Radio IF transformer (middle week) construction diagram and application matters

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The intermediate frequency transformer (commonly known as the middle week) is a unique transformer with a fixed resonant circuit in the superheterodyne transistor radio, but the resonant circuit can be fine-tuned within the inevitable limit, so that the resonant frequency can be achieved after the access circuit (465kHz). Fine tuning is accomplished by means of a change in the relative position of the core.

The intermediate frequency transformer in the radio is mostly single-tuned except for the night. The structure is simple and the space is small. Because the input and output impedance of the transistor is low, in order to make the intermediate frequency transformer match the input and output impedance of the transistor, the primary has the same secondary coupling coil with a small number of turns. The advantages of the dual tuning type are better selectivity and wider passband, which are often used in high-performance radios.

In the transistor radio, the two-stage intermediate frequency release switch is used in the daytime, so it is necessary to use three mid-weeks to perform the coupling and transmission of the flag of the front and rear. In the middle of the actual circuit, the BZ1, BZ2, and BZ3 symbols are commonly used to reveal the hints. In the scam, you can't change their position in the circuit at will.

The shape of the oscillating coil (medium wave) is similar to that of the mid-circle, and it and the responsive components form the inverter stage of the transistor radio. The isometric double connection (270pF×2) is used to adjust the resonant frequency of the input tuning loop and the local oscillator frequency of the local oscillator circuit. The envelope is within the limits of the receiving band: f-Δ_================================= Commonly used models are LTF-2-1 (primary 144+8.5袈溲, secondary tight. 5袈溲) and LTF-2-3 (primary 4.5+82匝, secondary 8匝).

Finally, let's talk about it: In the tuning, you should use the non-inductive tool to adjust as much as possible. Every time you adjust the magnetic cap of the IF transformer or the oscillating coil, do not pass the night. The force should be intentional to prevent the magnetic cap from breaking.