Rf Amplifier Circuit Am Radio

The rf amplifier is one of the key areas of any superheterodyne radio receiver and its performance can govern many aspects of the performance of the receiver as a whole.

Rf amplifier circuit am radio.

You can employ 1 4 watt resistors or even 1 2 watt resistors which are easier to manage. The amplified signals are fed to antenna input of the am radio receiver for better reception. The preamplifier circuit provides a gain higher than 10 in the lw and mw range. It is there to select the wanted frequency and reject some of the unwanted frequencies.

Trouble shooting an rf stage is fairly straight forward. 2 26 figure 2 19 is the schematic diagram of a typical rf amplifier that is used in an am radio receiver in figure 2 19 the input circuit is the antenna of the radio l1 a coil which forms part of an lc circuit which is tuned to the desired station by variable capacitor c1. Transistor rf amplifier circuit. The working of the circuit is simple.

The rf amplifier circuit and tuning is the first area of the radio receiver that the signal encounters when it enters the radio. Figure 2 19 is the schematic diagram of a typical rf amplifier that is used in an am radio receiver. There are no electrolytic capacitors and the three capacitors used can be ceramic or mylar. L1 is wound on the same core as l2 which couples the input signal through c2 to the transistor q1.

In the final part of this chapter you will be shown some typical rf amplifier circuits. Which makes the project simple and direct. It has about 25 db gain in the frequency rang 88 108 mhz. The amplifier works well when it is connected to the rest.

The circuit can also work for short wave sw range depending on the quality of practical implementation. The 10 meters 27mhz cw radio amplifier is equiped with vn66af transistor produced by siliconix wich has some blf245 fm 88 108 mhz rf amplifier p. Using a signal generator a modulated signal is applied to the antenna terminals and if the stage is working properly the amplified signal will appear in the plate circuit across the interstage transformer t 2 to be passed on the converter stage. Mirror frequency rejection is between 5 db to 9 db.

Noise figure is about 7 db at resonant frequency. However such a receiver need not have an transistor rf amplifier circuit following this tuned circuit. A radio receiver always has an rf section which is a tunable circuit connected to the antenna terminals.