VHF section 0.5W TV transmit circuit ----- 0.5W TV Transmitter

VHF section 0.5W TV transmit circuit, 0.5W TV Transmitter Keywords: TV transmitter, transmit circuit, TV transmitting circuit, transmitter production, UPC1507 The television transmitter, the audio output from the satellite television receiver, VCD, recorder, etc., the video signal is transmitted in an open mode, and the signal is received with an outdoor antenna. Suitable for units, schools, factory mines, etc., when used in the use of a folded vibrator antenna, cover the distance. 1882.800 meters. The whole machine circuit is shown in Figure 1. IC1 is a TV radio modulator dedicated circuit, and the SAW vibrator of the same frequency is selected, and the audio and video signal can be modulated into the RF signal of the TV1 to 12 channels. The RF (RF) signal output by the IC1 is filtered out of the filter network A1 (see Fig. 2), and after the C15 is coupled to the radio frequency power amplifying circuit, the C15 is enlarged. SAW vibrator is a visual surface wave oscillator that is comparable to crystal. Although the frequency stability coefficient is more than crystal oscillator, it has a frequency of characteristics, and does not generate the advantages of secondary waves, such as selecting 5 channels. SAW oscillator, does not need to adjust the μPC1507 to output the RF signal of the 5 channel. This machine is 5 channel SAW vibrators, since the TV5 sound is within 87 to 108 MHz band, therefore, the frequency modulated radio is used as a program listener. The power supply is an important part of the transmitter. If performance is poor, it will seriously affect the sound quality of the listening. The transmitter is powered by a 12V supply transformer with a 12V supply of about 10W, and filters 7806, 7818, and supplies power to the VA and VB. It is worth noting that diode bridge full-wave rectification must be used, otherwise the quality of listening will may be interfered with communication. The inductor coil L2 ~ L6 is wound on the  3mm ballpoint brush wire in the  3mm ballpoint pen, L2, L6 is 4T, L3, and the data is 4T, and the number of supercles is 5 channels, if other channels, A1 The L, C value of the network must be replaced; L1 uses 01mm enamel line, wound 27T on the Siki frame of the TV medium, adjust the magnetic core to be fine-tuning the electricity; L7, L8 with 09mm enameled wire in  5mm The round rod is formed around 9T; the inductance of the inductance L1 is an air core coil. ANT is a half-wavely converted vibrator antenna, connecting with a cable TV 75Ω cable, the cable length between the antenna between the transmitter is not more than 15 meters. When debugging, the appropriate-dial of the inductance allows the image to achieve the best state. Be Click here to look at the large image

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