The German website describes how this om has developed his capabilities over the years, based on his specific circumstances and needs. This has resulted in a measurement technique with arguable advantages, achieved with a homebrew, very specialized test setup, implemented for the 40m band. While the author apparently had access to some lab-quality test equipment for testing his home-brew test equipment, it appears to me that it would be much more expensive to implement his receiver testing setup using only a combination of off-the-shelf lab test equipment, if that is even practically doable. I haven't read everything on the website, but for those who find the German confusing, the following is my summary overview of some of the site content. He put up a huge horizontal V antenna that picks up high signal voltages from BC signals etc, so rx overload and even damage is a concern. His latest home-built rx is good, but he still looks for improvements, and he focuses on preselectors as a possible way to improve performance. Preselectors don't seem very popular these days, but the author makes a case that at least for his extreme conditions, they can contribute in a meaningful way to how strong, nearby interfering signals can be handled. This turns out to be the case for his homebrew rx and also several commercial rigs, including the K3. The K3 of course has its roofing filter as standard equipment. The IC-751 and an FT-1000 Field have both been modified to add roofing filters that are not part of the original design. The IC-7300 which places its ADC at the front end, cannot be so modified due to its basic architecture, and is tested as manufactured. To test for unwanted response to nearby strong signals the author used 3 types of test setups: IP3 (two input frequencies), continuous noise spectrum (measuring Noise Power Ratio) , and the broadband spectrum carefully generated by pulses, which varies with pulse frequency. The latter method is considered the best, and most similar to real band conditions, and applicable to all the tested receivers (the IP3 method makes no sense for the IC-7300 type architecture). The pulse generator setup has a notch filter that keeps the pulse spectrum out of the rx passband, which is set to 500 Hz. When the power of the pulses is cranked up, the rx does respond eventually, but the higher the pulse power tolerated, the better the rx. The table presented shows "tolerated" (in some sense) pulse power in dBm for the different receivers with and without use of the homebrew preselector, which always helps.
73, Erik K7TV -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Bob DeHaney Sent: Friday, April 06, 2018 12:52 PM To: elecraft@mailman.qth.net Subject: [Elecraft] OE3HKL's Measurements You are correct Breitband means Wide Band in English. Only his home-built receiver is better than the K3 measurements Vy 73 de Bob DJ0RD/WU5T --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ______________________________________________________________ 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 ebasil...@cox.net ______________________________________________________________ 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
