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Subel. L06a
11 questions
Subelement L06a

Decibels.

Section L06a

A two-times increase in power results in a change of how many dB?

  • 1 dB higher
  • Correct Answer
    3 dB higher
  • 6 dB higher
  • 12 dB higher

GAINS in power: +3 dB = twice, +6 dB = four times (2x2), +9 dB = eight times (2x2x2), +10 dB = ten times, +20 dB = one hundred times (10x10), +30 dB = one thousand times (10x10x10). LOSSES: -3 dB = half, -6 dB = one quarter (0.5 x 0.5), -9 dB = one eighth (0.5 x 0.5 x 0.5), -10 dB = one tenth, -20 dB = one hundredth (0.1 x 0.1), -30 dB = one thousandth (0.1 x 0.1 x 0.1).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

How can you decrease your transmitter's power by 3 dB?

  • Divide the original power by 4
  • Correct Answer
    Divide the original power by 2
  • Divide the original power by 1.5
  • Divide the original power by 3

GAINS in power: +3 dB = twice, +6 dB = four times (2x2), +9 dB = eight times (2x2x2), +10 dB = ten times, +20 dB = one hundred times (10x10), +30 dB = one thousand times (10x10x10). LOSSES: -3 dB = half, -6 dB = one quarter (0.5 x 0.5), -9 dB = one eighth (0.5 x 0.5 x 0.5), -10 dB = one tenth, -20 dB = one hundredth (0.1 x 0.1), -30 dB = one thousandth (0.1 x 0.1 x 0.1).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

How can you increase your transmitter's power by 6 dB?

  • Multiply the original power by 3
  • Multiply the original power by 2
  • Multiply the original power by 1.5
  • Correct Answer
    Multiply the original power by 4

GAINS in power: +3 dB = twice, +6 dB = four times (2x2), +9 dB = eight times (2x2x2), +10 dB = ten times, +20 dB = one hundred times (10x10), +30 dB = one thousand times (10x10x10). LOSSES: -3 dB = half, -6 dB = one quarter (0.5 x 0.5), -9 dB = one eighth (0.5 x 0.5 x 0.5), -10 dB = one tenth, -20 dB = one hundredth (0.1 x 0.1), -30 dB = one thousandth (0.1 x 0.1 x 0.1).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

If a signal-strength report is "10 dB over S9", what should the report be if the transmitter power is reduced from 1500 watts to 150 watts?

  • S9 plus 3 dB
  • S9 minus 10 dB
  • S9 plus 5 dB
  • Correct Answer
    S9

A reduction at the transmitting station from 1500 watts to 150 watts is a drop of -10 dB (one tenth). The received signal strength which read '10 dB OVER Nine S units' will drop -10 dB to simply 'Nine S units'.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

If a signal-strength report is "20 dB over S9", what should the report be if the transmitter power is reduced from 1500 watts to 150 watts?

  • S9
  • Correct Answer
    S9 plus 10 dB
  • S9 plus 5 dB
  • S9 plus 3 dB

A reduction at the transmitting station from 1500 watts to 150 watts is a drop of -10 dB (one tenth). The received signal strength which reads '20 dB OVER Nine S units' will drop -10 dB to simply '10 dB over Nine S units'.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

The unit "decibel" is used to indicate:

  • certain radio waves
  • a single side band signal
  • Correct Answer
    a mathematical ratio
  • an oscilloscope wave form

The DECIBEL: "A unit used in the COMPARISON of two power levels relating to electrical signals". GAINS in power: +3 dB = twice, +6 dB = four times (2x2), +9 dB = eight times (2x2x2), +10 dB = ten times, +20 dB = one hundred times (10x10), +30 dB = one thousand times (10x10x10). LOSSES: -3 dB = half, -6 dB = one quarter (0.5 x 0.5), -9 dB = one eighth (0.5 x 0.5 x 0.5), -10 dB = one tenth, -20 dB = one hundredth (0.1 x 0.1), -30 dB = one thousandth (0.1 x 0.1 x 0.1).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

The power output from a transmitter increases from 1 watt to 2 watts. This is a dB increase of:

  • Correct Answer
    3
  • 30
  • 6
  • 1

GAINS in power: +3 dB = twice, +6 dB = four times (2x2), +9 dB = eight times (2x2x2), +10 dB = ten times, +20 dB = one hundred times (10x10), +30 dB = one thousand times (10x10x10). LOSSES: -3 dB = half, -6 dB = one quarter (0.5 x 0.5), -9 dB = one eighth (0.5 x 0.5 x 0.5), -10 dB = one tenth, -20 dB = one hundredth (0.1 x 0.1), -30 dB = one thousandth (0.1 x 0.1 x 0.1).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

The power of a transmitter is increased from 5 watts to 50 watts by a linear amplifier. The power gain, expressed in dB, is:

  • Correct Answer
    10 dB
  • 30 dB
  • 40 dB
  • 20 dB

GAINS in power: +3 dB = twice, +6 dB = four times (2x2), +9 dB = eight times (2x2x2), +10 dB = ten times, +20 dB = one hundred times (10x10), +30 dB = one thousand times (10x10x10). LOSSES: -3 dB = half, -6 dB = one quarter (0.5 x 0.5), -9 dB = one eighth (0.5 x 0.5 x 0.5), -10 dB = one tenth, -20 dB = one hundredth (0.1 x 0.1), -30 dB = one thousandth (0.1 x 0.1 x 0.1).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

You add a 9 dB gain amplifier to your 2 watt handheld. What is the power output of the combination?

  • 20 watts
  • 18 watts
  • Correct Answer
    16 watts
  • 11 watts

GAINS in power: +3 dB = twice, +6 dB = four times (2x2), +9 dB = eight times (2x2x2), +10 dB = ten times, +20 dB = one hundred times (10x10), +30 dB = one thousand times (10x10x10). LOSSES: -3 dB = half, -6 dB = one quarter (0.5 x 0.5), -9 dB = one eighth (0.5 x 0.5 x 0.5), -10 dB = one tenth, -20 dB = one hundredth (0.1 x 0.1), -30 dB = one thousandth (0.1 x 0.1 x 0.1).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

The power of a transmitter is increased from 2 watts to 8 watts. This is a power gain of __________ dB.

  • 8 dB
  • 9 dB
  • Correct Answer
    6 dB
  • 3 dB

GAINS in power: +3 dB = twice, +6 dB = four times (2x2), +9 dB = eight times (2x2x2), +10 dB = ten times, +20 dB = one hundred times (10x10), +30 dB = one thousand times (10x10x10). LOSSES: -3 dB = half, -6 dB = one quarter (0.5 x 0.5), -9 dB = one eighth (0.5 x 0.5 x 0.5), -10 dB = one tenth, -20 dB = one hundredth (0.1 x 0.1), -30 dB = one thousandth (0.1 x 0.1 x 0.1).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

A local amateur reports your 100W 2M simplex VHF transmission as 30 dB over S9. To reduce your signal to S9, you would reduce your power to ______ watts.

  • 33.3 W
  • Correct Answer
    100 mW
  • 1 W
  • 10 W

To bring a received signal strength of '30 dB OVER Nine S units' down to 'Nine S units' supposes a drop of -30 dB, i.e., one thousandth of the original power. In this example, 100 watts would need to be brought down to 0.1 watt.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

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