RE: Humminbird 858c HD DI
“No, it is not compatible….
There is no 100% correct answer. Technically, you can connect the US2 xducer to a DI fishfinder. However, due to the internal design of the DI units, the sonar performance will be less than optimal. In addition, they can only use the 200kHz frequency. Because of these issues, the official stance is that US2 and DI are NOT compatible (which is why they are not on the US2 chart).”
Oh well………….live and learn.