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Re: [TowerTalk] Inverted vee mounted above HF Yagi

To: "Jack White" <>, <>
Subject: Re: [TowerTalk] Inverted vee mounted above HF Yagi
From: "Chuck Lewis" <>
Date: Wed, 17 Aug 2011 16:07:30 -0500
List-post: <">>
Jack, for the past 10-12 years, our club has used a simple device for our 80M 
vee over a 20M quad for Field Day. We found a sealed automotive bearing whose 
O.D. was just right for slipping into the mast we use to hold the Vee above the 
quad (you'll have to do the math to figure out how high it needs to be to clear 
the A3WS). Slot the mast so the bearing can be FIRMLY clamped into the mast at 
the top. Find a 1/4-20 galvanized eyebolt about 10" long, and bend the threaded 
end, with heat, at 90 degrees to the 'eye-end'. Bend just enough of the 
threaded part to be passed through the I.D. of the bearing and be clamped in 
place by washers with nuts on top & bottom. We used the washers that are found 
at the top of automotive front shock absorber mounts (the ones that squeeze the 
rubber mounting washers). The nice thing about these washers (the metal ones) 
is that they are dished a bit and will self-center in or around the bearing 
I.D. while clearing the outer race. With the bent end
  in place in the center of the bearing, clamp the bearing O.D. in the mast 
using a S.S. hose clamp. Now you have a pivoting hanger that's offset from the 
mast by the unbent length of the eyebolt. It might be a good idea to use some 
cold galvanizing at the spot that was heated. 

When you choose the anchor points for the inverted vee ends, make sure they are 
not directly in line with the mast. There needs to be a little side-load on the 
eyebolt to keep it always on one side as the mast rotates under it. You'll have 
to adjust the antenna tension by watching the position of the pivot; pull one 
end or the other until the pivot is straight out from the mast and roughly 90 
degrees to the plane of the vee. A loose wrap or two of coax around the mast 
will be sufficient. We use two 10' sections of cheap TV mast, but that's a 
Field Day approach and, besides, you might need more height to clear the yagi. 
We've always wondered about whether the threaded part in the bearing would 
remain lined up with the mast axis, but it has survived a LOT of Southern 
Summer thunderstorms and is still perfect. One weekend per year doesn't amount 
to a definitive test, even after quite a few years; but there's no evidence of 
degradation so far. I wouldn't hesitate to use it for a 
 permanent installation, but your mileage may vary!  

Good Luck!

Chuck, N4NM

  ----- Original Message ----- 
  From: Jack White 
  Sent: Wednesday, August 17, 2011 2:31 PM
  Subject: [TowerTalk] Inverted vee mounted above HF Yagi

  Hi Guys

  I have a standard 60ft Versatower with a Yaesu G-1000 and bearing mounted at 
the top, and just above this I have a Cushcraft A3WS (pic on QRZ). I want to 
extend the stub mast about 20ft above the A3WS to support the centre of a 
160/80/40 trapped inverted vee. I'm looking for some type of mount that will 
allow me to mount the centre of the inverted vee at the top of the stub mast 
and remain fixed whilst the stub mast rotates. Ideas/advice would be great.

  73, Jack G8DX


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