[Yaesu] FT-1000(X) S-meter calibration

[VR97BrettGraham]

At 16:21 97.11.10 +0100, YT1ZKB asked:

>	Could someone please explain this ????
>It is my job to know things about dBu, dBm, uV, etc, but this conversion
>is totally unclear to me!
>
>Isn't it dBu = 20log(U/1uV) ?
>where:
>U is expressed in volts, 
>1uV is what it looks like it is:) and
>'log' is a base ten logarythm.
>
>So, 50uV/1uV = 50 -> 20log(50) = 33.979dBuV
>And +40dBuV would be:   10^(40dBuV/20)*(1uV) = 10^2 = 100uV
>If you write it down on paper it's much more clear.
>And for power it's dBmW = 10log(P/1mW)
>
>Hmm...unless you mean dBuW when you say dBu ? (which almost sure doesn't
>fit into my definition, too :)

I don't recall, but I think somebody had previously posted to 1000MP what
Yaesu calls a dBu - I think it was something other than a dBuV & then
somebody else then showed how this equates to something we can all relate to.

Quite simply, a dBu is a dBu, not a dBuV.  As well all know, a dB is an
expression of the relationship between two numbers.  In order to be
specific, it must to referred to something & if that reference is not
given, then one can only guess.

Personally, RF means power & power means watts, not volts.  At work, I even
go out of my way to talk watts, even when crossing over to a 75-ohm
environment where voltage seems to dominate, just to keep folks on their
toes (or to be obnoxious, according to some).

Now would anyone like to take a stab at why manufacturers give sensitivity
figures in voltage but noise floor, minimum discernable signal & others in
power?

73, VR97BrettGraham


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