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Re: Topband: Wire closeness in two wire Beverage

To: <topband@contesting.com>,"Hermod Pedersen" <hermod.pedersen@bolina.hsb.se>
Subject: Re: Topband: Wire closeness in two wire Beverage
From: "Ford Peterson" <ford@cmgate.com>
Date: Tue, 24 Aug 2004 20:04:32 -0500
List-post: <mailto:topband@contesting.com>
Hermod wrote:

> Having at last found time to study the recent, and most interesting, "Two 
> Wire Beverage thread" I cannot find the answer to one particularly 
> interesting question:
> How close should one put the wires in a two wire Beverage system?
> 
> I would be most happy if anyone could pass on the answer to that particular 
> part of the discussion.

While I can hardly be considered an expert, having successfully constructed all 
of ONE beverage, I think the qualified answer to your question is "YES."

Yes, you can make a beverage out of any of these wires, coax, 1" 1.5" 2" 8" 10" 
12" 24".  Pick one.  And then make it work.  The wider you go, the higher the 
line impedance.  The narrower you go, the more difficult it is to make the 
lines remain parallel over the length (wind being the primary problem).

I picked 10" because the impedances were still within 'windability' at 688 ohms 
and that the wires could be held in relative proximity along the line.  Some 
use ladder line to get the 450 ohm lines over 450 ohm surge impedance, which 
means one-to-one transformers at one end and 9 to one at the other (for 50 
ohm).  I personally hate the 'flat' lines as the wind really grabs them.  50MPH 
winds are not uncommon around here.  Any flat strapping material will vibrate 
like a guitar string in the wind.  Round profiles will not do this.  

The 688 ohm would work pretty well with 75 ohm feeders (9:1).  And I don't 
think the wind will be able to take the slack in the lines and wrap them around 
one another.

Ford-N0FP
ford@cmgate.com


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