[TowerTalk] And one more thing.....

[Steve, W3AHL]

The two common solutions to grounding the Tennadyne LPDA elements and boom 
is to:

1.  Use a shorting stub at the rear of the boom, which helps tune out some 
anomalies also.
2.  Use a Collins choke (coiled coax) at the feed point.
3.  Bond the feed line shield to the top and bottom of the tower.

This does not work of course if an isolating choke is used at the feed 
point, in which case:

1. Connect an RF choke as Gene suggested or  Polyphaser from each split-boom 
to the mast or tower.

Steve, W3AHL

----- Original Message ----- 
From: "Gene Smar" <ersmar at verizon.net>
To: "Tower and HF antenna construction topics." <towertalk at contesting.com>
Sent: Monday, January 25, 2010 12:35 PM
Subject: [TowerTalk] And one more thing.....


> Gents:
>
>     I neglected to comment in my previous post about a significant issue 
> with LPs.  The boom halves as well as the elements are all above RF 
> ground.  Scroll down a bit on http://www.tennadyne.com/assembly.htm and 
> you'll see a boom-to-mast insulator.  Essentially, the boom halves serve 
> as an open-wire transmission line from the coax/balun back to the last 
> elements pairs.  It is essential that you keep this in mind when planning 
> your stations.  Those who are in lightning-prone areas may wish to shunt 
> the boom halves to the mast with suitable RF chokes, perhaps at the 
> boom-to-mast plate, much as some have done with their Yagi DEs when using 
> them as top-loading for low band operation.
>
> 73 de
> Gene Smar  AD3F