thank you for your answer.
My 7000 is connected to the radio interface of the 993B using an original MFJ-5123I cable.
Please also note that when I push the tune button on the 7000, the "Reverse" needle of the SWR meter of 993B has a pronounced forward dip and the 993B emits a tone. Immediately afterwards, the needle goes back to the initial position. No power from the IC-7000.
The needle also dips when I change band.