John Chappell G3XRJ wrote: > > Don, > > What I should have mentioned in my initial post was that the recording > was made at midday on 80m and the noise from the antenna was only s1. > For a given setting of the rf gain, increasing the threshold to 8 > increases the noise, as can be heard in the recording. > >
It doesn't increase the noise, it just makes it sound louder. You need to turn down the AF gain to restore the noise to its original level. Or tune in a signal and adjust it to the same level as before, you should find you need less AF gain and the noise when the signal isn't present will be quieter. As Don stated you probably have too much front end gain because the reason increasing the threshold makes the noise louder is because the noise is strong enough to activate the AGC when the threshold is set low. Any receiver will sound noisy if you use preamplification when you don't need it. The important difference is that increasing the threshold and decreasing the slope increases the volume of signals relative to the noise and makes strong signals sound louder than weak ones. It's hard to explain and the adjustments are not very intuitive but a few months ago I tried different settings using my XG1 to generate 50uV and 1uV signals and observed the audio output on a scope, then it became clear what was happening and how the adjustments affected things. ----- Julian, G4ILO. K2 #392 K3 #222. * G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-AGC-THR-doesn-t-go-low-enough-tp5614723p5616667.html Sent from the [K3] mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
