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Subelement F
Receivers
Section 44
Mixers
What is the image frequency if the normal channel is 151.000 MHz, the IF is operating at 11.000 MHz, and the LO is at 140.000 MHz?
  • 131.000 MHz.
  • Correct Answer
    129.000 MHz.
  • 162.000 MHz.
  • 150.000 MHz.

What is the image frequency if the normal channel is
151.000 MHz, the IF is operating at
11.000 MHz, and the LO is at
140.000 MHz?

129.000 MHz.

\[140 - 11 = 129\]

Please see the Electronics Notes site for the article Radio Receiver Image Rejection

See Wikipedia's article Image response

Also, see the Radar Tutorial Eu site for the article Image-Frequency Interferences

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What is the mixing process in a radio receiver?
  • The elimination of noise in a wideband receiver by phase comparison.
  • The elimination of noise in a wideband receiver by phase differentiation.
  • Distortion caused by auroral propagation.
  • Correct Answer
    The combination of two signals to produce sum and difference frequencies.

What is the mixing process in a radio receiver?

The combination of two signals to produce sum and difference frequencies.

The mixing process facilitates tuning to a group of frequencies in a band, and producing the desired frequency. There are generally either active or passive mixers. The mixing of radio frequencies produces a new frequency from the multiplier combination of the signals, as stated in the answer.

See Wikipedia's article on Radio receiver and the article on Frequency mixer

Also, see the Electronics Notes site for the article on RF Mixing / Multiplication: Frequency Mixers

And, see the Digi-Key Electronics site for the article on Understanding the Mixer’s Role in an RF-receiver Design*

For more information, please see the RF Wireless World site for the article RF Mixer basics tutorial

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In what radio stage is the image frequency normally rejected?
  • Correct Answer
    RF.
  • IF.
  • LO.
  • Detector.

In what radio stage is the image frequency normally rejected?

RF.

Please see the Electronics Notes site for the article Radio Receiver Image Rejection

See Wikipedia's article Image response

Also, see the Radar Tutorial Eu site for the article Image-Frequency Interferences

Last edited by markadlerdallas. Register to edit

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What are the principal frequencies that appear at the output of a mixer circuit?
  • Two and four times the original frequency.
  • The sum, difference and square root of the input frequencies.
  • Correct Answer
    The original frequencies and the sum and difference frequencies.
  • 1.414 and 0.707 times the input frequency.

What are the principal frequencies that appear at the output of a mixer circuit?

The original frequencies and the sum and difference frequencies.

The mixing process facilitates tuning to a group of frequencies in a band, and producing the desired frequency. There are generally either active or passive mixers. The mixing of radio frequencies produces a new frequency from the multiplier combination of the signals, as stated in the answer.

See Wikipedia's article on Radio receiver and the article on Frequency mixer

Also, see the Electronics Notes site for the article on RF Mixing / Multiplication: Frequency Mixers

And, see the Digi-Key Electronics site for the article on Understanding the Mixer’s Role in an RF-receiver Design*

For more information, please see the RF Wireless World site for the article RF Mixer basics tutorial

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If a receiver mixes a 13.8 MHz VFO with a 14.255 MHz receive signal to produce a 455 kHz intermediate frequency signal, what type of interference will a 13.345 MHz signal produce in the receiver?
  • Local oscillator interference.
  • Correct Answer
    An image response.
  • Mixer interference.
  • Intermediate frequency interference.

If a receiver mixes a
13.8 MHz VFO with a
14.255 MHz receive signal to produce a
455 kHz intermediate frequency signal, what type of interference will a
13.345 MHz signal produce in the receiver?

An image response.

HINT: 13.345 also produces 455kHz IF when mixed with 13.8 MHz

Please see the Electronics Notes site for the article Radio Receiver Image Rejection

See Wikipedia's article Image response

Also, see the Radar Tutorial Eu site for the article Image-Frequency Interferences

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What might occur in a receiver if excessive amounts of signal energy overdrive the mixer circuit?
  • Automatic limiting occurs.
  • Mixer blanking occurs.
  • Correct Answer
    Spurious mixer products are generated.
  • The mixer circuit becomes unstable and drifts.

What might occur in a receiver if excessive amounts of signal energy overdrive the mixer circuit?

Spurious mixer products are generated.

See Wikipedia's article on Radio receiver and the article on Frequency mixer

Also, see the Electronics Notes site for the article on RF Mixing / Multiplication: Frequency Mixers

And, see the Digi-Key Electronics site for the article on Understanding the Mixer’s Role in an RF-receiver Design*

For more information, please see the RF Wireless World site for the article RF Mixer basics tutorial

Last edited by markadlerdallas. Register to edit

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