I had this exact problem with my 7000 as well on 40m only. Turned out to be RF in the shack. In the days before I had proper 1:1 Current BalUns in the feed coaxes. The culprit turned out to be a secondary feeder used to connect a SDR to a different antenna conducting RF back to the shack via the outer face of the coax braid. The moment I slugged the cable with some clip on ferrite sleeves at the shack end and a BalUn at the antenna end the problem disappeared.
