I`ve been following this thread with interest as I have the same perceived problem as John - and think all K3s exhibit this symptom.
I do not believe anyone has mentioned signal to noise ratio and surely this is fundamental ? I work a lot on 160m trying to dig out extremely weak signals using a K9AY loop array with pre-amp on (on the K3). I have tried lots of AGC settings with the K3 but my conclusion is that the best signal to noise ratio is achieved with the AGC off; turning it on in whatever combination of settings introduces noise and degrades the S:N. This conclusion means setting the AF limiter at a suitable level to protect my ears ! 73 Terry G4AMT On 08/10/2010 19:55, Don Wilhelm wrote: > I seem to have trouble convincing some to raise the threshold to > combat the noisy effect. Please read all below carefully, and I believe > I can offer some explanation. > > Let's study what the AGC SLP and AGC THR settings do and try to relate > them to the perception that the K3 is noisy. > > IF -- > the threshold is so low that the noise triggers the AGC (and that will > be happening if the noise is causing the S-meter to have a reading with > no signal) > AND -- > If the slope is set to a high value which makes all the signals have > more or less the same audio volume, > THEN -- > The noise will appear at about the SAME audio volume as the signals. > RESULT -- > A K3 that sounds noisy :-( ! It is a combination of both the threshold > and the slope that create this condition. > > The cure for that situation is to increase the threshold and reduce the > slope. > How much? > That is an individual decision, but I have mine set to the extremes of > THR at 008 and SLP at 002. > I really believe the defaults are OK for a band where the ambient noise > level is lower, but certainly gives problems on a band that is > inherently noisy. > > Please make your evaluation while listening to signals and the breaks > between signals - if you are hearing only noise, you will naturally turn > the AF Gain up, and yes the noise will increase - not only that, with > only noise, the perception is that one should use a lower threshold setting. > That is because as you lower the threshold, the AGC response to the > noise gets stronger, and the audio level is reduced by the AGC - what > you are perceiving is exactly the opposite of what you wish to achieve. > > In addition, turn the attenuator on and the preamp off - again, if you > hear an increase in the band noise when the antenna is connected, you > have all the sensitivity that you can use for that band and antenna. > The K3 remembers those settings by band, so you don't have to make > changes as you switch bands. > > 73, > Don W3FPR > > On 10/8/2010 2:23 PM, Mike Scott wrote: >> I have thought about John's wish for more AGC control. The K3 has a lot of >> gain, I wonder if greater attenuator control would be more useful. I would >> like to rotate in another 10 or 20 dB attenuation at times when operating >> lower bands. I would guess my that wishes would require hardware >> modifications and John's may not. >> >> >> >> AE6WA >> >> Mike Scott >> >> K3, KX1 >> >> >> >>> John G3XRJ said: I've played around with various AGC settings and in >> particular the >> >> AGC THR - which if it would go 2 or 3 points lower would appear to >> >> address the problem. >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
