

[Hank Hanburger]

I too noticed this signal this past weekend while doing some S&P in the ARRL 10 meter contest.
I have no other Elecraft accessories and have an upgraded K3 in the 6000 range serial numbers.My signal is audible from about 28.003.75 to 28.005.64 transitioning from low pitch to high withthe shift up in frequency.  The peak signal strength is about S7-8 at about 28.004.
As others have suggested I would believe it is internal to the K3.
Happy Holidays to all and 73HankK3YDX