Yeah, it's probably the best built antenna I've seen short of towers as
antennas. It's quite heavy, too. I can see why you chose to not schlep
it back to the States. I hope it's serving the local club well.
Kim N5OP
On 10/17/2020 5:37 PM, kdutson@sbcglobal.net wrote:
Holy colossal vertical dipole! You guys were serious. N6BT made his antenna
with pretty stout aluminum, and you found out why. It was a bear carrying it
from Houston to London to Malta, but worth the effort.
73, Keith NM5G
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Jim Brown
Sent: Saturday, October 17, 2020 5:15 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Greyline Performance antennas
On 10/17/2020 1:24 PM, Kim Elmore wrote:
Maybe I should have said "... making sure it has a good CM choke,"
especially since you've taught us how to make them! Even if the feed
is in the center (it could be if the transmission line is run up the
bottom
half) it still won't be balanced. A CM choke is always needed. I've
become convinced that balanced antennas make analysis much easier
(even
possible) but that in the real world, there aren't any. I have no
idea what the electrical length is for 6 m or even 10 m, so the low
radiation-angle assumption might be invalid on those bands.
Here are slides for a talk I gave on the Pacificon Antenna Forum several years
ago on an 80M vertical dipole for our 7QP and CQP expeditions, based on N6BT's
design ideas. Yes, it does need a serious choke were the coax feeds up through
the tubing to the feedpoint.
http://k9yc.com/80M-FDVertical.pdf
Testing it in Glen's pasture showed it to significantly outperform an inverted
Vee with the center at 46 ft, but mechanical issues with the design caused us
to abandon it after modeling and building several alternative designs.
73, Jim K9YC
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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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