Icom IC-7600 Instruction Manual - Page 120

8 ANTENNA TUNER OPERATION ■ Antenna tuner operation The internal automatic antenna tuner matches the transceiver to the connected antenna automatically. After 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 setting. CAUTION: NEVER transmit with the tuner ON when no antenna is connected. This will damage the transceiver. Be careful of the antenna selection. 4 For your convenience When you purchase a brand-new antenna, or you want to change the antenna settings, you can erase the all of the internal antenna tuner preset points with "Tuner Preset Memory Clear" in others set mode. (p. 130) D Tuner operation ➥ Push [TUNER] to turn the internal antenna tuner ON. The antenna is tuned automatically when the antenna SWR is higher than 1.5:1. • When the tuner is ON, the indicator on the switch lights green. • While tuning, the indicator on the switch blinks. D Manual tuning During SSB operation at low voice levels, the internal tuner may not automatically tune correctly. In such cases, manual tuning is helpful. ➥ Push and hold [TUNER] for 1 sec., to start man- ual tuning. • A sidetone is emitted and the indicator on the switch blinks red while tuning. • If the tuner cannot reduce the SWR to less than 1.5:1 after 20 sec. of tuning, the indicator on the switch goes out. NOTES: • NEVER transmit without an antenna properly con- nected to antenna port in use. • When 2 antennas are connected, select the antenna to be used with [ANT] (MF1). • If the SWR is higher than about 1.5:1 when tun- ing farther than 100 kHz from an antenna's programmed preset point, push and hold [TUNER] for 1 sec. to start manual tuning. • The internal tuner may not be able to tune in AM mode. In such cases, push and hold [TUNER] for 1 sec. to manually tune. TUNER ❍ If the tuner cannot tune the antenna Check the following and try again: • the [ANT] connector selection. • the antenna connection and feedline. • the untuned antenna SWR. (Less than 3:1 for HF bands; Less than 2.5:1 for 50 MHz band) • the transmit power. (8 W for HF bands; 15 W for 50 MHz band) • the power source voltage/capacity. ❍ Tuning a narrow bandwidth antenna Some antennas, especially for the low bands, have a narrow bandwidth. These antennas may not be tuned beyond the edge of their operating bandwidth, therefore, tune such an antenna as follows: [Example]: Suppose you have an antenna which has an SWR of 1.5:1 at 3.55 MHz and an SWR of 3:1 at 3.8 MHz. If the tuner cannot reduce the SWR to less than 1.5:1 after checking the above, perform the following: • repeat manual tuning several times. • adjust the antenna feedline length. (This is effective for higher frequencies in some cases.) q S et 3.55 MHz and push and hold [TUNER] for 1 sec. to start manual tuning. w S et 3.80 MHz and push and hold [TUNER] for 1 sec. to start manual tuning. Even if the manual tune does not tune the antenna and the tuner turns OFF at the first time, it may tune the 113 antenna at the second time.