Jack,
If your tower guys are non conductive, you could try a full wave delta loop
in a triangle configuration and feed at one side for
vertical polarization. It would give you some gain, less noise and a lower
radiation angle than your previous inverted vee...Do a google search or look
for them at ON4UN´s book. Hope this help. 73
Fernando EC1CT // KD0IGJ
E-Mail: ec1ct@esbesaya.com
KR DX Group
--------------------------------------------------
From: "Jack White" <m5pro@hotmail.com>
Sent: Thursday, December 27, 2012 4:50 PM
To: "Towertalk" <towertalk@contesting.com>
Subject: [TowerTalk] 80M Ideas
Hi
I've been reading the ON4UN book and antenna articles online on and off
for a couple of years now but I thought I'd share my situation with some
more experienced Guys on here to see if I can perhaps find some new
information and ideas.
I have a modest HF/6 station that covers 40-6. I have a painted 3 section
60ft Versatower (suspect v. poor electrical connection between sections)
with an Optibeam OB1-4030, Optibeam OB9-5 and 5L 6M Yagi all mounted on a
15ft stub mast and fed into an Array Solutions Ratpak. (Antenna pic on
QRZ) The 6M Yagi has grounded elements but the Optibeam elements are
insulated from the boom and tower. The station is working nicely now so I
feel it's time to add an 80M DX TX antenna. I am interested in 3.5MHz CW
only, so bandwidth/phone etc not an issue.
In the past I've tried an 80M coax fed inverted vee with the apex at
60ft - as expected dynamite out to a couple of thousand miles but no good
for DX. I've ruled out the possibility of shunt feeding the tower because
of the Optibeams and the poor connection between sections. So currently
I'm left with two ideas:
MFJ-1792 or Butternut HF2V mounted 50ft from the tower (landscaped gardens
prevent mounting anywhere else)
Inverted L hanging off the tower with approx 60ft vertical section.
What I guess really matters is the tower's resonant frequency, looking at
the details above, would anybody like to guess? Because the Optibeams are
insulated from the tower do they still effect the tower's resonant
frequency? If it is resonant close to 80M I guess the RF fed into a vert
50ft away would see it as a parasitic element?
In the worst case scenario, if the tower messed with a vertical I could
always lower it before operating on 80M but it's not ideal.
Apologies for any stupid questions and Merry Christmas to you all!
Jack G8DX
Sent from my iPhone
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