Yes, but many can be misled with "official looking" information that has cover statements buried in the content. Anyone who publishes information of this nature should be prepared to have it critiqued by their peers. Based on this mail string, it is clear there are numbers and methodologies that are in conflict, raising questions by peers. Jim W6AIM .
-------- Original message -------- From: "Wes (N7WS)" <w...@triconet.org> Date: 9/15/2015 12:37 PM (GMT-06:00) To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 to IC-7800 Comparison? I was responding to the comment that you "thoughtfully" deleted so you could go on with your critique. I know it's hard for some people to believe, but some of us in the unwashed masses are actually capable of deciding what is "useful" to us in our own situations. . On 9/15/2015 9:50 AM, Jim Brown wrote: > On Tue,9/15/2015 7:10 AM, Wes (N7WS) wrote: >> Seems to me that he's just trying to explain himself. > > Yes, but in doing so, he's making it clear that his work does not contribute > useful information to a ham trying to evaluate the relative performance of > radios in a strong signal environment, AND that's what the measurement is > designed to show -- IF the same level of test signal is applied to all of the > radios. > > For me, primarily a contester, secondarily a DXer, the primary factors in > choosing a radio are performance in a strong signal environment, a clean TX > signal, and a very efficient user interface. After hearing Adam speak, I had > hoped that his work would contribute to that process, but because the level of > his excitation varies depending on the shortcomings of the radio, it fails to > provide useful information. > > To clarify -- the strong signal performance and dynamic range of SDRs is > limited by the total voltage at the input to the digital system. If there is > no input filtering (i.e., a preselector, bandpass filter, or hardware > attenuator), the digital system sees the broadband spectrum from whatever > antenna drives it. That's everything from DC to daylight -- AM broadcast, all > the other ham bands, shortwave broadcast, all other users of the spectrum. It > is the SUM of all of those signals that combine to overload the digital > system. When that combined signal level hits digital clip (all bits are > digital zero), the radio stops working. > > It is, of course, possible for the user to add bandpass filters outboard to > the radio, and many contesters with SO2R and multi-transmitter stations do so. > This would, indeed, significantly reduce the input to the digital system to > inband signals. BUT -- SO2R and multi-transmitter stations with closely spaced > antennas could still overload the digital system even with that filtering. > > And there's still in-band QRM to get you to digital clip -- a ham a block or > two away running power amp, or a mile away with his antenna pointed at you, > and the sum of all the in-band signals during a major contest. In EU and AS, > there are big broadcast signals in parts of the 40M band that are going to > sail right through the world's best preselector or bandpass filter without > attenuation. > > My neighbor W6DRX (0.3 miles from me and an active contester) and I both > bought K3s as soon as the radio was announced because we realized that it was > the only way we could coexist and remain friends. :) > > 73, Jim K9YC > ______________________________________________________________ ______________________________________________________________ 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 Message delivered to jbol...@outlook.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 Message delivered to arch...@mail-archive.com
