Features: 21MHz crystal main oscillator+Class C high-frequency amplification. With a volume adjustment knob, it can be connected to an external sound source input and a 9V power input (from left to right). A high potential red modulation voltage converter can superimpose TA7368 audioed power onto direct current. On-board fuses will not burn out the power transistors due to excessive current in Class C amplifiers. Comes with a 60cm stretchable antenna, which can be clearly received within 10meters. Suitable for various campus broadcasting and small-scale communication needs, such as broadcasting campus information, broadcasting songs, organizing activities, outdoor activities, wilderness exploration, camping and other communication needs. Specifications: Material: Printed Circuit Board Power Supply: Voltage Direct Current Power Supply 9V2A; The Whole Current 50 to 80mA Frequency: 21MHZ Crystal Frequency Stabilization Adjustment Amplitudes: 45% High Frequency Power: 100mW Modulation: Transform High Potential Modulation Sound Source: External Connection Sound Source, Phones, MP3, Computers, etc Available Transmitting Distance: more than 10m/32.8ft Production Difficulty: Welding, no need Debugging Applicable: Radio Enthusiasts, Students Experimental Testing Package Includes: 1x Short Waved Low-power Radio Transmitter Board(Finished Board) 1x Antenna 1x Connection Line 1x User Manual note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.