Posted by
Tom Hammond-3 on
Mar 30, 2005; 7:01pm
URL: http://elecraft.85.s1.nabble.com/OT-math-question-tp376370p376371.html
At 12:01 PM 3/30/05, you wrote:
>How would one calculate the amplifier gain (in dB) required to go from one
>power level to another? For example from 5W to 100W.
10 log(P2/P1) = 10 log(100/5) = 10 log(20) = 10 (1.30103) = 13.0103dB
An easy 'rule of thumb' way to get a good idea of such levels
is to remember that:
a power INcrease of 2 = approx. +3dB change
a power DEcrease of 2 = approx. -3dB change
a power INcrease of 10 = +10dB
a power DEcrease of 10 = -10dB
So, to go from 5W to 10W output, you have 3dB GAIN
to go from 10W to 100W, you have 10dB gain
Since dB's can be added, going from 5W to 100W = 3db + 10 dB = 13dB
Similarly, if you went from 2W to 800W...
From 2W to 4W (first doubling of power) = +3dB
From 4W to 8W (2nd doubling of power) = +3dB
From 8W to 800W (increase of 10X) = +10dB
-------
Total power increase in dB = +16dB
73,
Tom Hammond N0SS
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