Keywords: TDA7358, high frequency head, FM, radio
Author: gaogaoli ...
As the title, the grinding of radio frequency modulation systems such as 1103, DTS-09, RP2100, PL600 is a thing I have been loved in these years, helplessness, and the devices and device instruments are limited, and there is not much breakthrough. However, in the past year, due to the research of many good machines, such as Gude S700, I have browsed a lot of other information online, making my idea becoming more and more abundant. So today I will change the new idea to grind the electrical tuning machine of this type of TA7358 high frequency head. I believe everyone, especially a lot of seniors, I should think that I am very naive, you have already thought, but for me just love, the university specialist only learned to sweep the toilet, sweep the snow, hard work, how to endure, really The knowledge does not have anyone, it is still not easy, but I have a strong desire, and I am very patient. Oh, I haven't been can't do, I only can't think of it, it is that: How far is the thought, we can go! Ok, talk nonsense. Briefly introduce the process of grinding and grinding the effect! I have seen a lot of information and high frequency head design drawings. In fact, for high frequency reception, the most fundamental is to increase the Q value and reduce distortion. I have previously added a variety of field tube amplification before TA7358, but the effect is small, the root cause is that Q value is too low, and I have done it in the same time, but I can't do it, one is a power supply voltage. Low, another Q value is low, join several levels of high places, what to do with high places (except for electronics, I have not tried), the zoom is mixed with the lowest noise of the pipe, no more Large improvement. The signal availability is not as good as the high placed in the 7358 built-in, including the double gate tube, FM specialized field tube, ordinary three-pole is more similar, and their minimum signal pick-up ability is basically similar, noise coefficient There is no leap in the small point. Therefore, improve sensitivity first to improve the overall Q value. At the same time, reduce the distortion of the signals at all levels, or make the waveform pure.
The tuning of these machines is three, quad. However, it is a structure consisting of becompasion diodes and capacitors. Such a structural operation, the distortion of the waveform and the resulting medicine of the noise clutter is much higher than the LC circuit composed of the variable capacitors of the air. However, the inclusion diode is a general trend, a small size, convenient and power saving, although there are many shortcomings, but there are many advantages, and the advancement of science and technology is always double-sided, there is no perfect, only efforts to pursue perfection. Do you want to live for what? right? why? Instead, it is closest to air with a bipolar diode composition. Theory believes that such 5 can achieve the effect of the air quad. But I don't know why domestic manufacturers have no such structure. So how is this decisive effect? Is it really good? Oh, let's not watch the flicker! I have a picture, this picture is not the final drawing, but the difference is not big.
You can see that I have changed all three and four, and I have a backrest structure. At the same time, the connection between 7358 4-foot and harmonic loop, connected with the capacitance and the RF output of 3 feet, in fact, this is helpless After my trial, I can improve the sensitivity, then everyone says it is not to enhance the Q value? Yes, but due to the inconsistency of the current radio, combined with the internal circuit in the 7358, the low Q value of the low-resistance value will only reduce the sensitivity, and if its frequency and the frequency of 3 feet are deviated Good adjustment will make the overall sensitivity decline, in fact, if you design a high Q value but the inductance of the inductance and the first few levels, then I still feel that the inductance coupling is the best, this is also my next grinding idea. At the same time, the 33-pin signal is given to the antenna tuning loop, adding the incentive of point positive feedback. Then re-adjust each coil. For machines such as 1103,2100, don't use it without picking up, the 34-pin coil is still a oscillating source, improve the intensity of the signal, so the coil of the 3, 4 pin should be synchronously adjusted. After such improvements, the filter changed the filter MJ, and the medium release triode changed the BF840, adjusting T101, so that the intermediate frequency is more accurate. These basics are my thoughts. For DTS-09, the DTS-09 of the security, because the current machine only has double tuning, the change should be bigger, but there is a coil in the predecessor, so it is much more, remove the back capacitance, change The upper two becomes diodes, add 104 resistance, take the tuning voltage plus, and then re-input the signal to 1 foot, and the change is not large. The effect is a significant improvement in the four-unit machine than 1103, and the most obvious improves the sound quality! ! ! At the same time, absolute sensitivity is greatly improved. But it seems that there is a lack of one or a slightly inferior point. hehe. Look at the picture below
This is 1103. This is the DTS-09 this is that I pulled out the antenna in the room, I haven't fully pulled out, and I have received a small number, some have not listened to the name. Although there are still no stereo, you can at least you can listen to music and sound, and use the speaker to adjust the direction and you can listen very well. This is still a good meaning. 87.9 Beijing International Radio Station (I don't know where to broadcast the informed statement) 88.2? ? ? 88.6 What is Jiade 88.8? ? ? 89.0? ? ? 89.5 Global Chinese Radio Network 89.8 Announcement 968 Music FM 90.6 Zhangzhou Table 90.8 Anhui Traffic Music Table 91.4 Ningbo Economic Table 91.7 Zhejiang Hangzhou Taiwan 92.3? ? ? 92.6 Jiande 93.0 Zhejiang Transportation Taiwan 93.4 Shanghai People's Broadcasting Station 93.8 China Voice 94.2 Jinhua Transportation 94.8 Dragon Toy Tower 95.4 Lanxi Terrace 96.2 Zhejiang Taiwan 97.5 Cangzhou Transportation 99.1 Hangzhou 99.4 Hangzhou Table 99.8 Jinhuapu River Broadcasting Station 100.7 City Private Car Enjoy 968101.4 Jinhua Taiwan 101.7? ? 102.1? ? 103.0 Taiwan 103.3 Jinhua broadcast 103.7? ? ? 104.4 Jinhua News Table 104.7 Jiangshan Terrace 105.3 Zhangzhou News Table 106.2 Yiwu Tail 107.6 Chinese Voice Although there are several basic can't listen too clear, it has received it. As for Yiwu, Anhui Taitai, Anhui Terrace, 88.9, 99.1, 94.2, 92.6, etc., can enjoy the level. It's hard, I believe that if the next step is to increase the point Q value, can it make these Taiwan tables? In fact, there is also a transformer and a good way to improve Q value and place, you can be too difficult to achieve in such an environment. Oh, wait for the opportunity, I must do my own high-frequency head, do my own brand radio. I have to communicate welcome to my factory external hotline: 13157066203. By the way, the 7358 has changed the sound quality after the LA1186 is clearly warm. This is also a consistent feature of Sanyo's things. The dynamics and high frequency are high frequency than 7258, the signal-to-noise ratio is also high, but the absolute sensitivity is slightly reduced, it seems that 1186 should be used Need more strength.
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