FM transmitter circuit in the figure below is an FM transmitter that comes with the VCO and the transmitter power transistor 2SC1971. FM transmitter with a VCO circuit in the following figures have been equipped with a power supply circuit transistor and ready to be assembled in the PCB. FM transmitter circuit uses technology VCO (Voltage Control Oscillator) to determine the operating frequency of the FM transmitter circuit. Working frequency circuit FM transmitter with transistor 2SC1971 and VCO, it can be set at the frequency range 88 MHz to 108 MHz. The main circuit VCO FM transmitter is diode varaktor. This FM transmitter circuits can be directly input audio signal from the output of tone control or the front audio output amplifier (pre amp). This FM transmitter circuit using a transmitter power transistor 2SC1971 and has a 10 Watt transmit power. A complete range of components and a list of FM transmitter 2SC1971 + VCO can be seen in the following figure.
FM Transmitter Circuit With 2SC1971 And VCO
VCO circuit for FM transmitters on the configuration of the voltage divider circuit 470 Ohm resistor, VR 5 kOhm with varaktor diode. VCO circuit is set varaktor diode capacitance values as a series tank circuit at the transmitter oscillator circuit.
Oscillator and mixer circuits into one and use the amplifier transistor 2SC829. Oscillator operating frequency is determined by the capacitance diode varaktor the VCO circuit. So that the operating frequency circuit can be set using the VR 5 Kohm on the VCO. In this section also functions as a mixer between audio signal and the carrier frequency (carrier) of the oscillator.
This initial amplifier circuit using a transistor 2SC829 and serves to strengthen the signal as an input to the driver circuit to power the transmitter circuit. FM transmitter driver circuit is built in a terraced row of transistor 2SC2053 and 2SC1970 transistors.
Transmitter power circuit or final circuit is often called the FM transmitter uses power transistor 2SC1971 and able gave the FM transmit power of 10 Watt.
On the driver and final Fm transmitter is equipped with a trimer that functions to regulate the accuracy of the impedance (matching) between each part in order to obtain maximum power absorption in each section to be transmitted to the antenna. Trimer arrangement shall be made to avoid the leakage jets. The FM transmitter circuit with 2SC1971 and VCO can be described in the following sections.