An alternative to Bill's "stacked" wires is to use a single wire, with
feedlines to both ends, and a SPDT relay at each end to either connect the
Beverage wire to the feedline transformer or to ground it through a
terminating resistor. The relay voltage may be piggy-backed on the feedline,
with appropriate capacitor and resistor at each end to isolate the DC from
RF. Switching to one or the other feedline in the shack then switches
directions.
I used that system on several wires in the '80s and '90s and it worked well.
K1VR also wrote about a variation without the relays, bringing both
feedlines to the shack and switching there, with the unused one terminated
through a 72-ohm resistor (he was using 72-ohm feedline).
73/Jon AA1K
Felton, Delaware
www.aa1k.us
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Mike
Waters
Sent: Friday, November 6, 2015 5:21 PM
To: Bill Hider <n3rr@erols.com>
Cc: topband <topband@contesting.com>
Subject: Re: Topband: beverage layout
Hi Bill,
I see you have a wide vertical spacing (
http://users.erols.com/n3rr/photos/dual_ew-1.jpg).
I don't doubt that they work well, as you say.
I did a fair amount of analysis about that design in the past. I forget the
finer details, and I'm not in the mood for any more math and modeling today,
but I want to throw out an idea.
That design might work slightly better if the spacing wasn't as large, or if
the wires were side-by-side. The way it is, the ground underneath it
unbalances it somewhat. The Z of the upper wire to ground vs. the Z of the
lower wire to ground is unequal.
Exactly how much difference in F/B in the reverse direction that makes, I
don't remember. But in some situations, changing the spacing or turning the
wires 90 degrees might make the difference pulling a weak one out of the
noise and QRM.
Not picking on you. Just food for thought. :-)
73, Mike
www.w0btu.com
On Fri, Nov 6, 2015 at 1:07 PM, Bill Hider <n3rr@erols.com> wrote:
> My Website has detail ... on my two 275' Beverages (E & W) mounted on
> a single set of posts. ... I've been using all these since 2000. ...
> Scroll down to the System Design links & click on "Beverages".
>
> Here:
> http://users.erols.com/n3rr/
>
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