[Elecraft] Balun Sugestions

[Jim Allen]

Thanks, Bob.

I have scoured Rick's website for some time, on this and other topics, and corresponded with him extensively about various ideas.  I've also read dozens of web pages about baluns, any number of threads at QRZ.com on the topic as well.  There are confusing, contradictory and often mutually exclusive points of view and no clear direction how to go for those of us whose understanding of these things is fairly shallow.  Each approach has disadvantages, detractors and claimed limitations, it seems.

I could easily make a balun with a ferrite toroid core, as shown by G3TXQ with 10-12 turns of some RG8x, which I have in hand, pop it in a box with a couple of connectors, and have a go with that.  I am sensitive to losses, since with QRP and modest antennas due to external limitations, I have no dbs to waste.  I need to have one, or two, good multi band antennas.  I try to avoid store bought antennas, and anything with radials are a no-go here on the Rock Ranch..

I just started using the KAT100.  Pretty slick.  With a good quality balun, it has some attractive features, replacing the AH-4.  I have also been tempted by the MFJ974HB balanced tuner.  No balun needed but no KAT100 needed either.  I wish I could find the parts to roll my own!

I have been using balanced feed lines for the various antennas since I moved here ~30 months ago with gratifying results.

Keep the suggestions coming!

73 de W6OGC Jim Allen 
Message: 23
Date: Thu, 4 Feb 2016 17:10:39 -0600
From: Bob McGraw K4TAX <rmcgraw at blomand.net>
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Balun suggestions
Message-ID: <56B3DA6F.3090208 at blomand.net>
Content-Type: text/plain; charset=windows-1252; format=flowed

As one that has personally used a balanced fed antennas for years, I 
suggest you review the info on this site.
 http://www.dj0ip.de/balun-stuff/ <http://www.dj0ip.de/balun-stuff/>

Good stuff on evaluating or building a proper balun.

And for open wire fed antennas:
http://www.dj0ip.de/open-wire-fed-ant/

To answer your question, a high power 1:1 current balun is likely best.  
Of course you could built a balanced tuner as I did.  Problem solved.  
That's another story.

Keep in mind that balun power ratings are for "matched" conditions. 
Which in fact is never the case with a center fed wire and open wire or 
a  balanced feed line.  At a mighty 5 watts it would not be of concern.

If at all possible, run the balanced feed line from the antenna feed 
point all the way to the operating position.  Keep the coax run between 
the tuner output and balun input as short as practical. After all, the 
reason to use balanced feed line is to take advantage of the low loss 
properties.

Never fear, the use of balanced feed line is not near as critical or 
fussy as the "masses" will so tout.  Many hams express fear in using 
balanced feed systems, largely because of what they have heard. Mostly 
because it frankly isn't fact.  Mine feeds a 256 ft center fed wire and 
comes down the tower supported on home made 9" PVC stand-offs, through 
the attic eve vent, across the roof rafters, and drops down through the 
ceiling to the tuner on the shelf above the desk.  Not bad for a 160M - 
10M antenna.    {see my pix on QRZ.COM that shows a bit of the line 
going up the wall.}

73
Bob, K4TAX

Sent from my iPad