Hello Max,
I remember years ago hearing similar noise to what you described on another
DXer's MZ-R3 (R2?) Sony recorder. This is quite an "ancient" minidisc
recorder; I had presumed that these problems were gone from the newer
recorders. (Evidently not!)
The four models I've owned have had zero interference problems on shortwave
or mediumwave... all provided excellent DX recordings:
Sony MZ-R4ST
Sony MZ-R50
Sharp MD-X5 (CD/MD changer)
Sharp MS-702
However, my recordings have all been made from tabletop receivers with metal
cases. Perhaps the unshielded plastic case of your ICF7600GR is the problem
:^(
Guy Atkins
Puyallup, WA USA