11-09-2013, 04:57 PM
RADIO TRANSMITTER AND RECEIVER
Tuned Circuit
Radios depends on the concept of tuned circuit
Tuned circuits are built from combinations of Inductors and Capacitors which have a self-resonant frequency.
Tuned circuits are thus able to selectively pass or block frequencies in transmitters and receivers.
They are the basis of tuners, filters, oscillators etc.
Transmitter
Transmitter concept is in the block diagram below:-
RF frequency generator generates a high frequency carrier signal.
Modulator modulates the input signal with carrier signal.
Operating Precautions
Ensure Transmitter frequencies/modes are setup correctly so emissions are always in Frequency bandwidth.
RF power amplifier outputs must be connected to a correctly matched antenna to work properly. Use of the wrong antenna can result in damage to the transmitter.
Excessive AM modulation or FM deviation will cause
distorted outputs.
Ensure that Microphone Gain (where fitted) is correctly adjusted