Topband: Topband Digest, Vol 149, Issue 17

Sat May 30 12:17:04 EDT 2015

An UN-UN is un balanced to unbalanced. Is that what you have ? A vertical  
is unbalanced. Willy

In a message dated 5/30/2015 12:02:54 P.M. Eastern Daylight Time,  
topband-request at contesting.com writes:

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Today's Topics:

1. vertical  balun (Bob Kupps via Topband)
2. Re: vertical balun  (shristov)

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Message:  1
Date: Fri, 29 May 2015 21:13:50 -0700
From: Bob Kupps via Topband  <topband at contesting.com>
To: topband  <topband at contesting.com>
Subject: Topband: vertical  balun
Message-ID:
<1432959230.96755.YahooMailBasic at web125001.mail.ne1.yahoo.com>
Content-Type:  text/plain; charset=us-ascii

Hi we have a 30m top loaded monopole with  the feed point about 2m above a 
large ground radial field. Right now we are  feeding it through a 4:1 balun 
(not a unun) with 12.5 ohms on the balanced  side, and the SWR is 1.4 with 
no matching network. Is this balun acting as a  common mode choke? Do we even 
need a choke? Would an unun be  better?

Thanks 73 Bob  HS0ZIA

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Message: 2
Date:  Sat, 30 May 2015 06:40:14 +0200
From: shristov  <shristov at ptt.rs>
To: topband  <topband at contesting.com>
Subject: Re: Topband: vertical  balun
Message-ID: <fb2e9fb35082.55695b4e at ptt.rs>
Content-Type:  text/plain; charset=us-ascii

Bob Kupps wrote:

> Right now we  are feeding it through a 4:1 balun (not a unun) with 12.5 
ohms on the 
>  balanced side, and the SWR is 1.4 with no matching network.

You  should get quite a reasonable SWR with no matching at all.
A good  high-impedance common mode choke is  recommended.

73,

Sinisa  YT1NT,  VE3EA

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End  of Topband Digest, Vol 149, Issue  17
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