[TowerTalk] Ferrite Balun on a LPDA?

[n7ka at comcast.net]

Guess I need a bit of clarification on a point or two.  I am thinking monoband yagi, not LPDA  for my questions.

1.  You state
     "the  coax needs to be routed down the boom tied to the shield."

I take this to mean the shield of the coax should be connected to the boom close to the feed point.  

2. You state
    "If you tape the coax to the boom  the balun needs to be at the point where the coax leaves the boom to go to the tower, not out at the feedpoint" 

I take this to mean placing rhe balun after the 90 degree turn from the horizontal boom to the vertical mast.  Will taping the balun and coax down the mast have detrimental affects?  Will the balun need to be spaced from the mast and if so how far?

In the case of an OWA type antenna with split dipole feed(dipole insulated from the boom), would the coax shield get grounded to the boom near the feed point and the balun placed after turning down the mast?

Arne N7KA


-------------- Original message -------------- 
From: "Tom Rauch" <w8ji at contesting.com> 

> >I am close to putting my Tennadyne T-6 back up. When I took 
> >it down it had the prescribed Coax Balun on it and it 
> >showed it's age. For the last month or so I have had the 
> >antenna on a short perch in the yard with a Ferrite Bead 
> >Balun on it and it sweeps fine using an analyzer and I have 
> >even made a few DX contacts on it. The balun I am using is 
> >a W2AU by Unadilla. I have searched different archives and 
> >the only one with any significant information is one I 
> >started on eHam some years ago.The old Tennadyne maker 
> >specifically said he had not tested a ferrite balun and did 
> >not recommend them. The reasons I would like to use the 
> >Ferrite Balun are: 
> 
> >>> 
> 
> 
> Watch how you run the coax. If you use a balun and then tape 
> the coax to the boom (which is hot) you totally defeat the 
> reason for having a balun. If you tape the coax to the boom 
> the balun needs to be at the point where the coax leaves the 
> boom to go to the tower, not out at the feedpoint, and the 
> coax needs to be routed down the boom tied to the shield. 
> 
> 73 Tom 
> 
> 
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