Subscribe by email

TBA120 radio receiver for medium and long rf bands

Using TBA120 and some common electronic components ca be build a very simple radio receiver for medium and long rf bands.
Tuning stage of the TBA120 receiver also serves as active antenna that can be favorably positioned to get the best reception possible. Circuit is completely separate from the receiver, which consists of demodulator that provides audio-frequency output. Plastic case of the antenna input circuit contains a tuning coil designed on a ferrite bar (L2) and a double diode varicap. Antenna signal is transmitted to the tuning stage via a transistor (T1) repeatedly emitter ensuring a high impedance output signal to the modulator.
Received signal is amplified by the stage forming active antenna, but a part of the integrated circuit forming TBA120 modulator. L2 coil emitter serves as a shock to L3 disengages T1 and voltage supply agreement, and thereby prevents shorting the RF output signal of the active antenna. L4 does the same thing for the demodulator .
Potentiometer P2 T3's gain sets that provide a level of output signal compatible with the input necessary for any amplifier.
With the exception of L1, coils can be used for standard shocks coils. L1 consists of 250 turns of enamelled copper wire of 0.2 mm diameter, long-wave range, and 80 turns of enameled copper wire of 0.3 mm diameter (for medium waves) that is wrapped on a ferrite bar length about 20 cm and a diameter of 10 mm. Positive feedback loop is connected to an outlet of the coil located at one quarter the number of turns from the end of the ground.

Circuit Diagram: 
TBA120 radio receiver for medium and long rf bands circuit

Add new comment