1. It uses STC8H1K17 microcontroller as the main control, built-in PLL local oscillator, built-in frequency indication circuit (using 7-segment digital tube, display unit is 10KHz, the photo has color difference, it is actually red), reception is divided into two bands (88-108 and 118-136), and stepping supports automatic . 2. The kit adopts TA2003 mixing + TA7613 medium/low-power solution, superheterodyne FM/AM receiver, one-time frequency conversion, intermediate frequency 10.7MHz. 3. Onboard digital volume potentiometer, supports automatic configuration saving, supports crystal oscillator frequency and receiving intermediate frequency adjustment. Tips: Since The VHF Band Is Similar To The Propagation Of Light-Straight Line Propagation, If The Receiving Location Is Barrier-Free But Far Away From The Airport ( 25Km), Please Be Sure To Install A High-Gain Antenna Such As A VHF Antenna; If There Are Large Obstacles Between The Receiving Location And The Airport (Including But Not Limited To High-Rise Buildings, Mountains, And Giant Towers), Please Avoid The Obstacles; Otherwise, You Can Only Receive One-Way Signals From Aircraft In, Thank You! Different Batches, Different Angles And Lighting, There Are Slight Differences Between The Actual Product And The Picture, Which Not Affect Normal Use (Delivered In Parts, Welding And Debugging Are Required By Yourself) Colour:Photo Color Material:PCB Package Contents: 1x R20 Shortwave Receiver DIY Kit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.