[Elecraft] A very desirable capability

[Bob McGraw K4TAX]

One point I've observed is the fact the noise on a given band may not be 
the same from day to day, or week to week.  Thus I find it necessary to 
tweak the values of NR and NB for best performance. Same issues with 
band to band, i.e. what I need on 80M is no where close to what I need 
on 6M in terms of NR and NB.   And, the NR and NB are very different in 
their performance character in terms of handling noise artifacts.

One thing that also helps is to use minimum necessary RF gain and 
correct utilization of Attenuation.  Thus on 160M and 80M and to some 
extent 40M, I use 15 dB Attenuation and reduce the RF gain a wee bit.  
In doing so, the signals pop out of the noise.

A point to consider is optimum receiver performance occurs when the band 
noise floor is 10 dB to 15 dB above the receiver noise floor.  Since we 
can't really change the receiver noise floor, we must change what is 
arriving at the front end.  This means some degree of attenuation and RF 
Gain reduction is required.  For the math.......if no signal band noise 
is -97 dBm or S-5 and the receiver noise floor is - 125 dBm, a 
difference of 28 dB, the receiver should have 15 dB of attenuation 
activated.   You can do the same with the RF Gain by reducing it about 3 
or 4 S units. Too much RF gain being utilized in an attempt to hear weak 
signals is not necessarily a good thing.  As one goes higher in 
frequency, usually band noise decreases and finally to a point where the 
PRE should be used.   In many cases I've heard hams describe the use of  
ATTN is to prevent receiver overload.  While true under some cases, most 
residential QTH locations and antennas won't encounter enough signal to 
overload the receiver.  Thus the ATTN function is more beneficial when 
used in correct receiving gain structure.

73

Bob, K4TAX



On 8/22/2017 4:11 PM, Don Wilhelm wrote:
> Peter,
>
> Since "one size" does not fit all noise sources, I believe that what 
> you suggest is not practical.
> It may be that something could be done to provide the most useful 
> noise reduction for "average noise", but the closest to that right now 
> would be the default settings in the K3/K3S.
>
> If you do not know what the default settings are, save your K3/K3S 
> configuration, then do an EEINIT (Reset to Factory Defaults), then 
> look at the NB and NR settings.  Finally load the saved configuration 
> file and then set the NB and NR settings to the defaults that you 
> recorded. Be aware that some of the settings are per band, so you will 
> have to check them on each band.
>
> That will give you a "one button" NB and NR as you might find in many 
> other amateur transceivers.
>
> I am glad that the K3/K3S offers adjustability for the NB and NR 
> parameters.  It does take some study to learn how to use the 
> parameters provided, but if you do that study, you will be rewarded 
> with good noise reduction for most any type of noise.
>
> 73,
> Don W3FPR