I installed a “Choke” (the Humminbird one, even though mine is a Lowrance) and it stopped the interference for me at least. Installed it right at the battery where my trolling motor and electronics are powered from.

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Heres the link to it: https://humminbird.johnsonoutdoors.c...e-interference

Cost is ~$25. Might be worth a try?? Good Luck!