[Elecraft] K3 Noise Reduction

[Jim Brown]

Lots of good advice here. A major problem with the K3 NB is the way it 
is described on screen and in the manual. There are two blankers, one 
ahead of the crystal roofing filters, one after them. Each has multiple 
tweaks. In contest conditions, I've found good noise reduction from 
using the one AFTER the roofing filter, and set for the greatest depth 
and shortest time. I THINK it's called the DSP Blanker.

Yes, by their nature, NBs will modulate signals by the noise.

Let's hope the NB in the K4 is better.

73, Jim K9YC

  On 12/15/2021 8:52 AM, Bob McGraw wrote:
> The approach I use for the Noise Blanker is this.
> 
> I first activate the NB and then the Level.   I start with the DSP OFF 
> and the IF OFF.  I then adjust the DSP value for optimum results without 
> it destroying the quality of the signal.  DO MAKE A NOTE OF THIS VALUE. 
> Then set the DSP back to OFF.  Then move to the IF and scroll through 
> the settings in an effort to find optimum results.  Once this is done, 
> leave the IF value as determined and return to the DSP and set it to the 
> value previously determined.
> 
> This works for a given band and given type of noise.  Change bands or 
> noise and do it all again.  There is no ONE setting correct for every 
> condition.   Right now my 6M noise buzz is S-7 with the NB off.  Then 
> turning it ON and adjusted as above the 6M noise is S-3.  That's 4 S 
> units or 24 dB improvement.  I doubt you will get much better than this.
> 
> As to Noise Reduction, I find it best performs for CW mode. Again it 
> takes careful adjustment to obtain optimum results.   I don't use NR for 
> SSB signals. I prefer to adjust the Attenuation value and the RF Gain to 
> produce optimum results when operating SSB.   I find optimum results 
> occur when the no signal band noise is about 10 dB above the receiver 
> noise floor.   In order to accomplish this operating point, one will 
> need to use ATTENUATION and RF Gain reduction.   More gain won't aid in 
> receiving weak signals, but just the opposite, as the signal will pop 
> out of the noise.
> 
> I generally find using either NB or NR, but not both, is the better way 
> to operate.  I doubt there is anything wrong with your radio.  Most 
> likely the result is more related to receiver setting parameters.