The shortwave automatic antenna tuner contains a 7 capacitors and 7 inductors, which allows it (with the largest configuration) to work effectively in a wide frequency band, overlapping the amateur radio HF band of 1.8-30MHz. Built-in lithium battery, 3.7V, 1800mAh, you can use Type-C cable to recharge it. Equipped with 0.91inch OLED display, you can see the data clearly. Automatically tuned and do not need control wires, suitable for most radio stations. Instructions: Connect the radio, ATU antenna tuner and antenna. For the first use, set the output power of the radio or power amplifier between 20-30W, or the high-power tuning can damage the antenna tuner. Set the radio mode, use frequency modulation mode. the antenna band to use, use 20-30W power in frequency modulation mode, press the radio PTT, observe the PWR and SWR of ATU antenna tuner. ATU button TUNE use: short press (less than 1 second) ATU button, it is in reset state, long press (more than 1 second) ATU button is in tuning state. Name: ATU100 Tuner Display: 0.91inch OLED display Charge: USB Type-C cable Battery: 1 * lithium battery, 3.7V, 1800mAh (included) Voltage: typical + 12 V (DC10-15V, 13.8V) Working frequency: 1.8-55MHz Maximum current consumption: 400mA Maximum working power: 100W Maximum possible measurement power: 150W Minimum power required to starts tuning: 5W Minimum possible measurement power: 0.1W Measurement step for power up to 10W: 0.1W Measurement step with power higher than 10W: 1W Power measurement accuracy: 10% Maximum installation inductance: 8.53uH Minimum installation inductance step length: 0.05uH Maximum installation capacitance: 1869pF Minimum installation capacitance step length: 10pF Number of panel buttons: 3 (ON/OFF, AUTO, TUNE) Item size: 160 x 90 x 40mm / 6.30 x 3.54 x 1.57in Colour: black : aluminum Package Contents: 1 * ATU100 Tuner 1 * Cable Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.