Fangrui Product Details Specification: Name: Sdr Active Shortwave Antenna Amplifier Board Working Voltage: 6v ~ 15v Dc Frequency Range: 100khz-120mhz For Aviation And Frequency Modulation Bands. For Shortwave Signals, It Is 100khz ~ 30mhz. Gain: 0 ~ 400 (approximately 40db) Product Net Weight: 23.6g Size: 75mm X 35mm X 45mm Application: Sdr Radio, Shortwave Radio With External Antenna Port Note: 1. Requires One 9v 6f22 Battery For Power Supply; Switch Power Cannot Be Used Due To . The Antenna Cable And Sdr In The Photo Are For Reference Only. 2. Once You Have The Battery And Sm Cable, The Antenna Loop Is Ready. Insert The Other End Of The Sm Cable Into The Radios External Port Or The Sdr Receivers Input Port. 3. Turn On The Power And The Led Light Is Lit. 4. Toggle The Dx/local Gain Knob To Find The Effect Position: Clockwise For Greater Gain, Counterclockwise For Less Gain. Meanwhile, Adjust The Position Of The Loop Ring To Obtain A Better Signal. 5. The Antenna Is Only For Receiving Signals, Not For Emitting Signals. Co