[600MRG] measuring noise level ?

[Edward R Cole]

The only equipment I trust for s-meter calib is my Elecraft radios; 
they specifically spec them S9 = 50uv and S3 = 1uv.  S9 is rated at 
-73 dBm for HF and -79 dBm (I think - going from memory) for 
VHF+.  Not sure why the disparity in the 
spec.  http://www.moseleysb.com/mb/mv2dbm.html

I use -73 dBm as my std for signal measurements on all freqs.  I 
built and sold transverters so provided MDS measurements for my customers.

I do not hold any reverence to over S9 readings.  Best to have a step 
attenuator and turn off AGC is you are making precise readings over S9.

73, Ed - KL7UW

At 09:36 AM 7/17/2016, Glen Zook wrote:
>Actually, I have a number of "S" meters that are properly calibrated 
>at S-9 = 50 microvolts and are pretty accurate above, and below, 
>S-9.  However, I do agree that the majority of "S" meters, 
>especially on "modern" transceivers, are not properly calibrated and 
>are, in general, "very" generous!
>
>
>
>I hear reports of 40 dB over S-9, and even 60 dB over S-9, being 
>given on a regular basis.  The signal level required for a 40 dB 
>over S-9 is 5,000 microvolts and for a 60 dB over S-9 is a whopping 
>50,000 microvolts when S-9 is 50 microvolts.  The Japanese 
>manufacturers got into a "war" quite a while back with each claiming 
>that "their" radios were more sensitive than those made by the other 
>manufacturers.  However, basically, all that they did was to change 
>the calibration of the "S" meter so that it read higher with a 
>considerably lower signal level.  But, the average operator, these 
>days, just accepts what the meter reads and, as such, gives out a 
>higher reading than what a properly calibrated "S" meter reads.
>
>
>
>Glen, K9STH
>
>Website: http://k9sth.net
>
>
>
>From: Edward R Cole <kl7uw at acsalaska.net>
>To: 600mrg at w7ekb.com
>Sent: Sunday, July 17, 2016 11:13 AM
>Subject: Re: [600MRG] measuring noise level ?
>
>Most likely the poster of that noise measurement intended to say -85
>dBm.  Spectravue provides direct level measurements of signal and
>noise on a waterfall display.  Most SDR sw do this.
>
>All modern service equipment show signal level in dBm.  I hear almost
>no one using uv anymore (unless they are audiophiles).  DBm are
>direct measurement in power while uv is ac voltage which requires one
>to specify the impedance if it is to relate to power.
>
>So would you rather S-meter reading be given - ha ha!  Show me two
>receivers that have s-meter properly calibrated.
>

73, Ed - KL7UW
http://www.kl7uw.com
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