The boat I purchased has a Garmin 545s which is connected to a transducer but not an antenna and a Garmin 4208 which is connected to an antenna, but not a transducer. Is there a simple way to connect the two devices? I like using the 545 as a dedicated sounder and the 4208 as a dedicated gps, but it might be nice to use the bigger screen to see the bottom at times.