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9-1: Basic Principles of Signal Reproduction
Tuned Radio Frequency (TRF) Receiver
Many RF amplifiers use multiple tuned circuits.
Whenever resonant LC circuits tuned to the same frequency are cascaded, overall selectivity is improved.
The greater the number of tuned stages cascaded, the narrower the bandwidth and the steeper the skirts.
The main problem with TRF receivers is tracking the tuned circuits.
In a receiver, the tuned circuits must be made variable so that they can be set to the frequency of the desired signal.
Another problem with TRF receivers is that selectivity varies with frequency.