Diddug1221,
The 556TID-HWD will connect directly to the FCV-588, no matching box needed.
Your question about the matching box is a good one. Our matching box (MB-1100) is an external diplexer. Some transducers (like the 556TID-HWD) have internal diplexers. So what exactly is a diplexer and why is one needed. Most smaller sounders (FCV-628, 588, DFF1 etc) have only one transmitter so when you have them display both frequencies the transmitter alternates between 50, 200, 50, 200khz. Having only one transmitter means that only one pair of wires are actually going to the elements. Yes the transducer has more wires for other functions like temperature and the ID. Most 600w and some 1kw transducers have elements that resonate at both 50 and 200Khz, but the 556TID-HWD has separate elements that only resonate at 50 or 200Khz. So what is needed is a way to route the 50khz signal to the 50Khz elements and the 200Khz to the 200khz elements. That is the job of the diplexer or matching box. Basically it takes the combined 50/200 and splits the signal into separate 50 and 200 wiring pairs that is then routed to the associated transducer elements.
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