Jim has given some good advice.
Another thing that helps when running 2 transmitters on the same band (i.e.
40m or 20m) is to use different polarities of antennas; one horizontally
polarized and one vertically polarized.
Then separate as far as possible.
It's better to have 1 or 2 dB of additional loss in the coax than to have 10
or 20 dB of intermodulation or broadband noise on receive all the time.
Running them in parallel is the worst thing that you can do.
For me, parallel means the wires are in parallel just as the elements of a
beam are in parallel.
Instead, mount them end-to-end or rotated 90 degrees and of course separate
as far as possible.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of
lciotti@lrlc.us
Sent: Wednesday, April 15, 2015 3:42 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Field day antennas
All this field day antenna talk has me wondering... In multi setups, I
know distance helps, but is it true that keeping the antenna parallel also
helps? We are considering going from three stations this year to 4 so
that is going to complicate our antenna setup. We typically have run two
band fan dipoles.
Sent from my iPhone
> On Apr 14, 2015, at 2:38 PM, Rick - DJ0IP / NJ0IP <Rick@DJ0IP.de> wrote:
>
> 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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