Let's say for sake of example we are in the 40m band.
I've read articles and posts about riding the RF gain (or even just simply lowering it). And I can see how it is useful in overload situations.
What I don't quite get is how lowering the RF gain can help dig a weak signal out of the noise. A "weak signal" just means that it's not much stronger than the noise floor. Lowering the RF gain will lower the noise floor. But it will also lower the signal as well.
How is it possible that lowering the RF gain will attenuate the background noise faster than the desired signal. If you lower the gain by 3dB. Everything goes down by 3dB, right? The SNR doesn't improve.
I've also heard of "riding the RF gain" where you crank up the AF and use the RF as your volume control. How does this help? You are lowering the noise floor and the desired signal by the same amount with the RF gain. And then making it loud again with the AF gain.
There must be something happening when going from the IF to audio then benefits from having an overall quieter signal I guess. I just don't see how any of this can somehow know to attenuate static and amplify desired signal more.
Is dynamic range an issue with weak signals? I can see it being a problem with strong signals (hence the overload and need to attenuate). But with a weak signal, unless your noise floor is S9, you have enough dynamic range right?
Articles (i.e. forum posts)
Next, with the RF Gain still all of the way Counter-clockwise, so that the radio is nearly silent (don't move the RF Gain yet), we bring the AF Gain (volume) up to a quieted -- not quite normal listening level, where we cut hiss, but still just hear the signal clearly.
Once that AF Gain volume is set (about half for Icom 7300), you just leave it where it is, roughly, but you will twiddle it a bit up or down, to keep HISS down to lowest possible levels, as your slowly raise your RF Gain. You are now using your RF Gain as your volume control, by turning it clockwise to raise the volume, or counter-clockwise to lower the volume. While you are adjusting your RF Gain, you are looking for a happy medium between where signals are loudest, but the noise around them is quietest.
… I also twiddle with the AF Gain a little bit, if that helps the signal -- it really depends. Experiment!
With AF gain on full, while using the RF gain to control volume, and aggressive EQ settings on upper-middle frequencies, signals barely readable often rise to an easy 56 to 57.
My KX2's RF Gain, when used with either ATT or Pre-amp, and EQ, will dramatically cut hiss noise while digging out signals.