Features: QRM elimination function: This product is designed specifically for broadcasting and television equipment, and can effectively eliminate QRM interference signals in the high frequency bands (1-30 MHz), improving reception quality. Built-in PTT control: The product has a built-in PTT (key transmission) control function, making it convenient for users to manually activate the elimination function when needed. Wide bands coverage: The product is suitable for the high frequency bands of 1-30 MHz and can be widely used in various wireless communication system and equipment, such as radios, television broadcasts, radio receivers, remote control equipment, etc. Efficient elimination: Professional QRM eliminators use advanced technology to efficiently reduce QRM interference signals and provide clear audioed and video transmission effects. Flexible control: The product adopts built-in PTT control, and users can flexibly activate and deactivate the elimination function according to their needs. Specifications: Material: Aluminum Housing+Epoxy Fiberglass Board FR4 Size: Approx. 125x110x51mm/4.92x4.33x2inch(excluding the connector part) Principle: The QRM eliminators is inserted into the antenna feed line from the TRX without the need for any other modifications to the radio. The box has a built-in PTT control that keeps the eliminators connected during transmission. However, additional auxiliary receiving antenna are required, such as a 200cm antenna or a few meter of wires in a shed. Two antenna received unwanted signals, resulting in different phases. The QRM canceller now allows for phase angle adjustment and amplification to cancel out unwanted signals before they reach the front end of the receiver! It is based on a completely innovative concept and cannot be compared to normal "muffler" performances. Note: There is an error of 0.5-1mm between the dial and the knob pointer. Package includes: 1x QRM Eliminators 1x PTT Cable 1x Antenna 1x Direct Current 2.1/5.5 Power Cord