Icom IC-7200 Instruction Manual - Page 72

9 ANTENNA TUNER OPERATION ■ Optional AT-180 automatic antenna tuner operation The AT-180 automatic antenna tuner matches the IC-7200 to the connected antenna automatically. Once the tuner matches an antenna, the variable capacitor settings 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-7200's output power must be more than 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. MODE TS TUNER FILTER SPCH TUNER NB NR ANF METER V/M 1 1.8 A=/B 2 3.5 SPLIT 3 7 MW 4 10 M-CL 5 14 AGC 6 18 COMP271 RIT . GENE SCAN 8 24 MNF 0 50 VOX 9 28 F-INP ENT BAND P.AMP ATT M-CH/RIT SET D Tuner operation • For the HF band: Push TUNER 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: Push and hold TUNER for 1 sec. to tune the antenna. If " " indicator blinks slowly while transmitting, push and hold TUNER for 1 sec. again to re-tune the antenna. D Manual tuning During SSB operation on HF bands at low voice levels, the AT-180 may not be tuned correctly. In such cases, manual tuning is helpful. Push and hold TUNER for 1 sec. to start manual tun- ing. • When CW mode is selected, a side tone is emitted, and " " indicator blinks; then, the previous mode is se- lected. If the tuner cannot reduce the SWR to less than 1.5:1 after 20 sec. of tuning, " " indicator disap- pears. In this case, check the following: • the antenna connection and feedline • the antenna SWR (p. 30; meter function, p. 60; Measuring SWR) Through inhibit (HF bands only) The AT-180 has a through inhibit condition. When selecting this condition, the tuner can be used at poor 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 SWR is higher than 3:1 after tuning. CONVENIENT • Tuner sensitive condition (HF bands only) If you require critical tuning at any time during transmission, select the tuner sensitive condition. See p. 68 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 p. 76 for the automatic tuner function. • PTT tune function (p. 76) The AT-180 is tuned when [PTT] is pushed after the frequency is changed (more than 1%) if the AT-180 is turned ON. This function removes the "push and hold TUNER " operation and activates first transmission on the new frequency. This function is turned ON in the set mode. 67