HAM Radio Extra Class MCQ 5

Question 1

What is the maximum symbol rate permitted for RTTY or data emissions in the 80-meter amateur band below 3600 kHz?

Accepted Answer

300 baud

Answer

FCC Part 97.307 limits the symbol rate to 300 baud for RTTY and data emissions below 28 MHz (including 80 meters).

Question 2

A buffer amplifier is placed between a VFO and subsequent amplifier stages primarily to:

Accepted Answer

Isolate the oscillator from load variations that could cause frequency pulling

Answer

Buffer amplifiers present a constant, high-impedance load to the oscillator, preventing output loading from shifting the oscillation frequency.

Question 3

What phenomenon causes a received signal to vary rapidly in strength and phase when the receiving antenna is moved only a fraction of a wavelength?

Accepted Answer

Multipath fading due to constructive and destructive interference of reflected waves

Answer

Multipath fading occurs when multiple reflected signal paths arrive with different delays, causing phase differences that alternately add or cancel.

Question 4

Which parameter best describes the ability of a receiver to reject an interfering signal on an adjacent channel?

Accepted Answer

Selectivity

Answer

Selectivity describes how well a receiver attenuates signals outside its passband, determining adjacent-channel rejection.

Question 5

What is a 'Doherty amplifier' and why is it used in modern RF transmitters?

Accepted Answer

An efficiency-enhancing amplifier topology that keeps efficiency high across a wide range of output power levels

Answer

The Doherty architecture uses a carrier and peaking amplifier to maintain high efficiency (close to Class B) even at power back-off levels typical of modulated signals.

HAM - Radio Extra Class Test Practice Test

HAM - Radio Extra Class Test Practice Test

HAM Radio Extra Class MCQ 5