http://elecraft.85.s1.nabble.com/K4-S-meter-characteristics-tp7660056p7660078.html
Agree completely. I find all S meters to be totally inaccurate and next to useless, including my K3S’.
> On Apr 24, 2020, at 7:43 AM, Morgan Bailey <
[hidden email]> wrote:
>
> Maybe it is just me but, Turn the radio on, adjust the audio/rf/agc
> controls, hear the station, work him, move on. I dont need a fancy dbm or
> an iconic number of engineering controls, to say what the dbm was when I
> worked the guy. When you contest, who the hell cares, hear him, work him,
> move on. In simple terms, I just want selectivity, and no agc pumping and
> no front in desensing from a 40 db over nine station 2khz away.
>
> Im looking forward to a quiet front end, that keeps me from having to
> listen to 48 hours of static that is generated by the stages with in the
> radio. Love my K3S, great radio. Simple to operate once you learn its
> controls and never has failed me.
>
> Looking forward to K4 delivery.
>
> Vy 73,
> Morgan Bailey NJ8M
>
>
>
> On Thu, Apr 23, 2020 at 11:33 PM Al Lorona <
[hidden email]> wrote:
>
>> Now that the K4 has exact knowledge of its gains and losses through the
>> preamps, attenuators, splitters, bandpass filters and so forth, could this
>> enable an alternate way of visualizing the receiver's range? This alternate
>> measurement would be quite useful in setting the controls optimally for any
>> situation.
>>
>> Imagine a scale -- I suppose it would be in dBm -- showing the K4's total
>> dynamic range. Say it's 100 dB in total. The lowest point is the minimum
>> discernable signal (MDS); the highest point is the damage level, or if
>> that's a bit too frightening, call it the maximum ADC level or something
>> else to denote it as a Level Not To Be Exceeded.
>>
>> Since the K4 will know not only what the noise floor of the band you're
>> listening to is, but the absolute value of that level in dBm, the scale can
>> be annotated with a dynamic marker to show where the band noise falls in
>> that 100 dB range. I'm calling it 'dynamic' because it'll vary a few dB as
>> band noise does, but it will sit at a calibrated level, relatively
>> motionless on the scale as Wayne described the S-meter doing.
>>
>> As the operator kicks in more gain by turning on preamps or turning up the
>> RF Gain, the scale shifts downward by the same amount. For instance, if the
>> scale was showing -120 to -20 dBm -- a 100 dB range -- and then the
>> operator turns on a 10 dB preamp, the scale must change to -130 to -30 dBm,
>> because the preamp has made the receiver more sensitive while also reducing
>> the max permissible level.
>>
>> Conversely, if the operator turned on 10 dB of attenuation, then the scale
>> would shift upward to -110 to -10 dBm, indicating clearly that sensitivity
>> is being sacrificed for greater large signal handling capability. The noise
>> floor, being a relative constant, would move closer to the bottom of the
>> window, or rather, the window would move relative to the noise floor in
>> such a way as to place it 10 dB closer to the bottom end.
>>
>> So actually, as I'm thinking about this, the meter wouldn't move at all.
>> It's the noise marker that would float higher and lower within the window
>> as you varied the controls, just as on an S-meter. I guess what I'm
>> describing here is more or less an S-meter calibrated in dBm!
>>
>> But perhaps the best reason for looking at the receiver this way would be
>> to tune the controls precisely for a given noise floor. Twenty meters, with
>> its -120 dBm noise floor, will require one combination of preamps and/or
>> attenuators. On 80 meters, if the noise is, say, -100 dBm, the operator
>> knows (because he can see the graphic) exactly how much attenuation is
>> acceptable while still keeping the band noise marker in the operating
>> range. It would behoove the operator to keep the noise floor marker near
>> the bottom to 1) give him the maximum dynamic range under those conditions,
>> and 2) to avoid becoming "my K4 is noisy" guy.
>>
>> Presumably, as each K4 goes through RF calibration at the factory it will
>> know exactly the gain of each preamp, attenuator, filter, and splitter in
>> its path. The scale could be custom for each individual unit, although I
>> wouldn't want to start any "my K4 is more sensitive than yours" wars.
>>
>> I leave it to the programmers to decide on the specific eye candy of such
>> a readout. I for one would find this type of meter fun and useful in
>> getting a mental picture of where in dynamic range space the receiver is
>> sitting.
>>
>> Can anybody see any flaws in this idea? I can foresee at least one. I
>> don't know how the front end of the K4 will work, but if it is constantly
>> moving the receiver range in response to what it hears, that is, in
>> response to the total amount of power incident on its antenna port, then
>> perhaps that might pose a real challenge to giving this type of feedback to
>> the user. I don't know.
>>
>> Al W6LX
>>
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