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Re: [TowerTalk] Balun Recommendation

To: Steve Hunt <>
Subject: Re: [TowerTalk] Balun Recommendation
From: Frank <>
Date: Sat, 21 Apr 2012 09:47:23 -0500
List-post: <">>
Steve Hunt wrote:

>If the coax in the shack sees a low impedance path to ground, and it is 
>an odd multiple of a quarter-wave up to the feedpoint, very little CM 
>current flows; and for any that does flow the shack end is at a voltage 
>*minimum* of the CM standing wave. It's very clear if you look at the 
>current distributions in a model.
>Of course, if the shack is on a second floor all bets are off - the coax 
>may well not see a low impedance path to ground.
>Steve G3TXQ

 From that information can I conclude that if I have a decent, short 
length ground connection and a feedline that is an odd multiple of 
quarter wavelengths long, I don't need a CM choke?

Consider as application a 2 meter quagi at 40 feet.

Also how about a longer ground that is a multiple quarter wavelengths 
long.  If that works for the feedline why wouldn't it work for the 
ground wire?

I would much rather not have to invest in a CM choke and then find out 
later that there was no real difference with or without the choke.  If I 
need special equipment to discern a difference, I will probably not want 
to fool with it. 

Unless I can hear a difference in the headphones, I have to conclude 
that there is no difference.  At least no difference that I would be 
willing to pay for or spend time on.

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