All Flex radios measure signal strength regardless of the PreAmp settings.
As well, they correctly calculate the power in the receiving passband.
Early superhet radios use maxim signal that was rectified into a DC voltage
to provide an S meter reading and to also drive the AGC. This is why when
the AGC is off, there are no S meter readings. (that is the simple way to
describe it). It is also likely that they are not well calibrated other
than to show that S9 is -73dbm and plus or minus that is not what you think
it should be.
The 'S' value is also calculated based on the 50ohm input level at the
receiver, not the antenna. This will also result in different readings
from different users since antenna systems are all different.
In the end, the information is for reference only and is useful for comping
changes at your own station. Now, if SNR was actually reported then
stations could start to compare similar readings.
Mike va3mw
On Sun, Jan 17, 2021 at 11:10 AM Wes <wes_n7ws@triconet.org> wrote:
> I'm not going to smack this tar baby, other than to note that Elecraft is
> a
> special case with respect to S-meters. K3(S) have an "Absolute" mode that
> compensates for preamp gain or input attenuation. So the S-meter becomes a
> decent power meter.
>
> I think it's unconscionable that other manufactures, with microprocessor
> controlled radios, haven't incorporated this. They should be fully
> capable of
> measuring their own preamp gain and attenuator loss and compensating the
> meter
> accordingly. I throw into this criticism the TS-890 that I just
> acquired. My
> goodness, they went to the effort to incorporate a decoder for PSK, of all
> things, but can't provide a decently calibrated S-meter.
>
> Wes N7WS
>
>
> On 1/17/2021 7:26 AM, Don Kirk wrote:
> > Hi Roger,
> >
> > Signal report comparisons with the modern radios that often have preamps
> > that you can switch in or out really clouds the picture as well as the
> fact
> > most stations on topband use RX antennas. Assuming that all
> manufacturers
> > have S meters that are calibrated identical to each other (which is not
> the
> > case), the big question is if the S meter calibration was done with the
> > preamp on or off, and if the person that is giving you a signal report
> has
> > the preamp on or off. As an example the Elecraft S meter uses the common
> > standard of S9 = 50 uV but the calibration is done with Preamp 1 on. And
> > when a station is using an RX antenna everything goes out the window
> since
> > RX antennas often have very negative gain, and then if an external preamp
> > is being used that adds another variable. And if just using a TX antenna
> > for receive there is a lot of difference in each stations antenna
> effective
> > gain (due to ground losses, etc.) that adds another variable.
> >
> > A signal report of S2 or S6 tells me nothing on how well I am being heard
> > since I need to know what your noise floor is too (unless you are telling
> > me how many S units above your noise floor I am ????). What helps me the
> > most is to understand how many dB above your noise floor I am, and that
> is
> > why you will see that when I spot a station on DX Summit, I say how many
> dB
> > the station is peaking and that means how many dB above my noise floor
> the
> > station is peaking (I think this is similar to what you see for signal
> > reports on the RBN).
> >
> > Just FYI,
> > Don (wd8dsb)
> >
> > On Sun, Jan 17, 2021 at 8:04 AM Roger Kennedy <
> roger@wessexproductions.co.uk>
> > wrote:
> >
> >> Well personally I always give Signal Strength reports from my S Meter .
> .
> >> .
> >>
> >> So it doesn't matter whether my Noise Level is S2 or S6 . . . I'm
> telling
> >> you how strong your signal is at my QTH.
> >>
> >> Roger G3YRO
> >>
> >>
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