6-Watt High-Power FM Transmitter (Driven by Car MP3 Player)
This versatile and high-performance FM transmitter circuit delivers up to 6 Watts of RF power. It uses a clever design: the low-power RF signal is sourced directly from a car MP3 player's built-in transmitter and then boosted through two robust RF amplification stages.
Essential Tuning Tools
When building any RF transmitter circuit, having the right test equipment is crucial for success and stability. You will need:
Frequency Counter: To accurately monitor your broadcast frequency.
RF Field Strength Meter (FSM): To tune for maximum output power. (Note: I have tested up to 3 different FSM circuit variants—photos are included below).
Circuit Stages & Transistor Lineup
First Stage (Driver): Uses the reliable 2SC2053 RF transistor. (Alternative: Any equivalent transistor capable of up to 500mW power delivery can be used).
Final Stage (Power Amplifier): Uses the 2SC1971 power RF transistor. (Alternative: Any equivalent high-frequency RF power transistor).
Thermal Management: A proper heat sink is strictly required for the final-stage 2SC1971 (a heat sink can also be used on the 2SC2053 for added stability).
Coil & Inductor Specifications
L3 Coil: 4 turns
L6 Coil: 12 turns
https://obaidkakar.blogspot.com/2019/10/fm-transmitter-25-watts-88-108-mhz.html
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