Greetings, all....
In the category of "never change a working antenna within 24 hours
of a contest":
My inverted L is coax-fed at the base of a 75' Rohn 25 tower. The
shield is grounded at the tower base and the center conductor is simply
hooked to a wire that goes up alongside the tower (only 8" away from the
tower) to the top and then ties off to a tree. The horizantal portion is
approximately 75' long as well. There are 3 resonant radials elevated 4'
that go off at about 30, 90 and 180 degrees.
Simple. SWR 2:1 bandwidth was 1800 to 1860. No tuner anywhere.
Work about anyone I can hear, including EU w/ 5 watts (but not lately!!).
So, what did I do? I decided that the vertical portion must be too
close to the tower, so I pulled it out about 3' from the tower. No other
changes. Now the SWR doesn't go below 2:1 ANYWHERE and the antenna is
resonant at about 1780 khz. I could shorten it to raise the resonant
frequency, but I don't see that solving my problem. What did I do wrong?
Was my assumption that 8" separation between the vertical portion and the
tower was not a good idea correct or not? Is 3' still too close? I can use
a tuner in the shack and get by for this event. I can change it back but
thought I'd solicit the advice of the group first.
TIA and 73, Jim N9JF
Quote of the year:
"Umpires are like dairy cows. The bottom 20% should be culled each year."
Al Oppendal, Ruthven, IA in Nov. 16, 1998 _Sports Illustrated_
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