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# Long Range FM Transmitter

2016-04-04 20:51
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## Building a Long Range FM Transmitter

Along range FM transmittercircuit below can be an option, especially for the beginner hobbyist FM transmitter. They usually begin to assemble an FM bug with approximately 100 mW of power, which only emit a signal around the house. With a little experimenting in building this transmitter will deliver about 5 watts of output power. Which of course will provide a range of the transmit signal farther than an FM bug.

This FM transmitter was built using a power transistor MRF237 final amplifier driven a buffer amplifier 2N4427 or 2N3866. An FET oscillator using a 2N4416 transistor to provide a stable output frequency of the FM broadcast band 88-108 MHz.

Audio modulation of the transmitter using a varactor diode (capacitive diode) MV2113, where the input sensitivity can be adjusted using a potentiometer 100K to give a clearer audio and clean. Limiting deviation is the 75us audio through a combination of R2C1.

### Long Range FM Transmitter Circuit

In thelong range FM transmittercircuit diagram, you can find the values ??of the components used. A suggestion for construction is that you can build the circuit blocks per step starting from the oscillator, buffer, and then final. On the oscillator, the configuration of L1 has 6 turns and tapped at 2.5 turns. You can experiment by turning the output frequency of the capacitor trimmer R5, or even for higher frequencies up to 150 MHz.

Long Range FM Transmitter Circuit Diagram

Once you have established a working frequency of the oscillator in the range 88-108 MHz, you can further build up the buffer that is at or 2n3866 2N4427 transistor. You can set the buffered output power is up to several hundred mW through a C9/C10 (R6 as a dummy load), where the output power level is used to drive the final amplifier. Of course in the output power of this tune you have to use a VHF power / SWR meter.

The next step is to complete the entire circuit in the final. Tuning is done using the C11/C12. Use of a dummy antenna load on the power / SWR meter to determine your maximum output power up to 5W. Then you can adjust the output impedance of the antenna.

To assemble the entire circuit can use the PCB upside down, so that a better grounding. You can create barriers to meeting the component lead and manage in such a way. Keep the component leads cut short as necessary. Alternatively, you can make a PCB, and then assemble the components.

Use a 12V regulated DC power supply, so that the transmitter signal is clean and free of noise. Good luck and happy experimenting with along range FM transmitter.