[Elecraft] Help with IF Noise, DSP Noise, NR settings

[Bob McGraw K4TAX]

The Noise Blanker only affects repetitive pulse noise such as ignition 
type noise.  Lightning and atmospheric is random noise. As to the Noise 
Reduction, I find that use of the Attenuation and RF Gain control is far 
superior to using DSP systems.  Also remember it is Noise Reduction and 
not noise elimination as many seem would like to believe.  If one 
realized 6 dB of noise reduction using the system that's good.   At the 
same time, any noise reduction system will add distortion to a SSB or CW 
signal.

 From very authoritative source, the optimum receiver performance 
configuration is to have the no signal band noise about 10 dB above the 
noise floor of the receiver.    Since we can't change the noise floor of 
the receiver, the option is to change the incoming level of the noise as 
presented to the receiver input. The K3S receiver noise floor is about 
-135 dBM.   If one has a no signal band noise of S-5 or -97 dBm, the 
difference is 38 dB. This says we need 28 dB of Attenuation and RF Gain 
reduction.    That would be 15 dB of Attenuation and about 2 S units of 
RF Gain reduction or 10 dB of Attenuation and about 3 S units of RF Gain 
reduction.     This in no way changes the sensitivity of  the receiver 
nor does it impede the ability to hear weak signals. Unfortunately many 
hams belie that more gain is needed to hear weak signals.   With 
receivers of 50+ years ago often the receiver noise exceeded the band 
noise.  That however is not true with today's modern receivers.

As to using the Noise Reduction,  I do not use it at all for SSB and for 
CW.   If  I do use it I find  F1 and a value of 1 to 3 about all I'm 
willing to accept.  Of course the type and magnitude of the noise does 
require different settings.

If I use the Noise Blanker I find it necessary to first set the IF NB to 
OFF.  Then adjust the DSP through its values to get what seems to be the 
best result.  Remember the value.  Then set the DSP NB to OFF.   Then to 
the IF noise adjustment and find what seems to be the best result.   
Leave it at that and then back to the DSP Noise blanker and set it to 
the previous obtained value.    This optimized them individually.   I've 
not been successful in trying to adjust both at the same time.    And 
remember it only works on repetitive noise such as ignition noise or 
line noise and not random atmospheric noise.

The receiver gain method works best.   Hope this helps.

73

Bob, K4TAX



On 6/13/2019 6:43 AM, Nr4c wrote:
> This is not an easy thing.
>
> First, are you hearing general band noise, a constant “ shhhhhhhhhhhh” or pulses as in lightning, power line, or ignition type noise.
>
> For band noise, the NR will be your best solution. Experiment, but don’t go too deep. Deep settings will distort and make it sound like you’re underwater.
>
> For the pulse noises, try IF first, again don’t use extreme settings. If this doesn’t work, try the DSP settings and see if this will work.
>
> I have NB set to Med4. NR is set to F1-3.
>
> YMMV.
>
> Have fun!
>
> Sent from my iPhone
> ...nr4c. bill
>
>