This article presents an amplifier to the antenna with a bandwidth of 80… 130 MHz. Its design is surprisingly simple, as his work. Especially good amplifier used in car radios.
The amplifier circuit diagram is shown in Figure 1.
The transistor T1 operates in a classic case with an external database, which is polarized by a resistor divider R1, R3. The signal from the antenna is supplied via a capacitor C1 to the emitter of T1, while the output capacitor is also connected to a coil T1. The elements have been chosen in such a way, to the amplifier side corresponded to the standard rod or a telescopic antenna, and output impedance – 75 ohm.
Coils L1 and L2 are such parameters:
- L1 – diameter of approximately 3 mm, 10 turns
- L2 – diameter 5 mm, 13 turns.