To: | <towertalk@contesting.com> |
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Subject: | Re: [TowerTalk] TowerTalk Digest, Vol 127, Issue 86 Mesage 7 WX5B |
From: | "Pfizenmayer" <pfizenmayer@q.com> |
Date: | Wed, 31 Jul 2013 18:34:07 -0700 |
List-post: | <towertalk@contesting.com">mailto:towertalk@contesting.com> |
OK - I will throw in my two cents worth - my majestic antenna system is a
KT34 at 42 feet and a 40 M rotatable dipole at 50 feet , and an 80 M inv vee
at 39 feet crammed in a backyard as well a 12 and 30 m dipole strung around.
. I play around in contests both domestic and DX against guys around
here - and one of the guys has done a script that takes RBN reports and
plots them out for most of the AOCC club guys in several contests. Damn
seldom do any of my RBN spots beat out anybody with any kind of antenna at
65-70 feet and above. Once in a while of course I get lucky and the
propagation Gods are with me , but on average they have a lot more louder
spots than I. Of course all this varies by the minute or less.
Having said that , several of them also have lower tribanders for obvious reasons. They all consistently hear stuff I can barely detect if at all. Now some of that is my local noise - the difference between my 30 M sloping dipole - (top at 39 feet bottom at 10 feet across roof) - and the 40M rotatable dipole (on 30 M ) on receive is the difference between copy and no copy on on weak sigs about 50 percent of the time. (SWR is about 8:1 on 30 M on that 40m dipole so with a tuner it seems to be about a tossup on TX.) Half the time I have my KT34 pointed at some direction that allows me to copy - rather than put best sig into that area. Incidentally in the late 1960's I did a little work on a part of a system called ISCAN - this was an array of 24 vertical dipoles almost a mile long up in a salt bog up East and aimed at EU . It generated 24 vertical patterns electronically so you could watch angle of arrival of HF sigs from EU in virtually real time. I got to watch this beast in operation a few times and often in 200 mllisec the angle of arrival would change by 3 to 5 deg or more .Now obviously , on average . at a given time and condition , there would be a best angle . I have always wondered how well just a big stack of dipoles would do since the huge difference in signal level versus angle of arrival is a lot more than 2 dBi versus 10 dBi especially if you are in one of the nulls with a given system. BTW someone talked about K6LL - and a very modest ant system by comparison to many big guns - I wonder if the fact he is on a large flat planar area around Yuma helps some - he does get a big sig out of that system - but he is also simply an incredible op. Enough babble - Hank K7HP Message: 7 Date: Wed, 31 Jul 2013 20:39:40 -0400 From: "W5XB" <w5xb@att.net> The other thing that is harder to calculate, is what you hear, i.e., the received signal. When I had a 4 L Steppir at 76 feet, I heard signals a neighbor ham would call me and say, "I couldn't really copy them." He had a tri-bander at 60 feet. In the old, old days, Mike Ercolino experimented on his signal range, and determined two 3L monobanders, top one 120ft, was a only bit below much taller towers. Mike said, "You need gold in the hills, to gain a few db above 3 over 3."But then there are things like this: K4SSU and I were on the air talking to his friend in Australia. A Hawaii (5k miles) ham broke in to give us signalreports. I got S9 plus ten...and thought that was good, until he gave Dave, S9 plus 30. Dave was also hearing the Hawaii ham about 20 db better than I.Dave had two six L 20m monobanders...top one was at 150, and the bottom one was at 75. My math says, Dave had 20 db on xmit, but he also had about 20 dbmore received signal than a 4L at 75,My fear factor limits me to 104 ft and 4 over 4 (going up in September)...I will just have to live with Dave being about 20+ db louder...no worries :-)And that's my 2 cents y'll. 73, Grant W5XB _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk |
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