Transmitter circuit to be discussed have a maximum power output of 200-250 mw. In order to transmit power to achieve maximum distance it is necessary to also adjust or the choice of a good antenna. Tuner's SWR with a good antenna will transmit power can achieve + / - 3 KM.
FM Transmitter Scheme has 3 main sections.
1. Modulator
2. Oscillator
3. RF power amplifiers
Modulator consists of a series of electrical Condenser the coupling's to collector T1 through R2 and C1 and C9
circuit formed by transistor T1 (BF494) is a low power amplifier that will generate variable frequency VHF spectrum oscillator area. D1 functions to generate a frequency modulation of the voice modulation. The output of this circuit Oscillator about 50 mW in Collector T1.
Transistor T2 functions as RF power amplifiers that will strengthen the power up to about 200 - 250 mw. T2 due to work as a class C amplifier is recommended to pair the heatsink (Cooler) is made of aluminum plate on the body T2.
hard look for transistors can be replaced just only
T1 = (FCS9018) circuit many oscillators in FM radio,
T2 = (2SC2053) is usually in the radio ICOM 2 meter mark
to minimize the outbreak of the frequency of recommended harmonization to provide protection in the form of a flat tin box on the circuit oscillator.
L1 - 4 wrap wire 20 SWG, wrapped in plastic sectional diameter of 8 mm.
L2 - 2 wrap wire 24 SWG, coiled coil L1 above.
L3 - 7 wrap wire 24 SWG wound in cross-section of air core diameter of 4 mm.
L4 - 7 wrap wire 24 SWG wound around the core Fada ferite and serves as a RFC (Choke)
VR1 serves to set the basic frequency.
VR2 serves to strengthen the power set.
VC1 and VC2 serves to align the maximum power from the transmitter (SWR).
Power Supply 12V, 2A is recommended to use a regulated PS circuit well. can also use the Battery or Battery.
to note not occasionally operate this circuit without supported with a good antenna that will damage the transistor T2.