Date: Fri, 5 Oct 2018 11:11:39 -0400
From: N4ZR <n4zr@comcast.net>
To: TowerTalk <TowerTalk@contesting.com>
Subject: [TowerTalk] Length of Inverted-L.
<What to do when two respected references differ?? ON4UN's book assumes
<an Inverted-L is always a quarter wave ~135 feet), while the ARRL
<Antenna Book assumes 165-170 feet.? ON4UN mentions longer antennas to
<increase feedpoint impedance, but doesn't seem to put much faith in that.
<Comments?
--
<73, Pete N4ZR
## 165-175 feet works good.... BUT you then requires some series C to
cancel out the XL
of the aprx now .375 long ant.
### ~135 feet may well result in less than 50 ohms. No big deal, a helical
hair pin coil across the
feedpoint will increase the feed Z up to 50 ohms. But the ant has to
initially be a bit shorter to provide
for some XC. Its just a step up L network. Then you also have DC
grounded the ant as well.
And the ant is a lot shorter than a .375 ant.... which may well be easier to
install etc.
## A buddy used a motor driven vac cap in series with his 160m GP, which
has a T top loaded
capacity hat.. sorta like an inverted vee on top..with the center supported on
a catenary line between 2 x trees.
Then it tunes the entire band from 1800-2000. Fixed caps, or relay switched
cap assy could also be used.
In his case, the vert portion is 100 ft tall..with the capacity hat T also at
the 100 ft point, with sloping ends.
### But if u can only go up say 40-50 ft..... you might not want to go
horizontal for another 120 ft.... to make the
.375 ant... along with a series cap. You would end up with a substantial
Horz polarized component.
Jim VE7RF
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