It has long been believed that manufacturing and tuning a superheterodyne receiver is impossible without special equipment. However, modern radio components have made the construction of such a receiver available to everyone.
Instructions
Step 1
Purchase a dedicated micro-assembly brand KXA058. It is a printed circuit board on which several SMD components are installed, as well as an unpackaged version of the well-known K174XA42 microcircuit.
Step 2
Rotate the microassembly so that the printed circuit board on its substrate is facing you and the leads are facing down. The first pin will be on the left. In total, the microassembly has 19 pins.
Step 3
Connect a 50 ohm resistor (not kilo-ohm!) Between pins 7 and 9.
Step 4
Pins 11, 12, 13 and 14 connect together and connect to the common wire.
Step 5
Connect an antenna to pin 8 through a capacitor with a capacity of about 100 picofarads (be sure to indoor, so that lightning protection is not required).
Step 6
Connect pins 1, 4 and 16 of the microassembly together. Between the point of their connection and pin 2, connect a frameless coil with a diameter of about 4 millimeters, which has several turns.
Step 7
Take a variable capacitor from a faulty VHF unit (a normal one, intended for use in medium-wave receivers, will not work). Connect it between microassembly pins numbered 2 and 3.
Step 8
Connect a capacitor with a capacity of 0.01 μF between terminal 15 and the common wire. Also, to pin 15, connect the positive plate of an electrolytic capacitor with a capacity of 10 μF, designed for a voltage of 16 V. From its negative plate, apply an active signal to the computer speakers.
Step 9
Apply a positive supply voltage of several volts to pin 18 of the microassembly.
Step 10
Turn on your speakers and power supply. Adjust the volume on your speakers. Place the variable capacitor in the middle position. Changing the number of turns of the coil (turning off the power before each soldering), as well as stretching and compressing its turns, try to find a section of the range in which there are radio stations. Then fill the coil with paraffin, and select the station of interest with a variable capacitor.
