[TowerTalk] BALUN QUESTION

[ersmar@comcast.net]

Robert:

     I homebrewed a balun for my 3L Yagi.  I'm not sure how to tell if it's doing any good, but I installed one 'cuz the manufacturer said I ought to.

     Unlike you I wound mine as a separate unit, with PL-259 at the feed end and terminals at the antenna end.  I connected it to the main coax through a barrel connector (PL-258, I think) and lots of tape.

     Mine is made from RG-213 and consists of five turns wound around a small paint can about four and a half inches in diameter.  I determined the number of turns by winding eight or so turns around the form and connecting the coax shield to my MFJ259 analyzer.  Note:  I ignored the center conductor for this measurement and connected the coax shield as if it were a large-diameter conductor.  I then measured the impedance of the solenoid balun as I ran the MFJ through the HF range.  I took off turns until I got somewhere around 250 Ohms (5 X 50 Ohms of the coax) of inductive reactance across the HF range.  I held the solenoid coil in place with tape and used quite a few large plastic wire wraps and tape to help the coax hold this shape when I removed the can.  

     The PL-259 at the feed end is easy.  Sealing the antenna end from the weather is a bit trickier.  I posted this: http://lists.contesting.com/archives//html/Towertalk/2002-10/msg00391.html on TowerTalk after I had installed my own balun.  Hopefully it will help you, too.  


73 de
Gene Smar  AD3F


> hi,
> i am getting ready to install a h/brew  2 el 12m yagi. i  scrounged the 
> reflector & split driven ele. off an old Mosley. I am thinking  of h/brewing a 
> balun. Arrl handbook gives apx size on a coiled up one. i am  thinking more 
> along 
> the line of wrapping one arnd. 2'',3'' or 4'' pvc. anyone  rolled ur own out 
> there? was also considering making this 'in line'. Just  rolling it at the end 
> of the coax feed line with no breaks or connectors before  the feed piont. i 
> might just skip the balum altogether. i've used split d/ele  feeds with and 
> without and i tend to think the balun helps. i'm interested if  any readers have 
> made their own baluns and the result.the antenna is from an  article by Cebik. 
> it has a 6' boom  to help make the impedence closer  to 50 ohms. 
> k9il
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