[Elecraft] dB conversions (was: Yaesu FT-2000 v K-3?)

[Brian Lloyd]

On May 11, 2007, at 9:57 AM, Sam Morgan wrote:

> lots of difference between
> 5w to 200w = 18+db

16dB

5x2=10 (+3dB)
10x2=20 (+3dB)
20x10=200 (+10dB)

> as compared to
> 100w to 1000w = 9+db

10dB

x2 = 3dB
x2.5 = 4dB
x4 = 6dB
x5 = 7dB
x8 = 9dB
x10 = 10dB

If you know that x2 = 3dB and x10 = 10dB you can do all of the above  
in your head in a second or two. I banged out x2, x4, and x8 (3dB,  
6dB, and 9dB) just like that. Then I worked backwards from x10. x5 is  
X10/2 or 10dB-3dB=7dB. If you want something in between one of these  
values you can just "split the difference" (interpolate). With this  
you can usually estimate any multiplier within 1dB without having to  
resort to a calculator.

73 de Brian, WB6RQN
Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com