Features: Due to being in the UHF frequencyband, there are certain requirements for the input and outputs cable, which require that the input and outputs are coaxials line with a characteristic impedances of 50ohms. If ordinary wire are used for connection, it may cause abnormal operation and strange phenomenas such as low outputs power and self-excitation. Due to the highs outputs power, do not directly connect theantenna to the outputs port of power Amplifiers!Please use 50ohm coaxials line of no less than 2meter to connect theantenna to prevent interferences from strong signal at close rangings. The Amplifiers is working properly! The outputs of power Amplifiers must be connect a 50ohm resistive load, it must be connect devices such asantenna. It must not be unloaded as it may damage power Amplifiers. Please be careful! Theantenna requires a standingwave of no morethans 1.5 to ensure transmission distance and Amplifiers safety! Input power: 20-23dBm (0.1-0.2Walt), can work even belows 0.1W, and the outputs power will increase with the increase of input power, finally reaching the maximums power point. Take advantage of powerful outputs of this Amplifiers to enhances your signal transmission and achieve better communication result. Specifications: Material:ABS Working frequency: 300-330MHz Maximums outputs power (P1dB): 8W (39dBm) @ 8V 1.56A Efficiency 65% Working voltages: 6-8.4V (lithiums battery supply voltages) Working current: 1.6A Inputs impedance: 50ohms outputs impedance: 50ohms Inputs and outputs terminalsSMA-k female head (external thread and internal hole) 8V powersupply, outputs 39.2dBm (8.3Walt), efficiency 66.6% Package Includes: 1x RF Widebands Amplifiers note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual color.