Five reasons why a homemade radio doesn't work well

In my previous article, I described how to make a very sensitive direct-conversion radio receiver. You can assemble the radio according to the circuit diagram, and when you turn it on, you might hear a loud whistle, clicks, and loud noise, but there will be no normal radio reception. Here I'll discuss five reasons why this might happen and how to fix them.These tips also apply to other radios.

1. Install the inductor coils perpendicularly. This will reduce the influence of the coils on each other, especially the oscillator coil and the input circuit.

If the coils are installed axially to each other, the influence between them will be maximum.

2. Avoid using long wires in the oscillator, otherwise these wires will begin to emit a strong signal that will reach the antenna and interfere with normal radio reception. It is advisable to shield the oscillator, and if there is no shield, as in my case, then move the receiving antenna via a coaxial cable away from the receiver.

3. Place a piece of aluminum or copper foil under the radio and solder the foil to ground. This may or may not improve the receiver's performance, but if the radio has high sensitivity, it's a good idea.

4. A major problem with low-frequency stages. Typically, whistling is caused by poor filtering of power supply noise and the appearance of various feedback. Install an RC filter on the power supply, and the whistling should disappear.

5. The last problem also concerns whistling or various audio distortions. Connect the power supply as close as possible to the largest current draw, which in a receiver is the low-frequency power amplifier. If you connect the power supply to stages that consume little current, distortion and interference may make it impossible to listen to radio stations.

I'll also add a few nuances when setting up a homemade radio receiver:

- Turn off all electronic devices near you, as they can generate strong interference.

- Make the ground wire and positive power wire thicker.

- Try using film capacitors between the low-frequency amplifier stages rather than oxide ones.