Specification

This board display frequency with 4 blue LEDs. If current frequency is 87.5MHz, long press K3, the second LED flash 8 times, the third LED flash 7 times, and the forth LED flash 5 times.
K1: Short press, plus frequency 0.1MHz, long press, frequency plus 1MHz
K2: Short press, reduce the frequency of 0.1MHz, long press, reduce the frequency of 1MHz
K3: Short press, volume up(total volume 4 step), long press, display
K4: Short press, volume down(total volume 4 step), long press, restore factory settings, the frequency of 99 MHz, Volume step 3