[TowerTalk] Gamma-matched 4-square

[jeremy-ca]

And if you prefer elevated radials old tower sections that would not pass 
muster as a tower and aluminum sections split by ice make excellent 
supports.
There are several ways to fabricate insulators for this method.

At a prior QTH I shunt fed 100 and 120' towers, both with yagis on them. 
Spacing was 70' and they performed well with simple coax line phasing. F/B 
was only 10-15dB but I used Beverages for RX so didnt care about that. I 
moved a year later of course and had to start all over.

Carl
KM1H


----- Original Message ----- 
From: "Scott W3TX" <superberthaguy at adelphia.net>
To: "Roger (K8RI)" <K8RI-on-TowerTalk at tm.net>; "joe johnson" 
<joe.k3rr at gmail.com>; <towertalk at contesting.com>; "Jim Lux" 
<jimlux at earthlink.net>
Sent: Thursday, July 05, 2007 9:56 AM
Subject: Re: [TowerTalk] Gamma-matched 4-square


> John ON4UN addresses this question in "Low Band DXing".
>
> His advice was to avoid shunt fed elements in a driven vertical array.
>
> If the elements are dedicated  (ie. not a shunt fed tower) then it is 
> really
> very easy to end feed the elements (insulated from ground):
>
> Use a 6" piece of Garolite, or other suitable FRP rod, machined to 
> telescope
> into the bottom section of aluminum tubing.  Pour a small concrete pad
> (perhaps 1ft cubed) base for each vertical element and during the concrete
> "set" impress the FRP rod 2" deep into the center of the pad.  A few days
> later sleeve the FRP rod 2" into the bottom aluminum section and cross 
> bolt
> it in place.  Thus there is a 2" gap between the element bottom and the
> cement pad. One of the bolts can be used as a simple connector for the 
> coax
> center conductor. Place three ground rods around the circumference of the
> concrete pad. Cadweld a circular piece of plumber's copper tubing to each
> ground rod. Connect your feedline ground to one of the rods. Connect your
> radials (60 to 120 recommended) to the copper circle. Now you have a 
> simple
> and cost effective base insulated element.  If you ever take it down just
> pull the FRP out of it's indentation in the concrete and the FRP goes with
> you!
>
> 73, Scott W3TX
>
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