New Depth Finder

I recently installed an Eagle Fish Easy 2 depth finder in the front of my boat. I ran the transducer to the back and positioned it on the opposite side of the console depth finder transducer. Some of the time when I turn the new depth finder on it will tell me that it’s over 1100 feet deep, when the console finder regesters the correct depth. After shuting the unit off a restarting it a few times it will finally produce the right depth. What could I have done wrong in setting up this system so that it displays such figures?

If they are the same KHertz(200?) the signals will interfer with each other and give false readings.

LK