[Towertalk] Ground the coax braid on LPDA or not?

[EUGENE SMAR]

Lou:

     Just a guess on my part, but maybe you could consider using a reactive
component (inductor?) whose impedance is let's say ten times the coax feed
(500 Ohms) at the lowest freq of the LP.  Many folks suggested that approach
when I was considering shorting the elements of my Bencher Skyhawk Yagi to
the boom for capacitive loading on my tower.  For me that was too much
trouble, so I simply shorted the parasitics to the boom with small pieces of
aluminum flashing, self-tapping screws (through the elements) and a hose
clamp for the boom end of the flashing.  But I believe you'll have no choice
but to use an inductor of some design.

73 de
Gene Smar  AD3F
-----Original Message-----
From: Louis Sica, Jr. <lsica@attbi.com>
To: towertalk@contesting.com <towertalk@contesting.com>
Date: Monday, December 09, 2002 3:40 PM
Subject: [Towertalk] Ground the coax braid on LPDA or not?


>I have a T8 8 element LPDA on top of a 50 foot tower. That same tower also
>has a DX-A half sloper on it. The problem is that since the LPDA boom is
>electrically isolated from the tower, I don't get the advantage of the top
>loading that antenna would bring, and that makes the performance of the
DX-A
>sloper not where it could be.
>
>My question is, can I electrically connect the LPDA to the tower by
>grounding the braid of the coax to the tower? I've heard conflicting
reports
>on this. Some say I'd wind up reducing the performance of the LPDA
>noticeably, some not. Even those who recommend the connection disagree on
>where to do it. Some say it would have to be done near the top of the tower
>to take advantage of the top loading of the LPDA, some a ground the bottom
>would be just as effective and wouldn't cause the performance degradation
in
>the LPDA.
>
>Expertise and even educated opinions are appreciated
>
>
>73
>Lou AC0X
>
>_______________________________________________
>AN Wireless Self Supporting Towers at discounted prices,
>See http://www.mscomputer.com
>
>Wireless Weather Stations now $349.95. Call Toll Free,
>888-333-9041 for additional information.
>_______________________________________________
>Towertalk mailing list
>Towertalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk