db relation TX/RX
 

"Sal M. Onella" wrote in message
...

"Owen Duffy" wrote in message
...
"Sal M. Onella" wrote in
:

...
Chart values do decrease at 6 dB per S-unit but the chart sets -72
dBm/56.8 uV as S-9, vice 73 dBm, 50 uV. 1 dB isn't much to quibble
about, but it does make me inquire about the source of the data.

Actually, it is 146dB lower than that... 50µV in 50 ohms is -73dBm.

Owen

Yeah, I missed a minus sign there, didn't I? Good catch.
Here it is: -

Sal

I seem to recall that the KWM-2a was calibrated for 100uv for s9. 1db is
well within the resolution of a lot of lab gear. 50uv would be more
appropriate for a modern radio that should be that much hotter. The RST
system of reporting was supposed to be a relative thing anyway.

db relation TX/RX
 

Hello,

Roy, with all the respect i owe you, you are barking up the wrong tree.
1 S-point should be 6 dB. Manufacturers choose not to do this for
obvious cost reasons. Yet this is the definition, and they should work
on it, especially so now, with digital techniques.
Remains the definition of S9, supposedly different on HF & VHF. I am not
so sure about this, but strongly support HF S9 = 50 uV.

Thanks for your enlightening comments on this newsgroup.

Olivier, HB9CEM / AE7AL





Roy Lewallen wrote:
Thanks for the references.

Where does the fiction come from that an "S-unit", presumably the marks
on our S-meters, is or for some reason should be, 6 dB -- that this is a
"correct" or "ideal" value? To me it's the same as "defining" pi to be
3.2, as the Indiana House of Representatives once did. "Defining" an
S-unit to be some value has no effect on our S-meters, any more than the
proposed Indiana law changed the ratio of the circumference to diameter
of a circle.

Roy Lewallen, W7EL

Jeff Liebermann wrote:
On Sun, 19 Jul 2009 03:00:51 -0500, "Rollie"
wrote:

www.qsl.net/k5lxp/projects/SMeter/SMeter.html

Check the chart to see actual input readings. I've always used the
(6db per S unit) as a general rule-of-thumb.

More receiver S-meter testing:
http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/SMeterBlues.htm#

http://www.smeter.net/slc/signal/strengths.php