The problem with Preform connections is much worse as you go higher in
frequency.
I only had a photo of the 40 meter install.
Knowing what I know now I would never direct connect a Preform to the tower.
73
Tim K3LR
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Steve
Maki
Sent: Wednesday, October 2, 2019 9:20 PM
To: towertalk
Subject: Re: [TowerTalk] EHS leads for Phillystran
It *disconnects* the preforms from the tower legs.
I must say I'm surprised that this action was needed when talking about
40 meters, but if one wants perfection, and sees SWR changes with
antenna rotation, then it's needed, no doubt about it.
-Steve K8LX
On 10/02/19 20:42 PM, Keith Dutson wrote:
> So this arrangement moves the preform away from the tower leg? I am
> rebuilding my tower and have three TIC rings mounted about 4 feet above
the
> guy mounts.
> I had a problem with just Preforms attaching to the tower legs connection
-
> which caused distortion in the pattern of close mounted Yagi's. That is,
> Yagi's that were mounted only a few feet above a guy connection point. The
> VSWR of the affected Yagi would change with rotation and the effect of
three
> Preforms connected to the tower was confirmed with modeling. The solution
> was to use a bent pin shackle and an insulator right at the tower
> connection. You can see it in this view of the middle four element 40
meter
> OWA Yagi stack at K3LR:
> http://www.k3lr.com/2016/ring.jpg
>
> Using insulators at the tower connection completely solved the pattern
> distortion and VSWR changes with rotation.
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