V1.3 version finished product (white motherboard)

AMT-MW207 medium wave transmitter is a simple AM signal source suitable for amateur electronics enthusiasts and radio enthusiasts. It uses a magnetic rod to transmit electromagnetic waves without an external antenna. It can be used to test ordinary medium wave radios in places where the radio signal is insufficient. As well as ore radios, it can also be used as an instrument for debugging medium wave radios.

【Product name】Experimental medium wave (amplitude modulation) transmitter (Model_AMT-MW207)

【Main features of finished product】

1. Frequency range: 525~1605kHz

2. Power supply voltage: 6V

3. Circuit board size: 78mmx85mm (length × width)

4. Transmission distance: about 1 meter for superheterodyne medium wave radios, about 0.5 meters for direct and ore radios

【Features】

1. The circuit is simple. It is only composed of common triodes and resistance-capacitance inductive components, without audio transformers, which is easy to make;

2. The sound quality is good. Within the rated transmission distance, the sound quality is close to that of FM broadcasting, and the signal-to-noise ratio is good.

3. There is no need for an external antenna (tens of meters for medium wave), and the magnetic field leaked by the magnetic rod affects the receiver, which is easy to implement and the transmission distance is relatively short;

4. There are many interfaces, designed with waveform test terminals, audio sockets, external power sockets, etc., which are easy to use and expand functions;

5. It can be connected to an external power supply or installed with a battery for independent use.

【product description】

1. This kit adopts full discrete circuit, which is especially suitable for students to learn the working principle, practice production and test;

2. The variable capacitor uses a double-connected variable capacitor, and the two-connection parallel connection can obtain sufficient capacity;

3. Using double-sided circuit, the board base is glass fiber material, the thickness is measured about 1.5~1.6mm, the pad is sprayed with tin, and it can be directly welded without grinding;

4. This product has been revised for n times so far (mainly to modify the wiring of the circuit board and the circuit remains unchanged), and it is still in the process of continuous improvement. Usually minor and insubstantial modifications, such as slight movement of component positions and minor adjustments to wiring, will not change the version number, nor will they not be re-photographed and uploaded, hereby declare;

5. The manual contains circuit schematics and circuit board diagrams, as well as debugging methods and experience under amateur conditions. If more information and professional debugging methods are needed, please download or refer to relevant professional books online; mainly changes in component positions, circuit The structure remains unchanged.

6. The transmitter is equipped with a 3.5mm headphone signal cable, excluding batteries.

【Effect】

This transmitter works very well within the effective distance (0.5~1 meters), and the sound fidelity is high, especially when using direct radios (such as our 636 and 68-1 single-tube radios) with our self-made high resistance The sound quality is not much different from the direct playback effect of the player.

This product adopts a two-layer board stacking structure, and the bottom board is a battery power supply board

The battery board is equipped with 4 AA alkaline batteries. Due to the small power consumption of the circuit, the battery can be used for a long time.

Concise dial (currently subject to further revision)

On-board interface and control functions (v1.2r)

【Version Description】

The v1.3 version is modified from the v1.2 version, using a beautiful flat magnetic rod and adding a dial. The scale scheme comes from a radio using 223P variable capacitors. After inspection, there is a slight error. Players with high requirements can correct it with a digital display radio.