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:[email protected]] On Behalf Of Mike Waters Sent: Friday, November 6, 2015 5:21 PM To: Bill Hider <[email protected]> Cc: topband <[email protected]> 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 <[email protected]> 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/ > _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
