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Old July 19th 09, 08:43 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Jun 2006
Posts: 147
Default dB relation TX/RX

In article ,
Ian Jackson wrote:

In message , Roy Lewallen
writes
Sal M. Onella wrote:
I've heard the same thing, but the reality is that the S-meter
usually
follows the AGC and the signal for S9 could be different for every design.
But Flex radio and others define S9 as 50 uV. . .


Adjusting the S-meter to read a specific value for one signal strength
is simple, and there's often an adjustment for doing it. I think it's
fairly common to find S9 to be around 50 uV -- on one band at least --
although I wouldn't be surprised to see a fair amount of variation from
band to band. But that has nothing to do with what the difference is
between S7 and S8, S8 and S9, etc.

Isn't there a school of thought which says that, above 1000MHz, an
S-point is 3dB? [Don't ask me why!]


there are "Many Schools of thought".... but unless someone rewrites the
Laws of Physics, and increase in Tx Output will show and Increase of Rx
Input, on the same path, period. S-meters are NOT necessarily actually
showing Rx Receive Signal Strength, and they are rarely, either linear,
or even Logrythmnic in presentation of what they do represent. In the
Microwave Field if you measure a path, and also calculate that path,
comparing the two will show that they are very close, if you did it
right....