Figure 3 shows the FM transmitter building in a housing area of about 300-500 meters away from the actual launch, when the FM transmitting station as a small area (such as the campus radio, etc.) the launch of 1-3 km from the general requirements, which further increase of transmission on the RF transmitter output power, RF output power as MEC002A large, can directly stimulate C RF power amplifier circuit, and C RF power amplifier circuit of Gongzuo higher efficiency and thus increase the level just Zai constituted by the C1971 C RF power amplifier circuit can effectively increase their firing range 1-3 km, MEC002A power extended circuit shown in Figure 4, the RF signal transmitted by the coupling to the RF power control circuit of base C1971 , amplified RF signal by filtering the air emitted from the antenna, Figure 4 C RF power amplifier circuit input and output coupling circuits resonant at 79MHz, MEC002A model selected center frequency at 79MHz 2MHz can be about, such as MEC002A12V80MHz, transmitting antenna can be used 1.2-1.5 m rod antenna or outdoor antenna, when using an outdoor antenna away from launching its role in the open area up to 3 km. The circuit only uses two circuitry amount to over a kilometer away from the launch to make production of the long-range FM transmitter becomes very easy, just after the general assembly of fine-tuning its resonant coupling circuit input and output audio module in the center frequency for. Overall circuit power consumption of about 300mA or so, power is best used with three 6V batteries in series motorcycle, if the use of electricity power supply, voltage regulator and filter should be sure to do the circuit, otherwise it will interfere with the introduction of hum or degrade the circuit not work properly. C, the FM Stereo Transmitter remote: Figure 5 is in Figure 4, based on the increased level posed by the BA1404 FM stereo encoder circuit, so that Figure 4 from single-channel transmitter upgrade to mono, stereo dual-use FM transmitter, where the internal abandon BA1404 The front audio amplifier, radio frequency oscillator circuit and RF amplifier circuits need not only use its internal stereo coding part of the circuit, 19KHz pilot signal and the stereo composite signal by BA1404 of 13-14 feet out, and sent to MEC002A of modulation port AI, on the internal high-frequency oscillation source module FM. This machine is suitable for use as a school or unit of FM stereo radio station. Introduces several launches over 3 kilometers away from the FM transmitter, who wish to further increase the transmission power, and the C1971 can MEC002A to add one from the C2053 between the composition of the RF buffer amplifier, to improve the C1971 one of the RF excitation power, thus increasing to 3-5 km from the launch, the buffer amplifier input and output coupling circuits and the C1971 a similar, readers can design their own, I will not elaborate, the work of the current control circuit in about 500-800mA .