AT140 HF Antenna Tuner

Although listed as an "option" by ICOM, virtually every marine SSB installation will require the use of an AT-140 antenna tuner. This is true whether you use a long wire/insulated backstay antenna, or a fiberglass whip - since chances are these antennas won't have an impedance that exactly matches the 50 Ohms required by the M802 transceiver.

It turns out that even if you do find and install an actual 50 Ohm antenna, its performance will still not be satisfactory, since all marine frequency bands will not be available. Furthermore, such an antenna would be huge - hence the use of the antenna tuner.

The antenna tuner electronically matches the impedance of the antenna you use, to the 50 Ohms required by the M802 transceiver.

The operation of the AT-140 is "black box" and completely automatic. All it needs is the proper connections.
It can be installed out of the way, but should be as close as possible to the base of the antenna. On a sailboat, this is usually the lazerette.
The AT-1400 is weather protected, so it can be installed in a damp enviroment.