Consider using a linear loading arrangement at the bottom of each vertical.
This is what I did on my 4 square that I had in CA and it worked really
well. All 4 of my antennas were made from 3" irrigation tubing with the
bases at 8 feet off the ground. I ran a length of AWG10 from the bottom, up
4 feet, across but not touching the tubing, and back down to the starting
point and connected to a insulator. I then used a slider to adjust the
linear loading section. My verticals came out to be 63' tall and I had them
resonant at 3800. I did use Dacron rope at 2 levels going in 3 directions
but if I put up another 4 square with 3" irr. tubing I will only guy them at
the 35 foot level because I removed the top guys about 6 months before I
actually took the array down and I had no problems, even with some strong
Santa Ana winds. That tubing is strong stuff.
Bob W6TR
----- Original Message -----
From: <donovanf@starpower.net>
To: <TOWERTALK@contesting.com>
Sent: Sunday, December 17, 2006 10:16 AM
Subject: Re: [TowerTalk] 80m 4-square materials
> Trent,
>
> Elegant simplicity is the reason insulated base verticals are the "defacto
> standard" for 4-square arrays. Each element is identical and most
> importantly there are no reactive elements between the transmission lines
> and the verticals. This makes it practical to design a relatively simple
> matching and switching network for the entire array.
>
> There are at least three big problems with adding a matching network at
> the base of each vertical:
>
> 1. only two of the verticals (the two that are fed in phase) have
> identical impedances. The leading and lagging phased verticals have
> significantly different impedances.
>
> 2. vertical base matching networks (e.g., a gamma match) change the RF
> current and phase delay to each vertical. Their affect will not be
> identical as the array is switched because the impedance of each vertical
> changes when we switch direction.
>
> 3. wbecause we switch our 4-square verticals in four different directions,
> it is very different from AM broadcast arrays that are usually aligned for
> a single pattern. Because of (1) and (2), a 4-square array with matching
> at the base of each vertical (e.g., a gamma match) would require switching
> of three different networks at each vertical base.
>
> In summary: find a way to insulate the bases of your verticals. It will
> save you a huge amount of time and money (and maybe a masters degree in
> electrical engineering and several years of field experience with
> adjustment AM broadcasting arrays) if you try to use a gamma match on each
> vertical!
>
> 73!
> Frank
> W3LPL
>
> ---- Original message ----
>>Date: Sun, 17 Dec 2006 14:54:12 +1000
>>From: "Trent and Lorraine" <vk4ti@sampson.net.au>
>>Subject: Re: [TowerTalk] 80m 4-square materials
>>To: <TOWERTALK@contesting.com>
>>
>>
>>Greetings all, Could anyone enlighten me ? : Is there any practical reason
>>that free standing towers utilised in a gamma match configuration are not
>>used for 4 squares ? Locally there are heaps of old free standing tv
>>towers
>>that are around the 50 ft mark
>>
>>Trent VK4TI
>>
>>Trent Sampson
>>[PO Box 1647 Toowoomba Qld 4350] VK4TI
>>
>>
>>-----Original Message-----
>>From: towertalk-bounces@contesting.com
>>[mailto:towertalk-bounces@contesting.com] On Behalf Of john@kk9a.com
>>Sent: Sunday, 17 December 2006 12:15 PM
>>To: TOWERTALK@contesting.com
>>Cc: David Robbins K1TTT; mike@mallardcove.com
>>Subject: Re: [TowerTalk] 80m 4-square materials
>>
>>I don't know that Array Solutions still carries the 80m vertical.
>>ZeroFive
>>Antennas http://www.zerofive-antennas.com sells one that looks very
>>similar to the Array Solutions freestanding vertical for $2200. I built a
>>54' freestanding vertical at P40A for considerably less. For K1TTT's
>>installation, I would consider using 3" diameter aluminum tubing guyed at
>>two levels. The larger top sections will improve the bandwidth and I
>>think
>>it's a strong antenna than can be built for a reasonable price. I believe
>>that K4JA built his 80m 9 circle vertical array this way.
>>
>>John KK9A
>>
>>
>>To: <k1ttt
>>Subject: Re: [TowerTalk] 80m 4-square materials
>>From: "Mike Fatchett"
>>Date: Sat, 16 Dec 2006 09:16:16 -0700
>>List-post: <mailto:towertalk@contesting.com>
>>
>>I believe that Array Solutions also has full sized 80m verticals.
>>
>>
>>David Robbins K1TTT pravi:
>>
>>>I am trying to decide what to use to build 4 new 80m verticals for a
>>>4-square upgrade here. My criteria are:
>>>1. full size 1/4 wave verticals, no top or base loading.
>>>2. must be able to standup to new England winters at 2000' with ice and
>>>wind 3. must be new material, I don't want to go scrounging for used
>>>tower or pipe.
>>>4. prefer only 1 guy level, but will do 2 if necessary.
>>>5. prefer to stand up complete, but will climb to add top section(s) if
>>>necessary, crane or truck access will be very hard to this spot.
>>>6. prefer something that can be delivered to here, truck delivery is
>>>not a problem, I don't want to have to haul long stuff myself.
>>>
>>>So, what might fit those criteria??
>>>
>>>
>>>David Robbins K1TTT
>>>e-mail: mailto:k1ttt@arrl.net
>>>web: http://www.k1ttt.net
>>>AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>>>
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