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
