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Re: [TowerTalk] Ferrite Balun on a LPDA decision

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Subject: Re: [TowerTalk] Ferrite Balun on a LPDA decision
From: "Clint Talmadge" <>
Date: Fri, 15 Jun 2007 09:27:45 -0500
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Hello all and thank you for all the replies both on and off reflector. I have 
made a decision on the Balun.

I will use the Unadilla W2DU  (sorry about confusing the AU in the original 
post though no one commented on the use of a Voltage Balun vs. a Current Balun) 
at the feed point (front) of the LPDA.

While Tom W8JI raises some valid points about the location of the balun, 
Tennadyne instructions are to put the recommended balun at the feed point. This 
would have the same effect regardless of what type balun is used. I am using a 
Current Balun and the lower boom, to which the balun is secured is attached to 
the shield of the coax. The only way I see to make sure that none of the 
induced currents are carried by the coax down the tower is to install an inline 
common mode choke at the point where the coax makes the turn off the boom to 
the mast. I am still considering that and if there were a Ham Radio store close 
to me I would do it just to be sure (sort of like a belt and suspenders).

Dan's article on baluns was very insightful but the numbers achieved for the 
ferrite balun do not correlate with those on the Unadilla web site. Of course 
Unadilla is in the business of selling these things and Dan is not so the 
disparity is somewhat understandable. None the less I will use the W2DU for all 
the other reasons stated in the original post and "suffer" through with the 
performance of the ferrite.

I have a good data set as how the antenna played with the coax balun and will 
compare it to the ferrite once up. I will report back on what I find.  I have a 
strong feeling that there will be an improvement but I will not be able to 
attribute it to just the balun given the progress of the cycle and new antenna 
height. It may take a while to get the tower up as the bride has serious 
misgivings about my climbing towers since my bypass surgery.

Clint - W5CPT


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