Author: Tu South
The application requires that it is used to receive the set of Asia 2 analog programs to receive regional stations in the Asian 3S Digital Program.
I want to use the simplest replacement receiver and high frequency head, retain the original pot (due to the original pot large, install a stable installation), but the site is available on the spot, the two meters of pots are installed in the United States production. The single output two-in-one high-frequency head (test, the performance is intact, as early as the first), because the fixed screw has been completely rusted, the high frequency head has not been taken at all (even if it is forcibly taken, the pot has No utilization value), and now popular receivers are used in conjunction with the bipolar single output high frequency head, and must be referred to the relevant information, and self-made an automatic polarized converter, serial in the digital and vintage high frequency. Between the head, the double-polarized program reception of automatic polarization conversion as the new high-frequency head is achieved, and the test effect is still more satisfactory.
Working principle: When the digital is receiving V vertical polarization program, the digital DC voltage is output to the high frequency header. The 18V DC voltage is output when the H-horizontal polarization program is received. Therefore, this voltage difference can be utilized to power the corresponding high frequency header, thereby controlling the working state of the high frequency head. The circuit is shown in the drawings.
Working process: When the vertical polarization program is to be received, the receiver output 14V left and right voltages is added to the converter. Since the average partial pressure of R1 and R2, the Q1 base voltage is about 7V, and the Q1 emitter is stabilized by D1 at 7.5V. Therefore, Q1 is closed, the Q1 collector is high at a high level of about 14V. After the R4 is added to the Q4 base, Q4 is closed, the horizontal polarization high frequency head is not working, and the Q1 collector 14V high level is added to R5 The Q2 base, the Q2 emitter is stabilized by D2 at about 9.1V, so the Q2 is turned on, the Q2 collector and Q3 base becomes low, Q3 is turned on, and the 14V voltage is powered by Q3 to the vertical polarization high frequency head. And start working, the Q3 of its signal is sent to the receiver.
When the horizontal polarization program is to be received, the receiver outputs 18V voltage. After R1, R2 averages, the Q1 base becomes about 9V, the emitter is still 7.5V, so the Q1 is turned on, the Q1 collector becomes 7.5V. The low level R5 is added to the Q2 base, and its emitter is still 9.1V, so the Q2 is closed, and Q3 is followed by cut off, and the vertical polarization high frequency head is stopped, while the Q1 collector is 7.5V low. The level is added to the Q4 base, Q4 is turned on, and the 18V voltage is added to the horizontal polarization high frequency head, and the signal is entered into the receiver through Q4. When the next 14V voltage is sent again, the q4 is closed, the horizontal polarization high frequency head is stopped, Q3 is turned on, and the vertical polarization high frequency head has started to work, so that the respective voltage is achieved. The corresponding high frequency head is reached, thereby completing the task of automatic polarization conversion.
Production: Use a two-dispenser to remove the components in the inside, only reserved the circuit board and socket, using the plate to weld the converter element to the plate, and then load it into the branch.
Debug: Accepted LNB header (can be used in advance using artificial conversion plug-in to complete the star and V, H signal download work) and receiver, from the actual situation, the vertical polarization program signal has no effect, However, the horizontal polarization program signal is reduced, and it can be found that a relatively weak platform (such as Phoenix TV), patient, slowly use the line of connection flying lines and components within the dispenser, so that the weak platform The signal quality becomes the maximum (close to the signal quality of the uncharged converter) to complete the debugging work.
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