I also think that the current max AGC threshold is too low, but I have another question. Why is it necessary for the K3 AGC to have such a sharp elbow at the point where the AGC kicks in? The Clifton Labs plots show such a sharp bend that it seems multi-signal in-band intermod is inevitable, especially with higher SLP settings. Wouldn't it be feasible, and more desirable, to have some more gradual inflection point? I would think that something like a parabolic shape would be better, and the DSP AGC is just the implementation of an algorithm, correct? I suppose that would tend to blur the distinction between different THR settings, but so what?
Maybe somebody can educate me ... 73, Dave AB7E ------Original Mail------ From: "Don Wilhelm" <[email protected]> To: "Joe Subich, W4TV" <[email protected]>, <[email protected]> Sent: Wed, 10 Feb 2010 01:06:09 -0500 Subject: Re: [Elecraft] K3 DSP AGC Question Joe, Can you elaborate your reasons for this suggestion. I had come to believe that the best situation is to place attenuation before the first mixer to give the greatest amount of dynamic range (headroom). Yes, I agree that the AGC Threshold could be raised in the K3 and would be beneficial. I have felt the default of 005 was too low. 73, Don W3FPR Joe Subich, W4TV wrote: > Perhaps one should get the ambient well down in the ADC operating > range but killing gain (adding loss) before the first mixer and > the roofing filter is not the way to do it. If you want to > better align the dynamic range of the receiver (or specifically > the ADC) to conditions, the attenuation should come in the > IF - preferably divided between the first IF and 2nd IF. > > However, there would still be no apparent reason that the K3 > should not be capable of sustaining an AGC threshold at least > 10 db higher than currently set with AGC THR = 008 whether > that be reached with preamp on, preamp off or attenuator on. > > 73, > > ... Joe, W4TV > > ______________________________________________________________ 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
