Hi John: You are correct. When there was no strong off center signal but two or more strong signals within the 50Hz passband it was possible to copy one signal, as we all do, in the presence of QRM. There was no noticeable AGC action. It was just a normal situation of trying to copy one signal out of several. Even at 50Hz you can't remove 100% of all QRM.
When an S8 or S9 signal was around 70Hz away the signals inside the 50Hz passband were quiet until he stopped sending. I wanted to hear what was causing the problem so I used RIT to tune up or down until I could hear the off center signal. When I did I found that the offset was about 70Hz as read on the lower display. I could then also see his signal strength on the S meter. I wish I could say what happened when I opened up the passband but I don't recall. I thought a passband shift might help but the shift is limited to 50Hz increments. So one touch of the shift knob caused me to lose the signal of interest. 73, Mike K2MK John W2XS Mon, 23 Feb 2009 10:18:02 -0800 Is my summary of the issue correct? If both signals are within both the DSP and roofing filter bandwidths, then the receiver recovers instantly after each character. If the stronger signal is outside the DSP filter window (and you can't hear him) but inside the roofing filter window, then there is de-sensing. Would passband tuning (shift) help to shift his signal outside of the roofing filter bandpass? John W2XS ______________________________________________________________ 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
