I am running a Helix 12, Gen 4, that uses the transducer thats incorporated in a Ulterra TM. Would I be able to connect this unit to a transom mounted transducer and switch back and forth between the 2 transducers?

Yes, one at a time (disconnect one and connect the other manually) if the transom transducer is the same type as the built-in Minnkota transducer.

There are three Helix 12 G4N models, which one do you have and what transducer is inside the trolling motor?

Thanks for responding Wayne.

My unit is a Helix 12 Chirp, MDI+. I have been looking at HB's website and found two model numbers of what I think will work, but I'm not positive.

# XNT 9 HW MDI 75T with corresponding part numbers 710295-1 and 710296-l.

I gwt much more sonar.detail with my SI transducer than my thru hull transducer but i cannot get depth readings when on plane.

Therefore i mounted a transducer switch on my console that both of my transducers are connected to and then connected that to the sonar portion of the Y cable that connects to graph.

Now when on plane i put my switch on Transducer 1 and as soon as i get off plane i switch to Transducer 2 for more.detail.

Im sure the best approach would have been to properly install the thru hull transducer in the first place, but it has been working for me.

Did you get this transducer switch through Hummingbird?