[TowerTalk] Vertical plans

[WA3GIN]

Another approach might be to use two 30ft sections of 3" irrigation tubing. 
We did this for a Field Day antenna.  Used a block of pressure treated 4X4 
that was turned on the ends to slip into the tubing. We left about a foot of 
wood between to two sections of tubing and mounted a  rotary coil on the 
wood coupling block to connect the two sections. Attached to the coil was a 
small DC motor. The wood was center bored  with a channel to one side so 
that the DC motor wire could be run into the block and down the lower 
section  of the tubing. The coil gave us the ability to span the entire 
75-80m band.  The surprise for us was that the old surplus coil had enough 
inductance to get the antenna to resonate on 160m.

Have Fun,
dave
wa3gin

----- Original Message ----- 
From: "Jim Hoge" <knowkode at sbcglobal.net>
To: "W5CPT" <w5cpt at bellsouth.net>; <towertalk at contesting.com>
Sent: Sunday, April 06, 2008 10:46 AM
Subject: Re: [TowerTalk] Vertical plans


> Clint,
>
>  Why settle for a loaded vertical if you are in the country? You are only 
> talking another ~20' of height for a full sized 1/4 wave antenna. If you 
> do proceed with this design, consider doubling up the tubing at the top of 
> the vertical where it is drilled for the tophat. Also consider something 
> more electrically and mechanically sound than just putting hose clamps on 
> the tophat elements to hold them in place. Over time, wind induced 
> vibrations may widen the holes through which the tophat passes, leading to 
> failure either mechanically or electrically- in this case giving you an 
> intermittantly non resonant antenna. As for base loading with a coil, 
> consider multiple taps switched in and out to give you the bandwidth you 
> desire.
>
>  Jim W5QM
>
>
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