2 Watts FM transmitter

This is a nice 2 Watts FM transmitter. It has a Super-Sensitive pre-amplification with BC109 and BC177 with more than 100% signal modulation. The job finish the 2N2219 by Motorola. For the Coils you should use 1mm wire(enameled), L1= 3 turns - 10mm diameter, L2= 1 turn - 10mm diameter. R9 trimmer controls the modulation gain. The tunning is easy by controlling C9 trimmer (88-108 MHz). The RFC J should be the VK220J with ferrite (VK200 is not suitable). You will be amazed how well this little monster can transmit several kilometers excellent quality sound. Feed input from a simple cd player or PC (win amp) or just connect a microphone. Enjoy!

The described FM transmitter operates at a power output of 2 Watts, making it suitable for personal broadcasting applications. The design incorporates a sensitive pre-amplification stage utilizing the BC109 and BC177 transistors, which enhance the input signal and facilitate over 100% modulation depth. This capability is crucial for achieving high-quality audio transmission.

The final amplification stage is handled by the 2N2219 transistor from Motorola, which is known for its robustness and efficiency in RF applications. The circuit design includes two inductors, L1 and L2, which are essential for tuning the transmitter's output frequency. L1 is constructed with three turns of 1mm enameled wire wound around a 10mm diameter form, while L2 consists of a single turn of the same wire and diameter. The choice of wire gauge and the number of turns directly influence the inductance and, consequently, the tuning range of the transmitter.

Modulation gain is adjustable via the R9 trimmer potentiometer, allowing for fine-tuning of the audio input signal before it is transmitted. This feature is particularly useful for accommodating different audio sources, such as CD players, personal computers, or microphones. The tuning of the transmitter is accomplished through the C9 trimmer capacitor, which allows adjustment of the operating frequency within the FM broadcast band, specifically from 88 MHz to 108 MHz.

An important consideration in the design is the selection of the RFC J inductor, which should be the VK220J model with ferrite material. The VK200 variant is noted as unsuitable, likely due to differences in inductance characteristics that could affect performance.

Overall, this FM transmitter design is capable of delivering excellent sound quality over several kilometers, making it a versatile choice for hobbyists and enthusiasts interested in personal broadcasting. The simplicity of the circuit allows for easy assembly and operation, providing an enjoyable experience for users looking to experiment with FM transmission.This is a nice 2 Watts FM transmitter. It has a Super-Sensitive pre-amplification with BC109 and BC177 with more than 100% signal modulation. The job finish the 2N2219 by Motorola. For the Coils you should use 1mm wire(enameled), L1= 3 turns - 10mm diameter, L2= 1 turn - 10mm diameter.

R9 trimmer controls the modulation gain. The tunning is easy by controlling C9 trimmer (88-108 MHz). The RFC J should be the VK220J with ferrite (VK200 is not suitable).

You will be amazed how well this little monster can transmit several kilometers excellent quality sound. Feed input from a simple cd player or PC (win amp) or just connect a microphone. Enjoy!