Hi Brian,
It depends on what you call a benefit. For us there was a HUGE
benefit in being able to locate a full sized halfwave vertical
radiator at a particular point fairly high in the air and feed it
with only 50 feet of Coax to our TX on the ground.
Without the J-pole feed method, we were looking at 500 feet or so
of RG214 with its attendant cost and weight problems to get it in
place. As it was, we made the 1/4 wave open wire stub for about
$50 and were able to use it as a convenient support for one end
of the radiator. We didn't think we could have easily or cheaply
maintained the radiator in the right place with RG214 and a balun
hanging at the center of the radiator wire even if we did want to
fork the bucks for the 500+ feet of cable.
The J-pole feed system permitted us to build a very effective
full sized 160 meter vertically (mostly) polarized antenna which
could be raised and lowered by a single person for testing and
tuneup. Pull it up with one rope, let it down with one rope.
Although this wasn't really one of our initial goals, it became
clear during the project that this was a tremendous benefit for
us.
We didn't do all that bad in the contest with it either. Would
have done better if we had gotten the beverages in place for RX.
If you look up our score, bear in mind that we were receiving on
the TX antenna...
73, Eric N7CL
To: <towertalk@contesting.com>
>Date: Thu, 31 Dec 1998 16:37:20 +0000
>From: alsopb <alsopb@gloryroad.net>
>
>I guess I'm missing something. Is there any benefit of any kind
>(especially on the HF bands) to using a J-pole? It strikes me
>it is an intellectual persuit without any real world benefits.
>
>de Brian/K3KO
>
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|