I am purchasing a Swan Mark 2 and I keep hearing it has an untuned input. Can some one explain what that means? I plan to use it with a Icom 7410 so do I need a tuned input to use it? I can get a tuned input circuit from a SB-220 for it if needed. If so, how do I go about installing/using it with the amp? Lacey K4LCY