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Re: [TowerTalk] Mounting 1.25 stinger in 3" tubing?

To: TowerTalk@contesting.com, terry burge <ki7m@comcast.net>
Subject: Re: [TowerTalk] Mounting 1.25 stinger in 3" tubing?
From: terry burge <ki7m@comcast.net>
Reply-to: terry burge <ki7m@comcast.net>
Date: Sat, 8 Jun 2019 23:23:31 -0700 (PDT)
List-post: <mailto:towertalk@contesting.com>
Jeff,

I found when building my 40 meter 4-square weight was a big problem when 
raising and lowering 32-34' verticals. I bought my tubing from DXEngineering, 
mostly 0.120" thick wall aluminum. But the top 15' or so I used 2" irrigation 
tubing. That helped when raising and lowering for doing the needed adjustments. 
A lot of adjustments to get the dump power down. Going from 3" X 0.120" X 144" 
to 2" irrigation tubing took progressively smaller diameter sections. A lot of 
6' pieces of course. I used between 1' overlap down to 5" or so as I recall 
except for maybe the 2" irrigation top piece. Made sure I could have enough to 
adjust the resonance to where I needed it. Turned out some VERY strong, well 
build verticals as you can see on my www.qrz.com/KI7M page and used Comtek 
4-square setup. Works pretty well but 4-squares are a different breed of animal 
to tune up. You sort of forget about the SWR and go by dump power. Awhile back 
I got 3-4 S-units front to back which definitely made me happy. 

Hope this helps you in your plans.

Terry
KI7M

> On June 8, 2019 at 12:44 PM Mpridesti via TowerTalk 
> <towertalk@contesting.com> wrote:
> 
> 
> Jeff
> 
> Should be no issue using dramatically different diameters and I believe 
> modeling programs will give the additional length required for resonance. 
> 
> Anytime you have a step in diameter, you have lengthen the overall element to 
> compensate. 
> 
> Just guessing, you probably need 2 or 3 ft more of element length to offset 
> the 3 inch to 1.25 inch transition. 
> 
> Others here can be more precise. 
> 
> Regards,
> 
> Mark, K1RX
> 
> 
> > On Jun 8, 2019, at 12:08 PM, Jeff Blaine <KeepWalking188@ac0c.com> wrote:
> > 
> > I'm rebuilding my 40m 4-sq verts and have some 15' lengths of 3" OD/ 2.75 
> > ID tubing to use on the base end.  And for the "stinger" end, I have some 
> > tapered elements off an old yagi that are 1.25" OD on the bottom of the 17' 
> > length.
> > 
> > Other than buying some concentric lengths of aluminum to step from the 1.25 
> > OD stinger up to the 2.75 ID base tubing, any good ideas of an interposer 
> > that would take up some of the space?
> > 
> > 73/jeff/ac0c
> > alpha-charlie-zero-charlie
> > www.ac0c.com
> > 
> > _______________________________________________
> > 
> > 
> > 
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