Garry, Jeff,
Again thanks for the feedback.
I decided to start eliminating all possible sources, so I removed the tuner, still an issue (thankfully because I like my 998) then bypassed all accessories (one by one including cables) and directly routed the output of my FT-991a to my antenna (still a problem) but there is a coax coupling in the line (to the antenna) so I checked that, it was a little loose. After tightening it the problem was gone, So I tightened some more (with pliers) and the problem is back.
I do think it is the source, I doesn't look "clean" , I'm going to cut the connector off and replace it until I have time to replace the cable with one that is long enough to not need a coupling. I have a new roll of M&P Airborne 10 calling out "Use Me"?
So I think Jeff you were correct in your assessment. When I finally replace it I'll post again hopefully with my success.
73
Mick VA3EPM
Mick