An added observation is the preforms on boom guys can interact. I
notice this on my 10m 5 + 5 stack with swr a bit off.
These antennas previously used Nicopress sleeves on the Phillystran.
Recently, I discovered this is a termination method ok'd by Phillystran
up to 1/2", four copper sleeves per termination. Optionally, wrap with
#33, which adds UV protection for the Kevlar should any be exposed (I
don't see any exposure on previous gen boom guys). I also think the
Nicopress results are better than using cable clips as there is
immediate deformation of the plastic cover so the compressed sleeve
bears on the kevlar.
Grant KZ1W
On 10/3/2019 6:36 AM, john@kk9a.com wrote:
I am not sure how you know that the pattern was distorted but I think
this is a good practice Tim. My top homebrew 15m beam has a higher SWR
than the lower two - 1.4:1 vs 1.1:1.?? Just below the top antenna is a
Rohn 65 massive star guy bracket with six Phillystran Big Grips directly
attached.?? Perhaps insulating the guy would help.
John KK9A
Tim Duffy k3lr at k3lr.com
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.
73
Tim K3LR
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