So yes, there are a BUNCH of variables that determine whether the DX station is going to hear your signal.
My approach -- though this has been confined to 6 meters up until recently, when I got back on HF CW and digital modes with a VERY small footprint -- has always been to do whatever I can to make sure the other guy CAN hear me. That means the best antennas and the most power I can put together, in combination of course with the smartest operating practices I can learn and master. The QRO part of that, well, that's just me. A lot of guys love the thrill of beating their heads against a brick wall -- sorry, I mean, the thrill of working DX with QRP and small antennas. :-) Notwithstanding big differences in things like power and antennas, however, I think the two principle reasons for assuming the DX station will eventually be able to copy you are: (1) Their locations are probably quieter than yours -- sometimes (as in an island DXpedition location) a LOT quieter, maybe as much as 10 dB or more quieter. (2) Guys who run DXpeditions or who run their home stations from rare entities are usually very, very good operators -- probably better than you are, for sure better than I am. Since I've been back on HF CW chasing DX with my puny little sloper and 100 watts, I've seen many, many DX stations go to extreme efforts to pull through a complete QSO with a weak W/K station (like me) that they absolutely do NOT need to work for any pragmatic reason, other than personal pride in operating skills. And some of these guys' skills are just amazing. Bill W5WVO -----Original Message----- From: Kok Chen Sent: Sunday, October 31, 2010 18:44 To: Elecraft Reflector Subject: Re: [Elecraft] K3 APF Adjustable Q On Oct 31, 2010, at 10/31 10:05 AM, Byron Servies wrote: > Naieve newbie question, because im missing something here: if the > signal you want is that hard to receive, what are the chances the > other station will be able to hear your reply? Since I use simple antennas, and even though I always run barefooted, I *always* assume a DXpedition to an isolated island can copy me when I can barely copy them above the noise. Although Reciprocity Theory states that if both of you use the same power, the received power at the two antenna terminals will be the same independent of what antennas are at each end, other things determine if he can copy you better than you can copy him. The obvious factor that influence whether he can copy you is therefore obviously the amount of power that you use compared to the amount of power that he uses. However, another factor, arguably more important, is the antennas' directivity and where the directivity are aimed at. If his antenna is more directive than yours by 3 dB, all else being equal, he has a 3 dB of SNR advantage. If the arrival angle of his signal at your antenna is 10 dB below where your antenna actually peaks, while your signal arrives at his antenna where the response of his antenna peaks, you have yet another 10 dB disadvantage, etc. The same SNR argument applies to how noisy his local RF environment is compared to your environment. And of course, how optimal and easy to use the filtering at his end is to pull your signal out of the noise, which is what the APF is all about for CW (and correspondingly, the use of matched filters for digital modes). 73 Chen, W7AY ______________________________________________________________ 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
