Video (AV) Reveter Frequency (RF) Converter ----- AV TO RF Converter

First, the circuit principle converter circuit is shown in Figure 1. Q1, C1, C2, C3, C4, L1 constitute a deformable parallel capacitor three-point oscillator (also known as tile oscillator), generating an image carrier frequency signal of 38.625 MHz, and then coupled to the B pole of Q2. Q2 On the one hand, the 38.625 MHz signal multiplier, generates 77.25 MHz image carrier frequency signals falling at the four channel; the other party is modulated to modulate the 6.5 MHz frequency band audio signal generated by Q3, generate 83.75 MHz sound carrier frequency signal, and These two carrier frequency signals are output by C9 after mixing. The image signal is added to the E pole of Q2 by C16, VRL. Figure 1 AV-RF converter Second, the component selection L1 with φ0.5 mm enameled wire on the ring of φ0.5 mm around 15, L2 with φ0.5 mm enamel line on the 5 mm round wooden rod around 8, at 4 Tap, B1 is converted in a black and white TV. With the φ0.1 mm of the enamel wire with φ0.1 mm, the φ0.1 mm is used, and the 6 turns is graded. Q1-Q3 is selected with B>30, FT>600MHz 3DG80, S9018 triode, other component resistance, capacity, as shown in Table 1. Third, after the production and debugging, after the component is installed, the VR1 is adjusted in the middle position, plus the power supply, the voltage is about 10 mA, when the shorts of Q1, Q2 are pole, and the current should be there. Variety. Put the RF plug on the TV antenna jack, pick up the tone / video signal, adjust the turns between L1 and L2 with insulator, so that the radio frequency signal is the strongest; if the sound is not clear, the B1 core is fine, and finally adjusted VR1 makes the image chrominance and brightness. Since the converter has a high operating frequency, it is easy to interfere, it is best to seal it with a metal (such as the easy pull can) (pay attention to insulation). The power supply circuit is shown in Figure 2. 9V AC can be taken from the TV.

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