Rf Amplifier Circuit Am Radio

Which makes the project simple and direct.

Rf amplifier circuit am radio. 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. The rf amplifier circuit and tuning is the first area of the radio receiver that the signal encounters when it enters the 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. The preamplifier circuit provides a gain higher than 10 in the lw and mw range.

The working of the circuit is simple. The amplifier works well when it is connected to the rest. However such a receiver need not have an transistor rf amplifier circuit following this tuned circuit. The circuit can also work for short wave sw range depending on the quality of practical implementation.

Trouble shooting an rf stage is fairly straight forward. Figure 2 19 is the schematic diagram of a typical rf amplifier that is used in an am radio receiver. Mirror frequency rejection is between 5 db to 9 db. 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.

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. There are no electrolytic capacitors and the three capacitors used can be ceramic or mylar. Transistor rf amplifier circuit. L1 is wound on the same core as l2 which couples the input signal through c2 to the transistor q1.

The particular circuit configuration used for an rf amplifier will depend upon how that amplifier is used. Noise figure is about 7 db at resonant frequency. It has about 25 db gain in the frequency rang 88 108 mhz. Am fm radio frequency amplifier this am fm radio frequency amplifier is built with only a few components.

In the final part of this chapter you will be shown some typical rf amplifier circuits. An input amplifier for a fm radio receiver with rf selection 88 108 mhz has been designed in the radio project. It is there to select the wanted frequency and reject some of the unwanted frequencies.