Icom IC-7000 Instruction Manual - Page 123

10 ANTENNA TUNER OPERATION ■ Optional AT-180 automatic antenna tuner operation The AT-180 automatic antenna tuner matches the IC-7000 to the connected antenna automatically. Once the tuner matches an antenna, the variable capacitor setting are memorized as a preset point for each frequency range (100 kHz steps). Therefore, when you change the frequency range, the variable capacitors are automatically preset to the memorized point. NOTE: • The AT-180 can match both HF and 50 MHz bands. However, operation is different for the HF and 50 MHz bands. • When connecting the AT-180, the IC-7000's output power must be set over the 10 W. Otherwise, the AT-180 may not be tuned correctly. (AT-180's minimum operating input power is 8 W.) CAUTION: NEVER transmit with the tuner ON when no antenna is connected. This will damage both the transceiver and antenna tuner. The AT-180 cannot be used for the 144/430 MHz bands. When operating on the 144/430 MHz band, pushing [TUNER/CALL] selects the call channel (p. 100). [TUNER/CALL] D Tuner operation • For the HF band: Push [TUNER/CALL] to turn the tuner ON. The antenna is tuned automatically during transmission when the antenna SWR is higher than 1.5:1. • When the tuner is ON, " " indication appears. • For the 50 MHz band: Hold down [TUNER/CALL] for 1 second to tune the antenna. If " " indicator blinks slowly while transmitting, hold down [TUNER/CALL] for 1 second again to retune the antenna. D Manual tuning 9 During SSB operation on HF bands at low voice Through inhibit (HF bands only) 10 levels, the AT-180 may not be tuned correctly. In such The AT-180 has a through inhibit condition. When cases, manual tuning is helpful. selecting this condition, the tuner can be used at poor Hold down [TUNER/CALL] for 2 seconds to start manual tuning. • CW mode is selected, a side tone is emitted, and " " indicator blinks; then, the previous mode is selected. SWR's. In this case, automatic tuning in the HF bands activates only when exceeding SWR 3:1. Therefore, manual tuning is necessary each time you change the frequency. Although termed "through inhibit," the tuner will be set to the "through" configuration if the If the tuner cannot reduce the SWR to less than SWR is higher than 3:1 after tuning. 1.5:1 after 20 seconds of tuning, " " indicator disappears. In this case, check the following: CONVENIENT • the antenna connection and feedline • the antenna SWR (p. 36; meter function) • Tuner sensitive condition (HF bands only) If you require critical tuning at any time during transmission, select the tuner sensitive condition. See page 131 for selection. • Automatic tuner start (HF bands only) If you want to turn OFF the tuner under conditions of VSWR 1.5:1 or less, use "automatic tuner on" and turn the tuner OFF. See page 130 for turning the function ON or OFF. 114