I have an interference question and am new to electronics. I have a Hook 2 4x on the bow that runs off the trolling motor transducer (motor guide xi5) and an HDS Live in the stern that has a separate transducer. When they are both on the live unit interferes with the hook unit in water deeper than about 10 feet. It causes the hook unit to mark dozens of fish that are not there. Turning the HDS unit off obviously fixes the problem. Is there anything I can do to solve the problem or am I stuck with it? I have tried changing sonar frequencies in the HDS unit but it doesn't seem to help. Thanks.

When 2 units are running the same frequency and the cones cross you will get interference. You either shut one off or replace the unit with a unit that runs a different frequency. 

That's what I thought but it doesn't seem to matter what frequency I run the HDS unit on. I'll play with it a bit more next time out on the water. 

If I'm not mistaken, when you shut off one frequency or another on the dual frequency units, it really doesn't shut off the frequency, just hides it, which is why the interference still exists.

Ok that makes sense. Thanks.