Passive, source-free, mid-band transceiver device for use in a laboratory setting.
Nowadays, shortwave radio is less common than it used to be, and the interference from the environment is also greater. Listening to shortwave radio indoors, especially in remote areas away from radio stations, has become more difficult. I plan to build a DIY shortwave antenna amplifier to improve my reception. While I was idle, I collected relevant information online and gathered materials from around me. With minimal investment, I conducted a simple experiment. The results were quite satisfactory. Here's an introduction for those interested:
Figure 1: Exterior appearance
Figure 2, Dimensions for Fabrication:
Figure 3: Schematic diagram of the circuit and wiring.
A square frame made of one-meter long wooden strips. The coil is fixed using self-adhesive, non-stick pads (see diagram). There are approximately 20 wooden strips on each side, which are first glued to the wooden strip and then fixed when winding by passing the insulation wire through the corresponding square holes. Of course, you can also use other methods to fix the coil and prevent it from slipping.
Self-adhesive vinyl suction cup:
The resonant range of this device is: (560-1600 kHz, measured directly with a radio receiver)
Magnification factor: Cannot be determined
Effect: See video for details.
Instructions for use:
When listening to a Chinese radio station indoors, as long as you can receive the weak signal, bring the radio closer to this device and adjust it. Also, rotate the radio in the optimal direction (as determined by testing, which is perpendicular to the device), and the broadcast sound will be significantly amplified.
Experimental process video:
Bilibili video link
https://www.bilibili.com/video/BV1F14y1m7DC/?
https://www.bilibili.com/video/BV13s4y1F7vw/?
https://www.bilibili.com/video/BV1Vu411h784/?
The parameters in the figure are those I used; readers can adjust them according to their own circumstances.
Author: Lu Shen（BG8OBH）
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