[Elecraft] K3 unknown Signal

[Bill Wiehe]

This morning I noticed an S3 sustained tone signal at 7.025 on my K3. 
The rig is connected to the dummy load and I was unable to detect it
on my other radio. I suspect the K3 is therefore generating the tone. 
Interestingly, the signal disappears when I switch to my 500Hz filter. 
As K3 nu-bee, I may have something turned on that should be off. 
Any insights would be appreciated.
Thanks,
Bill - W0BBI