I upgraded to a large format Helix unit last year and moved my 1197C SI to the bow with the transducer mounted to my Terrova. I was never able to get it to work without significant interference whether running the trolling motor or not. In thinking about it over the winter, I think that my install may have a flaw in that I connected a Y cable to the SI transducer as well as the Terrova's universal sonar transducer. Anyone have any experience or knowledge that would bear this out? Waiting for open water to check it out in person.