Key Topic 48: Detectors

Question 1

3-48F1: What is a product detector?

A. It provides local oscillations for input to the mixer.
B. It amplifies and narrows the band-pass frequencies.
C. It uses a mixing process with a locally generated carrier.
D. It is used to detect cross-modulation products.

Answer 1

C. It uses a mixing process with a locally generated carrier.

Question 2

3-48F2: Which circuit is used to detect FM-phone signals?

A. Balanced modulator.
B. Frequency discriminator.
C. Product detector.
D. Phase splitter.

Answer 2

B. Frequency discriminator.

Question 3

3-48F3: What is the process of detection in a radio diode detector circuit?

A. Breakdown of the Zener voltage.
B. Mixing with noise in the transition region of the diode.
C. Rectification and filtering of RF.
D. The change of reactance in the diode with respect to frequency.

Answer 3

C. Rectification and filtering of RF.

Question 4

3-48F4: What is a frequency discriminator in a radio receiver?

A. A circuit for detecting FM signals.
B. A circuit for filtering two closely adjacent signals.
C. An automatic band switching circuit.
D. An FM generator.

Answer 4

A. A circuit for detecting FM signals.

Question 5

3-48F5: In a CTCSS controlled FM receiver, the CTCSS tone is filtered out after the:

A. IF stage but before the mixer.
B. Mixer but before the IF.
C. IF but before the discriminator.
D. Discriminator but before the audio section.

Answer 5

D. Discriminator but before the audio section.

Question 6

3-48F6: What is the definition of detection in a radio receiver?

A. The process of masking out the intelligence on a received carrier to make an S-meter operational.
B. The recovery of intelligence from the modulated RF signal.
C. The modulation of a carrier.
D. The mixing of noise with the received signal.

Answer 6

B. The recovery of intelligence from the modulated RF signal.