In my suburban? location, the noise level on 80m and 40m is quite high and puts the AGC circuit into a non-linear range. rather than using a pre-amp, I use a 24dB attenuator which drops the noise level down and the readability of the wanted signal improves.
Give it a try, many operators are surprised at the improvement. Doesn't work for everyone or for all situations.
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On 23/01/2021 17:01, Arie Kleingeld PA3A wrote:
What I meant is that noise or signal level does not change. It is a fieldstrength outside your transceiver.
Switching on a preamp makes signals more audible (sometimes) but still, then EM fieldstrength is the same. So When the signal is captured with your antenne and comes into the TRX, than you can read on the S-meter whatever the manufacturers like ;-)
Besides that, the noiselevel on HF is usually pretty high in urban areas, signal to noise ratio will not change if you add just that little preamp noise. Band noise is dominant (mostly) except on higher freq bands. Not going into detail too much.
73
Arie
Op 23-1-2021 om 10:37 schreef David Reichard:
Arie: All signals are amplified. So a 10 dB amp would increase the desired signal 10 dB and the noise level 10 dB too. Maybe the signal-to-noise ratio (SNR) does not change--is that what you meant? In the real world, an amp adds its own noise to the noise already in the signal, so the SNR would be worse than without the amp. I'm not an engineer, so correct me if I'm mistaken:)
-David Reichard KD6DWR
