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Subelement L06a
Decibels.
Section L06a
A two-times increase in power results in a change of how many dB?
• 1 dB higher
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.

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How can you decrease your transmitter's power by 3 dB?
• Divide the original power by 4
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.

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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
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.

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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
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.

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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
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.

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The unit "decibel" is used to indicate:
• a single side band signal
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.

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

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

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

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

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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