Next time you use your transceiver’s noise blanker (or blankers, in the case of the K3/K3S), you might try the following experiment: Turn AGC off, and possibly the preamp as well, when doing noise blanker level adjustment. You may need to back down the AF and/or RF gain controls to hit a comfortable receive signal level.
When AGC is ON, it compresses everything, both signals and noise, to the point that it’s sometimes hard to hear the true effect of blanking. This is especially true when multiple complex noise sources are present.
With AGC off, you’ll better hear the effect of different noise blanker settings.
As an example, I have a very high noise level at my QTH on 40 m tonight, a combination of narrow pulses (arcing poles), local light dimmers and appliances, and stochastic (atmospheric) noise. I turned the blanker on and initially thought it was having little effect. I then turned AGC off and was able to fine-tune the DSP and IF blanker settings on the K3S using my ears and the S-meter.
An S-meter won’t tell the whole story. But in this case, my settings resulted in a 15 dB indicated reduction (about 3 S-units), and a definite improvement in weak signal copy.
If you turn the AGC back on, noise blanker performance may be about the same in terms of improving S/N ratio of on-air signals, but turning it on/off will be a lot less dramatic due to gain compression.
(Note: Don’t forget to turn the RF gain back up as required. This setting is a global value, not per-band, and you probably won't want the gain reduced on quieter bands.)
73,
Wayne
N6KR
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