1. The document discusses different types of AM radio receivers in their historical order: crystal receivers, tuner radio frequency (TRF) receivers, and superheterodyne receivers. 2. TRF receivers are described as containing 5 basic components: antenna, one or more tuned radio frequency amplifier stages, detector, optional audio amplifier, and they amplify the desired radio signal while rejecting others. 3. The advantages of TRF receivers are their simplicity and high sensitivity, while the disadvantages include instability, poor audio quality, and difficulty designing for higher frequencies.

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jhonvicker22@gmail.com Waqar Ahmed

2.  Classification of AM Radio Receivers…
 Crystal & TRF Receivers…
 Merits & Demerits…
 Receiver Parameters…
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3.  The classification is based on the age-
wise development of radio receiver.
1. Crystal Receiver
2. TRF Receiver
3. Super heterodyne Receiver
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4.  It contains four basic
components
1. Antenna or Aerial
2. Tuned circuit
3. Detector (diode)
4. Output device (head/earphone)
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7.  Easy to assemble to
receive local radio
station.
 No DC power is
required for this.
 Use as a DC power
source for another
amplifier receiver.
 Instability.
 Insufficient adjacent-
frequency rejection.
 It has poor audio
quality.
 It needs a high roof
tip aerial of about 20
feet height.
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8.  “tuned radio frequency receiver”
 It consists of five basic components…
1. Antenna or Aerial
2. One or more TRF Amplifier stages
3. Detector (diode)
4. Usually an audio amplifier
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10.  One or more tuned RF amplifier stages. These amplify
the signal of the desired station to a level sufficient to
drive the detector, while rejecting all other signals
picked up by the antenna.
 A detector, which extracts the audio (modulation)
signal from the radio carrier signal by rectifying it.
 Optionally, but almost always included, one or
more audio amplifier stages which increase the power
of the audio signal.
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11.  TRF receivers are
simple to design.
 TRF has high
sensitivity.
 ability to drive the
speaker to an
acceptable level (to
amplify)
 It allow the
broadcast frequency
535 KHz to 1640
KHz. But at the
higher frequency, it
produces difficulty
in design.
 Problem of
instability.
 It has poor audio
quality.
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12.  Selectivity
 Sensitivity
 Fidelity
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13.  Selectivity of radio receiver is its ability to
accept a given band of frequencies & reject
unwanted signals.
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14.  Ability to amplify weak signals. Broadcast
receivers / radio receivers should have reasonably
high sensitivity.
 A measure of the ability of the receiver to
produce, at the output of the receiver, an exact
replica of the original source information.
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Fidelity

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