Mistake on my math, I should have said I could copy him 26 out of the 29 days, I could just detect him 1 day but not copy him, and then the remaining 2 days I did not listen for him.
Don (wd8dsb) On Fri, Aug 11, 2017 at 8:55 AM, Don Kirk <wd8...@gmail.com> wrote: > This is a follow up to my post about a month ago regarding how well I > heard Manuel (LU5OM) when he was using a dipole (mounted as an inverted > vee) on 160 meters. Since then I have made a point of getting up everyday > (typically 5 am EDT) to listen for Manuel, and to spot him if and when I > hear him. > > The main reason for this post is to say how amazed I/we have been that out > of the last 29 days, I have been able to hear Manuel each day with a few > exceptions (25 days I could copy him, 1 day he was faint but not really > able to copy him and on the remaining 2 days I did not try to copy him > because one day he was not on, and the other day I had a bad lightning > storm). It's like clock work that I turn the radio on, and there he is but > sometimes faint (I would have never thought this possible). Also I might > mention that my RX antenna (pennant that's 51.6% the size of a full size > pennant) is nothing to brag about, but it's definitely better than my TX > antenna (my RX antenna typically has an approximate 2dB signal to noise > level advantage for this long haul stuff). > > The main point I would like to make with this post is that during the 29 > day period it has not been like a open or closed propagation situation, but > rather slightly better or poorer propagation regarding signal strength each > day. (Note: 5am EDT (0900 UTC) was about 1.5 hours before my sunrise, and > just as long if not longer before Manuels sunrise). > > Also very early on during this 29 day period Manuel changed his feedline > over to open wire feedline which allows him to switch his TX antenna from > the inverted vee configuration to basically a top loaded vertical (what he > has been calling a Marconi Tee). Same antenna with the two feeder wires > tied together at the output of his antenna tuner. > > In all honestly the dipole has almost always been as good if not better > than the Marconi Tee configuration (often very similar results and with > static crashes very hard to put firm signal strength numbers on each for an > exact comparison). > > The dipole (inverted vee) also provides a lower receive noise level for > Manuel, and therefore this is typically his configuration of choice. I did > some quick modeling, and the inverted vee configuration definitely does not > hear well at low elevation angles, and this might be why the RX noise level > is lower than when this antenna is in the Marconi Tee configuration when > exposed to Manuels high noise level environment. > > Note: Modeling suggests that above an approximate elevation angle of 35 > degrees Manuels dipole (inv-vee) would have a gain advantage over his > Marconi Tee configuration whereas below 35 degrees the Marconi Tee > configuration should be better (I modeled his Marconi Tee using 4 full size > elevated sloping radials to keep things simple, whereas Manuel is using > buried ground radials). > > Note: Manuel runs 500 watts output power. > > Manuel apologizes for not hearing as well as he can be heard, and he is > currently working on some different RX antenna configurations with hopes of > improving his receive performance. > > Just FYI, and 73. > Don (wd8dsb) > > > > > > > _________________ Topband Reflector Archives - http://www.contesting.com/_topband