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.
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