Ralph,
I really liked your post.
I don't quite follow your bit about being against 450 Ohm feedline but the
rest of your post was indeed impressive. Maybe you know something I don't
know..
Long low band antennas, used on the high bands, regardless of how good the
SWR looks, are a waste. Less is better. A short dipole with maximum 6m (19
ft.) per side is the longest the dipole should be. Otherwise the two major
lobes will break up into several smaller lobes with multiple peaks and
nulls. Not good.
20 ft. per side is borderline. I'm not sure. I would make it just 19 ft.
per side to be on the safe side.
I don't have a lot of experience with FD in USA. I have won outright, FD in
Europe several times.
Here in Europe, one of the best FD antennas one can have is a lazy loop (for
80m).
This is basically a horizontal loop, 84 meters (21 meters per side), mounted
about 30 to 40 ft. high. It is fed with 300 or 450 Ohm openwire and matched
with a Johnson Viking matchbox (or Annecke). It may also be matched with
other solutions.
Ralph's statement about using an "L" or "T" matchbox is correct, though
using a "Symmetrical L" such as Palstars BT-1500 or a "Symmetrical T" such
as MFJ's MFJ-976 do work very good. The Link-Coupling of the JV Matchbox
(or the Annecke, it's German successor) gives you about 20dB more of common
mode impedance which is a great benefit. It is often quieter than the other
technologies.
There are some ways of using lesser matchboxes but for now I support what
Ralph said.
Categorically rejecting an OCFD is like shooting yourself in the foot.
I would suggest you aren't up to date on the latest OCFD technology.
Your information you have is probably sound, based on what we knew 15 years
ago, but simply no longer true. (Not you Ralph, that bit was for the
original OM that started the thread).
Ralph's post was super.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Ralph
Matheny K8RYU
Sent: Tuesday, April 14, 2015 6:08 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Field day antennas
In my experience the 80M antenna on the higher bands will be a dud. If you
must, use a loop rather than an dipole, and feed the loop with 300 (NOT 450)
line via a true balanced link-coupled tuner, like the Johnson Matchbox of
60's fame. Both 80M antennas have just too many nulls on the higher bands.
T or L network tuners with "baluns"
at the input or output have not impressed me in this service, but that may
be a personal prejudice.
I think a short dipole for the higher bands is worth the trouble, say about
20 feet on a side, again with 300 ohm feed line.
I stay away from the 450 stuff because one can end up with some VERY low or
high Z at the tuner, and since the bands are harmonic related if it's good
on one it will be bad on another to a much greater extent. If I could get
150 ohm open wire, I'd use it!
One man's opinion.
de K8RYU
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