Ok, I have a 597 trying to install on bow, ran ducer cable up motor shaft. Put everything back together. Hooked up power to power up front to check out. Bad interference when motor running. Removed ducer from motor and moved about 10 ft away, same thing. Pulled motor back apart removed cable and reassembled. Moved ducer and cable and finder to other side of boat, same thing. Got a section of shielded wire and ran from cranking battery to front down outside of boat, hooked up power wire, same thing. So I put my thinking cap on while staring at the back of my 998 which is mounted up front also ( stick steer ) removed connector and pulled out power wire ( which has the built in ferrite ) plugged to 597 and turned on motor no interference, put ducer back next to motor and still no interference. Called Humminbird, got the lady in tech help, explained what all I had done and she told me I had done everything I should and she is sending me a new power cord with the built in ferrite free of charge. May not ship until April 1'st but can't ask for any better service than that. I put the whole story in with the hope that my time spent might just help someone else out and shorten their trouble shooting in the future.