W6EL prop program helped me to work my first (and single, so far) Alaska on 80m some 20 years ago.
73, Mirko, S57AD 2017-02-17 18:50 GMT+01:00 Merv Schweigert via Topband < [email protected]>: > I agree seat time is the only sure way. I have tried a number of > different prop programs > and have not been satisfied so to speak. > > What I use now most of the time does not specifically show grey line, but > does do long > and short path, and you can "estimate" grey line by the sunrise / sunset > times shown > and the path predictions to the destination. > > It is the old old W6EL prop program. > > For me it has been very accurate in predicting openings, simple to use. > Have been able to snag needed countries on the low bands using this tool, > its interesting > to be sitting on the freq and hearing just whispers of the DX, and as the > time plotted > by W6EL approaches the signal comes up out of the noise and you have a > shot at > working them. > Some times the window is very short, but it seems to be pretty accurate > as to time / freq. > It only covers 80 to 10 meters by the way. > > 73 Merv K9FD/KH6 > > Hello Kris N5KM, >> >> Thanks for the clarification. >> >> 80m is a different story. Yes, we can predict greyline propagation on 80m >> (I assume when you say greyline propagation, you mean propagation along >> the >> terminator). And our predictions say there is still significant loss along >> and near the terminator on the low bands. Simply put, absorption is >> proportional to the product of electron density times electron-neutral >> collision frequency - so as we progress from day to night, absorption >> moves >> up from the D region to the lower E region. There is still a prohibitive >> amount of absorption along the terminator on the low bands. >> >> What I and others believe is that what really happens is the RF takes a >> short cut across the dark ionosphere, where absorption is minimal. The RF >> gets far enough away from the terminator to minimize absorption, but not >> far enough away to look like it's not greyline. Thus the importance of the >> greyline is to put both ends of the path in or near darkness. For a great >> article on 80m greyline, read Ed N4II's article in the Nov/Dec QEX titled >> "Gray Line Propagation, or Florida to Cocos (Keeling) on 80m". I have >> written about the problems with "greyline propagation" numerous times, but >> N4II's article is more elegant! >> >> So can we predict this alternate explanation of greyline? Unfortunately, >> no >> - as it involves two great circle paths joined by a skew point. Having >> said >> that, many years ago Rod VE7VV developed a DOS program to address these >> skewed paths. I am not familiar enough with it at the moment to offer any >> comments. I believe Bill W4ZV has used it more extensively. One comment - >> the output of this program appears to be in terms of a monthly median, >> since the model of the ionosphere in our prediction programs is a monthly >> median model. In other words, VE7VV's predictions say something like a >> signal will be so many dB above 0.5 uV on a percentage of days. >> Unfortunately, we do not know which will be the good days. Bottom line - >> keep you butt in the chair at the appropriate times. >> >> Carl K9LA >> _________________ >> Topband Reflector Archives - http://www.contesting.com/_topband >> >> > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > -- Mirko S57AD _________________ Topband Reflector Archives - http://www.contesting.com/_topband
