Description:      This antenna tuner ATU-100 is an automatic tuning antenna. When installing and using it, please try to use a short coaxial cable to connect the short wave machine to the in end of the antenna; use the out port to connect your antenna. When the ATU-100 detects that the tuned transmit power is reached and the standing wave value is greater than 1.3, the tuning can be started, and after the tuning is completed (within the ability of ATU-100, if your antenna is not well matched, it will not be able to be reduced below 1.3, please adjust the antenna), you can perform high-power communication test. The finished board comes with a 128*64 OLED display screen, which takes into account power saving and display font coordination; please pay attention to the consistency of the data cable (dat clk) when installing the screen.                 Technical Parameter:      -Allowable supply voltage range: 10-15V DC      -Maximum current consumption: 400mA      -Maximum working power: 100W      -Maximum measurable power: 150W      -Start to input tuning power: 5W (10W or more is recommended, and the maximum should not exceed 30W)      -Minimum measurable power: 0.1W      -Power measurement accuracy: 10%      -Minimum load inductance value 0.05μh      -Maximum load inductance value: 8.53μh      -Minimum load capacitance: 10pf      -Maximum load capacitance value: 1869pf            Other detailed technical parameters and schematic diagrams, documents, pcb source files and firmware can be downloaded from the following site:      https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards/tree/master/ATU_100_EXT_board                 Package List:      1 x Set of Automatic Antenna Tuner                 Note: This finished board is a network open source project, we provide a test and modification platform for ham without DIY conditions (or you are unwilling to solder by yourself).                                   The sound of the relay picking up proves that it has worked, but the screen does not show that the line is not checked                 1. Make sure the connection sequence of the screen cable is correct.                 2. Working mode and tuning transmit power of shortwave radio.