User manual ICOM AT-120

[. . . ] 4 t Spring washers (M6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 y Nuts (M6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 u Hex head bolts (M6×50) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 i Self-tapping screws (A0 6×30) . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] Simple installation Installation is simple. Just connect the control and antenna cables. 45 memories for shorter tuning time To decrease the tune-up time, the AT-120 automatically stores the matching conditions for up to 45 frequencies. Re-tuning for a memorized frequency takes approx. Super capacitor for memory backup Even if the AT-120 is not used for approx. 1 week, the built-in super capacitor backs up contents of the 45 memories. Low power tune up The AT-120 emits low output power during tuning. This feature reduces the possibility of causing interference to other stations. Tuner through function The tuner through function is built into the AT-120. This function helps improve receiver gain, depending on the antenna element length used, and operating frequency. TABLE OF CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii 1 ANTENNA SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . and a good ship's ground is not available, connect a counterpoise. 1/4 radial for each band Ground terminal DANGER!NEVER connect the ground terminal to the following points. These connections may cause an explosion or electric shocks: ­ Gas or electrical pipe ­ Fuel tank or oil-catch pan AT-120 IMPORTANT!The mounting plate is NOT connected to the AT-120's internal ground. Ideal ground points One of following points is ideal: ­ External ground plate ­ External copper screen ­ External copper foil (quarter wavelength) radial for each band is suitable for a counterpoise. Install the counterpoise directly below the AT-120's ground terminal. Insulate the ends of each radial from other metal objects. Layout the radial horizontally and as straight as possible. L : Counterpoise length for the operating frequency [m] f : Operating frequency [MHz] L= 300 1 × f 4 1/4 Good ground points If electrically connected to sea water, one of the following points is usable: ­ Stainless steel stanchion ­ Through mast ­ Through hull ­ Metal water tank [Example] At an operating frequency of 16 MHz, use a counterpoise with the following length: L= 1m Undesirable ground points AVOID the following points, if possible. These connections may cause noise or electrolysis: ­ Engine block ­ Ship's DC battery ground 300 1 × 16 4 39 inches 4. 7 [m] Ground cable For best results, use the heaviest gauge wire or metal strap available. Make the distance between the AT141's ground terminal and ship's ground as short as possible. Supplied ground cable can be used for ground connection to a through mast. Confirm that the through mast is electrically connected to sea water. Electrolysis All ground cables from the AT-120, HF transceiver, etc. [. . . ] w Cover both the antenna and the control cable connectors with rubber vulcanizing tape and fix it with a vinyl tape to prevent water seeping into the connector. r Connect the coaxial cable and the control cable to the transceiver as illustrated below. t Ground the transceiver, AT-120 and shield cable of the control cable via the ground terminal. · See p. 2 for grounding details. IMPORTANT!-- AT-120 NEVER ground the AT141 via the mounting plate. [. . . ]