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Re: [TowerTalk] Inverted vee mounted above HF Yagi

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Inverted vee mounted above HF Yagi
From: K8RI on TT <k8ri-on-towertalk@tm.net>
Date: Wed, 17 Aug 2011 18:15:51 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 8/17/2011 3:47 PM, Eddy Swynar wrote:
> Hi Jack,
>
> Some 30+ years ago VE3CSZ mounted a half wave dipole / inverted "V" atop his 
> Hy-Gain multi-element rotatable yagi on a 64' tall tower---I thought it was 
> ingenious at the time...
>
> Zenon had the pipe that the yagi was bolted to EXTENDED UPWARDS well past the 
> yagi itself: he then---somehow!---affixed a bearing atop this extension,&  
> the dipole to the bearing. Result: as the beam itself was turned, the dipole 
> / "V" itself was stationary, being affixed as it was to the outside of the 
> bearing assembly!
>
> He had the extension up high enough so that the dipole would clear the outer 
> elements of the yagi as it was steered.
>
> But how he concocted the thing to the bearing is lost upon me, being strictly 
> a "wire up in the trees" antenna aficiando such as I was at the time...
>
> Rest assured, it CAN be done---and VE3CSZ did it way back when!
>
> ~73~ de Eddy VE3CUI - VE3XZ
>
>
> ************************************************************************************************************************
>
>
> On 2011-08-17, at 3:31 PM, Jack White wrote:
>
>> 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.

The Yaesu thrust bearings even come with small brackets as would be used 
to guy a rotating pole. They can easily turn a steel mast into a 
rotating pole.  The same arrangement could be used to support the ends 
of an inverted V at the feed point. This does come with some risk, 
particularly if you live in an area where freezing temps are common or 
worse yet, ice storms.  If that bearing sticks "for any reason" it is 
likely to wind up and break the inverted V leaving a real mess of wire 
wrapped around the other antennas "up top". Hence the wire would need to 
be strong.   This is neglecting what side effects this antenna will have 
on the tri bander or other antennas under it. Unlike a 40m beam or 
dipole mounted above the tribander it will end up pointed right at the 
antenna at close range.

73

Roger (K8RI)
>>
>>
>>
>> 73, Jack G8DX
>>
>>
>>                                      
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