I have a F12 Sigma 80 antenna, which is an OCF vertical dipole with
inductive loading at the feed point and a hairpin match. While it
*requires* a common-mode choke at the feed point, it works very well for
DX. On stateside contacts, I think its radiation angle is too low and
performance for anything within about 400 mi is much worse than for my
inverted V with (apex at 40 ft). On DX, though, it does MUCH better than
the inverted V. I have no radials beneath this antenna.
I know a friend is buying a Greyline antenna for his QTH. They initially
look a bit pricey, but I've not actually seen one, so I don't what the
build quality is truly like. Assuming it's build quality is pretty good,
and assuming it has a good CM choke, there's no reason why it shouldn't
perform relatively well given the constraints. Certainly better than no
antenna at all!
Kim N5OP
On 10/16/2020 7:27 PM, Gary K9GS wrote:
A better way to describe these is that they are an off center fed vertical dipole. No helical
loading. They are working on a 40 ft version. I'm seriously considering a 28 ft one over salt
water. Tuner at the base.73,Gary K9GS
-------- Original message --------From: Jim Brown <jim@audiosystemsgroup.com>
Date: 10/16/20 5:55 PM (GMT-06:00) To: towertalk@contesting.com Subject: Re:
[TowerTalk] Greyline Performance antennas On 10/16/2020 2:26 PM, k7lxc--- via TowerTalk
wrote:> Can anyone shed some light onto the verticals from Greyline Performance?Hi
Steve,The website describes these as vertical dipoles. That suggests that they are
helically loaded. Vertical dipoles don't need radials. They can center fed or off-center
fed. The tallest of these flagpoles, at 28 ft, could work fairly well on 80M. An
important caveat though -- field strength from vertically polarized antennas is strongly
dependent on soil conductivity. That is, the better the soil in the far field in
direction you're trying to work, the better they work.73, Jim
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--
Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)
/"A great second violinist plays second fiddle to no one." //– Robert C.
Marsh, Chicago Sun-Times./
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