I tried to search for the answer but could not find it. With all you high tech fishermen out there , this will probably sound like a dumb question. I just installed a terrova with 1-pilot and US2. I have a HB570 with a switch to go from transducer in back to TM. Heres the question. If I upgrade my depthfinder to SI type (HB898c SI) Will the US2 transponder do anything? I hope I asked that right. Also what is up with the donut hole. I have read about it and know what they mean. I slow troll most of the time. Is HB even the right choice. Thanks for the help. I hate buying things twice.
