1, + PLL,the frequency is more stable,the frequency not change with the environment to produce a frequency drift. 2,without any adjustment to bring the fun of DIY beginners. 3,the frequency can be continuously adjusted within a specified range. 4,with a microphone input and speaker volume can be controlled via digital potentiometer. 5,audio input volume can be adjusted via a digital potentiometer. 6, power can be adjusted continuously (non-linear) between the maximum power of 0.5W to 7W. 7, the power output is very good harmonic suppression network, the output spectrum cleaner 8, frequency and volume settings have power failure protection, you do not need to set boot! Now the transmitter to make a brief introduction: control panel components: mainly by M8 Series MCU and LCD display and keypad. transmitter board components: digital FM transmitter chip + 9018 + 2SC3355 + 2SC2851 + 2SC1971 four high frequency power amplification and power conditioning components. Input voltage: 12V DC the input current: approximately 1.0A the audio signal: Maximum input Vpp less than 1V microphone type: cylinder microphone or microphone power output: 0.5W-7W adjustable 6, the output impedance: 50Ω 7, the operating frequency: 76M-108MHz 8, frequency step: 0.1MHz 9, distortion: 0.03% to 0.1% a, board size: transmitting plate: 100 x 60mm, Dashboard: 55 x 36mm b, launch distance: more than 5KM (provided that the open area transmit antenna height above the surrounding buildings erected height of 10 times) c, stereo separation: more than 63db colour:blue Material:Metal+pc Package Contents: 1 * 7W FM stereo PLL FM transmitter 1 * Lcd Screen Only the above package content, other products are not included. Note: Light 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.